Co-reporter:Teppei Shirakura, Christof Smith, Thomas John James Hopkins, Yong-Eun Koo Lee, Filippos Lazaridis, Panos Argyrakis, and Raoul Kopelman
ACS Omega July 2017? Volume 2(Issue 7) pp:3380-3380
Publication Date(Web):July 10, 2017
DOI:10.1021/acsomega.7b00590
The use of a nanoparticle (NP)-based antitumor drug carrier has been an emerging strategy for selectively delivering the drugs to the tumor area and, thus, reducing the side effects that are associated with a high systemic dose of antitumor drugs. Precise control of drug loading and release is critical so as to maximize the therapeutic index of the NPs. Here, we propose a simple method of synthesizing NPs with tunable drug release while maintaining their loading ability, by varying the polymer matrix density of amine- or carboxyl-functionalized hydrogel NPs. We find that the NPs with a loose matrix released more cisplatin, with up to a 33 times faster rate. Also, carboxyl-functionalized NPs loaded more cisplatin and released it at a faster rate than amine-functionalized NPs. We performed detailed Monte Carlo computer simulations that elucidate the relation between the matrix density and drug release kinetics. We found good agreement between the simulation model and the experimental results for drug release as a function of time. Also, we compared the cellular uptake between amine-functionalized NPs and carboxyl-functionalized NPs, as a higher cellular uptake of NPs leads to improved cisplatin delivery. The amine-functionalized NPs can deliver 3.5 times more cisplatin into cells than the carboxyl-functionalized NPs. The cytotoxic efficacy of both the amine-functionalized NPs and the carboxyl-functionalized NPs showed a strong correlation with the cisplatin release profile, and the latter showed a strong correlation with the NP matrix density.Topics: Dissolution; Mechanical properties; Pharmaceutical hydrogels; Pharmacology; Polyamides; Polyesters;
Co-reporter:Chang H. Lee, Jeff Folz, Wuliang Zhang, Janggun Jo, Joel W. Y. Tan, Xueding Wang, and Raoul Kopelman
Analytical Chemistry August 1, 2017 Volume 89(Issue 15) pp:7943-7943
Publication Date(Web):June 21, 2017
DOI:10.1021/acs.analchem.7b00930
Ion-selective optodes (ISOs), the optical analog of ion-selective electrodes, have played an increasingly important role in chemical and biochemical analysis. Here we extend this technique to ion-selective photoacoustic optodes (ISPAOs) that serve at the same time as fluorescence-based ISOs, and apply it specifically to potassium (K+). Notably, the potassium ion is one of the most abundant cations in biological systems, involved in numerous physiological and pathological processes. Furthermore, it has been recently reported that the presence of abnormal extracellular potassium concentrations in tumors suppresses the immune responses and thus suppresses immunotherapy. However, unfortunately, sensors capable of providing potassium images in vivo are still a future proposition. Here, we prepared an ion-selective potassium nanosensor (NS) aimed at in vivo photoacoustic (PA) chemical imaging of the extracellular environment, while being also capable of fluorescence based intracellular ion-selective imaging. This potassium nanosensor (K+ NS) modulates its optical properties (absorbance and fluorescence) according to the potassium concentration. The K+ NS is capable of measuring potassium, in the range of 1 mM to 100 mM, with high sensitivity and selectivity, by ISPAO based measurements. Also, a near infrared dye surface modified K+ NS allows fluorescence-based potassium sensing in the range of 20 mM to 1 M. The K+ NS serves thus as both PA and fluorescence based nanosensor, with response across the biologically relevant K+ concentrations, from the extracellular 5 mM typical values (through PA imaging) to the intracellular 150 mM typical values (through fluorescence imaging).
Co-reporter:Teppei Shirakura, Aniruddha Ray and Raoul Kopelman
RSC Advances 2016 vol. 6(Issue 53) pp:48016-48024
Publication Date(Web):09 May 2016
DOI:10.1039/C6RA02414A
The efficacy of drug-loaded nanoparticles (NPs) for cancer therapy is related to (1) the cellular uptake of the NPs, (2) the ability to control drug release, and (3) the ability to deliver drugs to the cytosol, while evading the endosomal compartments. Here we present a NP carrier of cisplatin, made of poly(acrylamide-co-N-(3-aminopropyl)methacrylamide) (PAA) and a branched polyethylenimine (PEI), a source of primary, secondary, as well as tertiary amine groups. We found that (1) the cellular uptake of the NPs was highly enhanced by the PEI incorporation. However, surprisingly, this is not due to significant changes to the NP surface charge (zeta potential). Also, the PEI-incorporation into the PAA NPs resulted in (2) an accelerated release kinetics, (3) an ability to destabilize the endosomal/lysosomal membrane, and (4) a marginal increase in drug loading. The combination of the 4 aforementioned effects seems to account for the observed significant increase in the cytotoxicity of these cisplatin-loaded PEI-incorporated NPs, when applied to the 9L glioma cell line.
Co-reporter:Chang H. Lee;Uma Mahesh R. Avula;Hyung Ki Yoon;Rafael J. Ramirez;Steven R. Ennis;Yoshio Takemoto;Fred Morady;Todd Herron;Kuljeet Kaur;Omer Berenfeld;Jérôme Kalifa
Science Translational Medicine 2015 Volume 7(Issue 311) pp:
Publication Date(Web):
DOI:10.1126/scitranslmed.aab3665
An injectable cardiomyocyte-targeted photosensitizer nanoparticle allows for specific in vivo arrhythmia ablation.
Co-reporter:Hyung Ki Yoon, Xia Lou, Yu-Chih Chen, Yong-Eun Koo Lee, Euisik Yoon, and Raoul Kopelman
Chemistry of Materials 2014 Volume 26(Issue 4) pp:1592
Publication Date(Web):December 10, 2013
DOI:10.1021/cm403505s
This work is aimed at engineering photosensitizer embedded nanoparticles (NPs) that produce optimal amount of reactive oxygen species (ROS) for photodynamic therapy (PDT). A revised synthetic approach, coupled with improved analytical tools, resulted in more efficient PDT. Specifically, methylene blue (MB) conjugated polyacrylamide nanoparticles (PAA NPs), with a polyethylene glycol dimethacrylate (PEGDMA, Mn 550) cross-linker, were synthesized so as to improve the efficacy of cancer PDT. The long cross-linker chain, PEGDMA, increases the distance between the conjugated MB molecules so as to avoid self-quenching of the excited states or species, and also enhances the oxygen permeability of the NP matrix, when compared to the previously used shorter cross-linker. The overall ROS production from the MB–PEGDMA PAA NPs was evaluated using the traditional way of monitoring the oxidation rate kinetics of anthracence-9,10-dipropionic acid (ADPA). We also applied singlet oxygen sensor green (SOSG) so as to selectively derive the singlet oxygen (1O2) production rate. This analysis enabled us to investigate the ROS composition mix based on varied MB loading. To effectively obtain the correlation between the ROS productivity and the cell killing efficacy, a microfluidic chip device was employed to provide homogeneous light illumination from an LED for rapid PDT efficacy tests, enabling simultaneous multiple measurements while using only small amounts of NPs sample. This provided multiplexed, comprehensive PDT efficacy assays, leading to the determination of a near optimal loading of MB in a PAA matrix for high PDT efficacy by measuring the light-dose-dependent cell killing effects of the various MB–PEGDMA PAA NPs using C6 glioma cancer cells.Keywords: methylene blue; microfluidic chip; photodynamic therapy; polyacrylamide nanoparticle; reactive oxygen species (ROS);
Co-reporter:Teppei Shirakura, Taylor J. Kelson, Aniruddha Ray, Antonina E. Malyarenko, and Raoul Kopelman
ACS Macro Letters 2014 Volume 3(Issue 7) pp:602
Publication Date(Web):June 12, 2014
DOI:10.1021/mz500231e
Improving the therapeutic efficacy and reducing systemic side effects of drugs is an important aspect in chemotherapy. The strategy presented here is the use of cisplatin loaded, temperature-sensitive, hydrogel nanoparticles (CisPt-NPs) and their ability to deliver and release chemodrugs selectively, based on thermal stimuli. The specially synthesized CisPt-NPs show a temperature-dependent increase of cisplatin release, at neutral pH (as in blood and normal tissue), in both the presence and absence of common metallic ions, as well as at the low pH found in lysosomes, where endocytosed NPs often localize. These CisPt-NPs were uptaken by breast cancer MDA-MB-435 cells, via endocytosis, and then mostly localized in the lysosomes. The in vitro cytotoxicity tests show that these CisPt-NPs have a significantly better efficacy at the slightly elevated temperatures. Potential applications are discussed.
Co-reporter:Ming Qin;Yong-Eun Koo Lee;Aniruddha Ray
Macromolecular Bioscience 2014 Volume 14( Issue 8) pp:1106-1115
Publication Date(Web):
DOI:10.1002/mabi.201400035
Abstract
The efficacy of chemotherapy is often inhibited by multidrug resistance (MDR). A highly engineerable hydrogel nanoparticle (NP) serves as a carrier for the optimal codelivery to tumor cells of the chemodrug, doxorubicin (Dox) and the chemosensitizer, verapamil (Vera), aiming at alleviating tumor MDR. The hydrogel NPs are prepared via the copolymerization of acrylamide and 2-carboxyethyl acrylate. Dox and Vera are post-loaded into the respective NPs, with drug loading around 7.7 wt% and 8.0 wt%, respectively. The codelivery of Dox-NPs and Vera-NPs increases the intracellular accumulation of Dox, and significantly enhances the cell killing ability of Dox with respect to NCI/ADR-RES cells in vitro. These findings suggest that such codelivery nanoplatforms provide a promising route for overcoming tumor MDR.
Co-reporter:Dr. Ariel Hecht;Patrick Commiskey;Filippos Lazaridis; Panos Argyrakis; Raoul Kopelman
ChemPhysChem 2014 Volume 15( Issue 16) pp:3444-3446
Publication Date(Web):
DOI:10.1002/cphc.201402048
Abstract
We use fractal analysis to calculate the protein concentration in a rotating magnetic assembly of microbeads of size 1 μm, which has optimized parameters of sedimentation, binding sites and magnetic volume. We utilize the original Forrest–Witten method, but due to the relatively small number of bead particles, which is of the order of 500, we use a large number of origins and also a large number of algorithm iterations. We find a value of the fractal dimension in the range 1.70–1.90, as a function of the thrombin concentration, which plays the role of binding the microbeads together. This is in good agreement with previous results from magnetorotation studies. The calculation of the fractal dimension using multiple points of reference can be used for any assembly with a relatively small number of particles.
Co-reporter:Ming Qin, Hong Zong, and Raoul Kopelman
Biomacromolecules 2014 Volume 15(Issue 10) pp:
Publication Date(Web):August 15, 2014
DOI:10.1021/bm501028c
Here we introduce a modified peptide-decorated polymeric nanoparticle (NP) for cancer cell targeting, which can deliver drugs, such as doxorubicin (Dox), to several kinds of cancer cells. Specifically, we employ a nucleolin-targeting NP, with a matrix based on a copolymer of acrylamide (AAm) and 2-carboxyethyl acrylate (CEA). The negatively charged co(CEA-AAm) NP was conjugated with a nucleolin-targeting F3 peptide using a highly efficient and specific copper(I) catalyzed azide–alkyne click reaction. F3 peptide binds to angiogenic tumor vasculatures and other nucleolin overexpressing tumor cells. Attaching F3 peptide onto the NP increases the NP uptake by the nucleolin-expressing glioma cell line 9L and the breast cancer cell line MCF-7. Notably, the F3-conjugated NPs show much higher uptake by the nucleolin-overexpressing glioma cell line 9L than that by the breast cancer cell line MCF-7, the latter having a lower expression of nucleolin on its plasma membrane surface. Moreover, the F3 peptide also dramatically enhances the uptake of co(CEA-AAm) NPs by the drug-resistant cell line NCI/ADR-RES. Also, with this F3-conjugated co(CEA-AAm) NP, a high loading and slow release of doxorubicin were achieved.
Co-reporter:Leshern Karamchand, Gwangseong Kim, Shouyan Wang, Hoe Jin Hah, Aniruddha Ray, Ruba Jiddou, Yong-Eun Koo Lee, Martin A. Philbert and Raoul Kopelman
Nanoscale 2013 vol. 5(Issue 21) pp:10327-10344
Publication Date(Web):22 Aug 2013
DOI:10.1039/C3NR00908D
Surface engineering of a hydrogel nanoparticle (NP) with the tumor-targeting ligand, F3 peptide, enhances both the NP's binding affinity for, and internalization by, nucleolin overexpressing tumor cells. Remarkably, the F3-functionalized NPs consistently exhibited significantly lower trafficking to the degradative lysosomes than the non-functionalized NPs, in the tumor cells, after internalization. This is attributed to the non-functionalized NPs, but not the F3-functionalized NPs, being co-internalized with Lysosome-associated Membrane Protein-1 (LAMP1) from the surface of the tumor cells. Furthermore, it is shown that the intracellular trafficking of the F3-functionalized NPs differs significantly from that of the molecular F3 peptides (untethered to NPs). This has important implications for designing effective, chemically-responsive, controlled-release and multifunctional nanodrugs for multi-drug-resistant cancers.
Co-reporter:Hyung Ki Yoon, Aniruddha Ray, Yong-Eun Koo Lee, Gwangseong Kim, Xueding Wang and Raoul Kopelman
Journal of Materials Chemistry A 2013 vol. 1(Issue 41) pp:5611-5619
Publication Date(Web):22 Aug 2013
DOI:10.1039/C3TB21060J
Indocyanine green (ICG) is an optical contrast agent commonly used for a variety of imaging applications. However, certain limitations of the free dye molecule, concerning its low stability, uncontrolled aggregation and lack of targeting ability, have limited its use. Presented here is a method of embedding ICG in a novel polymer–protein hybrid nanocarrier so as to overcome the above inherent drawbacks of the free molecule. The hybrid nanocarrier consists of a non-toxic and biocompatible polyacrylamide nanoparticle (PAA NP) matrix that incorporates human serum albumin (HSA). This nanocarrier was synthesized through pre-conjugation with HSA and amine functionalized monomer, followed by polymerization using biodegradable cross-linkers, in a water-in-oil emulsion. The ICG dye is loaded into the HSA conjugated PAA nanoparticles (HSA–PAA NPs) through post-loading. Compared to the PAA polymer matrix, the presence of hydrophobic pockets in the HSA–PAA NPs further increases the chemical and physical stability of ICG. This is manifested by lowering the chemical degradation rates under physiological conditions, as well as by improving the thermal- and photo-stability of the dye. A targeting moiety, F3–Cys peptide, was attached to the surface of the NPs, for selective delivery to specific cancer cell lines. The suitability of these NPs for optical imaging applications was demonstrated by performing fluorescence imaging on a rat gliosarcoma cell line (9L). We also present the photoacoustic response of the HSA–PAA NPs, used as imaging contrast agents, in the spectral window of 700 nm to 800 nm.
Co-reporter:Ariel Hecht, Patrick Commiskey, Nicholas Shah, Raoul Kopelman
Biosensors and Bioelectronics 2013 Volume 48() pp:26-32
Publication Date(Web):15 October 2013
DOI:10.1016/j.bios.2013.03.073
•Bead Assembly Magnetorotation is demonstrated as a viable signal transduction method.•Limit of detection for thrombin in buffer is 80 fM.•Portable laser-and-photodiode system demonstrated for microscope-free detection.•Fractal analysis demonstrated as a secondary signal transduction method.This paper demonstrates a proof-of-principle for a new signal transduction method for protein detection called Bead Assembly Magnetorotation (BAM). BAM is based on using the target protein to mediate the formation of aptamer-coated 1 μm magnetic beads into a bead assembly, formed at the bottom of a 1 μL hanging droplet. The size, shape and fractal dimension of this bead assembly all depend on the protein concentration. The protein concentration can be measured in two ways: by magnetorotation, in which the rotational period of the assembly correlates with the protein concentration, or by fractal analysis. Additionally, a microscope-free magnetorotation detection method is introduced, based on a simple laser apparatus built from standard laboratory components. In this paper, we chose to focus on the protein thrombin, a popular choice for proof-of-principle work in this field.
Co-reporter:Di Si, Tamir Epstein, Yong-Eun Koo Lee, and Raoul Kopelman
Analytical Chemistry 2012 Volume 84(Issue 2) pp:978
Publication Date(Web):November 28, 2011
DOI:10.1021/ac202521e
Ca2+ is a universal second messenger and plays a major role in intracellular signaling, metabolism, and a wide range of cellular processes. To date, one of the most successful approaches for intracellular Ca2+ measurement involves the introduction of optically sensitive Ca2+ indicators into living cells, combined with digital imaging microscopy. However, the use of free Ca2+ indicators for intracellular sensing and imaging has several limitations, such as nonratiometric measurement for the most-sensitive indicators, cytotoxicity of the indicators, interference from nonspecific binding caused by cellular biomacromolecules, challenging calibration, and unwanted sequestration of the indicator molecules. These problems are minimized when the Ca2+ indicators are encapsulated inside porous and inert polyacrylamide nanoparticles. We present PEBBLE nanosensors encapsulated with rhodamine-based Ca2+ fluorescence indicators. The rhod-2-containing PEBBLEs presented here show a stable sensing range at near-neutral pH (pH 6–9). Because of the protection of the PEBBLE matrix, the interference of protein-nonspecific binding to the indicator is minimal. The rhod-2 PEBBLEs give a nanomolar dynamic sensing range for both in-solution (Kd = 478 nM) and intracellular (Kd = 293 nM) measurements. These nanosensors are useful quantitative tools for the measurement and imaging of the cytosolic nanomolar free Ca2+ levels.
Co-reporter:Irene Sinn, Theodore Albertson, Paivo Kinnunen, David N. Breslauer, Brandon H. McNaughton, Mark A. Burns, and Raoul Kopelman
Analytical Chemistry 2012 Volume 84(Issue 12) pp:5250
Publication Date(Web):April 17, 2012
DOI:10.1021/ac300128p
The long turnaround time in antimicrobial susceptibility testing (AST) endangers patients and encourages the administration of wide spectrum antibiotics, thus resulting in alarming increases of multidrug resistant pathogens. A method for faster detection of bacterial proliferation presents one avenue toward addressing this global concern. We report on a label-free asynchronous magnetic bead rotation (AMBR) based viscometry method that rapidly detects bacterial growth and determines drug sensitivity by measuring changes in the suspension’s viscosity. With this platform, we observed the growth of a uropathogenic Escherichia coli isolate, with an initial concentration of 50 cells per drop, within 20 min; in addition, we determined the gentamicin minimum inhibitory concentration (MIC) of the E. coli isolate within 100 min. We thus demonstrated a label-free, microviscometer platform that can measure bacterial growth and drug susceptibility more rapidly, with lower initial bacterial counts than existing commercial systems, and potentially with any microbial strains.
Co-reporter:Shouyan Wang, Gwangseong Kim, Yong-Eun Koo Lee, Hoe Jin Hah, Manivannan Ethirajan, Ravindra K. Pandey, and Raoul Kopelman
ACS Nano 2012 Volume 6(Issue 8) pp:6843
Publication Date(Web):June 17, 2012
DOI:10.1021/nn301633m
We describe here the development of multifunctional nanocarriers, based on amine-functionalized biodegradable polyacrylamide nanoparticles (NPs), for cancer theranostics, including active tumor targeting, fluorescence imaging, and photodynamic therapy. The structural design involves adding primary amino groups and biodegradable cross-linkers during the NP polymerization, while incorporating photodynamic and fluorescent imaging agents into the NP matrix, and conjugating PEG and tumor-targeting ligands onto the surface of the NPs. The as-synthesized NPs are spherical, with an average diameter of 44 nm. An accelerated biodegradation study, using sodium hydroxide or porcine liver esterase, indicated a hydrogel polymer matrix chain collapse within several days. By using gel permeation chromatography, small molecules were detected, after the degradation. In vitro targeting studies on human breast cancer cells indicate that the targeted NPs can be transported efficiently into tumor cells. Incubating the multifunctional nanocarriers into cancer cells enabled strong fluorescence imaging. Irradiation of the photosensitizing drug, incorporated within the NPs, with light of a suitable wavelength, causes significant but selective damage to the impregnated tumor cells, but only inside the illuminated areas. Overall, the potential of polymeric-based NPs as biodegradable, multifunctional nanocarriers, for cancer theranostics, is demonstrated here.Keywords: cancer; imaging; multifunctional; nanoparticle; photodynamic therapy; polymer; targeting
Co-reporter:Raoul Kopelman
ACS Nano 2012 Volume 6(Issue 9) pp:7553
Publication Date(Web):September 13, 2012
DOI:10.1021/nn304119h
Nature’s molecular motors and nanomachines perform marvelous tasks, especially on the level of single cells. Can artificial ones compete? In this issue, You et al. demonstrate a photon-driven molecular machine where switching the color of the light switches the direction of motion of the molecular motor. While having inferior performance characteristics, this novel motor may become the forerunner of a new generation of sophisticated and practical competitors with Nature’s ancient, but highly important, nanomachines.
Co-reporter:Ariel Hecht, Anand Akshay Kumar, and Raoul Kopelman
Analytical Chemistry 2011 Volume 83(Issue 18) pp:7123
Publication Date(Web):August 1, 2011
DOI:10.1021/ac2014756
This paper presents a new signal transduction method, called label-acquired magnetorotation (LAM), for the measurement of the concentration of proteins in solution. We demonstrate the use of LAM to detect the protein thrombin using aptamers, with a limit of detection of 300 pM. LAM is modeled after a sandwich assay, with a 10 μm nonmagnetic “mother” sphere as the capture component and with 1 μm magnetic “daughter” beads as the labels. The protein-mediated attachment of daughter beads to the mother sphere forms a rotating sandwich complex. In a rotating magnetic field, the rotational frequency of a sandwich complex scales with the number of attached magnetic beads, which scales with the concentration of the protein present in solution. This paper represents the first instance of the detection of a protein using LAM.
Co-reporter:Irene Sinn, Paivo Kinnunen, Theodore Albertson, Brandon H. McNaughton, Duane W. Newton, Mark A. Burns and Raoul Kopelman
Lab on a Chip 2011 vol. 11(Issue 15) pp:2604-2611
Publication Date(Web):10 Jun 2011
DOI:10.1039/C0LC00734J
Inappropriate antibiotic use is a major factor contributing to the emergence and spread of antimicrobial resistance. The long turnaround time (over 24 hours) required for clinical antimicrobial susceptibility testing (AST) often results in patients being prescribed empiric therapies, which may be inadequate, inappropriate, or overly broad-spectrum. A reduction in the AST time may enable more appropriate therapies to be prescribed earlier. Here we report on a new diagnostic asynchronous magnetic bead rotation (AMBR) biosensor droplet microfluidic platform that enables single cell and small cell population growth measurements for applications aimed at rapid AST. We demonstrate the ability to rapidly measure bacterial growth, susceptibility, and the minimum inhibitory concentration (MIC) of a small uropathogenic Escherichia coli population that was confined in microfluidic droplets and exposed to concentrations above and below the MIC of gentamicin. Growth was observed below the MIC, and no growth was observed above the MIC. A 52% change in the sensor signal (i.e. rotational period) was observed within 15 minutes, thus allowing AST measurements to be performed potentially within minutes.
Co-reporter:Aniruddha Ray, Yong-Eun Koo Lee, Tamir Epstein, Gwangseong Kim and Raoul Kopelman
Analyst 2011 vol. 136(Issue 18) pp:3616-3622
Publication Date(Web):20 Jul 2011
DOI:10.1039/C1AN15046D
Intracellular pH mapping is of great importance as it plays a critical role in many cellular events. Also, in tissue, pH mapping can be an indicator for the onset of cancer. Here we describe a biocompatible, targeted, ratiometric, fluorescent, pH sensing nano-PEBBLE (Photonic Explorer for Biomedical use with Biologically Localized Embedding) that is based on two-photon excitation. Two-photon excitation minimizes the photobleaching and cell autofluorescence drastically, leading to an increase in the signal-to-noise ratio. PEBBLE nanosensors provide a novel approach for introducing membrane impermeant dyes, like HPTS, into cells. We use both non-targeted and F3 peptide targeted PEBBLE nanosensors for intracellular pH measurement of 9L cells. The intracellular measurements suggest that the non-targeted nanosensors are mostly trapped in endosomes, whereas the F3 peptide targeting enables them to escape/avoid these acidic compartments. Combining the advantages of pH sensitive PEBBLE nanoparticles, including their specific targeting, with the advantages of two-photon microscopy provides an attractive and promising prospect for non-invasive real-time monitoring of pH inside cancer cells and tissues.
Co-reporter:Hoe Jin Hah;Gwangseong Kim;Yong-Eun Koo Lee;Daniel A. Orringer;Oren Sagher;Martin A. Philbert
Macromolecular Bioscience 2011 Volume 11( Issue 1) pp:90-99
Publication Date(Web):
DOI:10.1002/mabi.201000231
Co-reporter:Ming Qin, Hoe Jin Hah, Gwangseong Kim, Guochao Nie, Yong-Eun Koo Lee and Raoul Kopelman
Photochemical & Photobiological Sciences 2011 vol. 10(Issue 5) pp:832-841
Publication Date(Web):09 Apr 2011
DOI:10.1039/C1PP05022B
The use of targeted nanoparticles (NPs) as a platform for loading photosensitizers enables selective accumulation of the photosensitizers in the tumor area, while maintaining their photodynamic therapy (PDT) effectiveness. Here two novel kinds of methylene blue (MB)-conjugated polyacrylamide (PAA) nanoparticles, MBI-PAA NPs and MBII-PAA NPs, based on two separate MB derivatives, are developed for PDT. This covalent conjugation with the NPs (i) improves the loading of MB, (ii) prevents any leaching of MB from the NPs and (iii) protects the MB from the effects of enzymes in the biological environment. The loading of MB into these two kinds of NPs was controlled by the input amount, resulting in concentrations with optimal singlet oxygen production. For each of the MB-NPs, the highest singlet oxygen production was found for an MB loading of around 11 nmol mg−1. After attachment of F3 peptide groups, for targeting, each of these NPs was taken up, selectively, by MDA-MB-435 tumor cells, in vitro. PDT tests demonstrated that both kinds of targeted NPs resulted in effective tumor cell kill, following illumination, while not causing dark toxicity.
Co-reporter:Aniruddha Ray;Xueding Wang;Yong-Eun Koo Lee;Hoe Jin Hah;Gwangseong Kim
Nano Research 2011 Volume 4( Issue 11) pp:1163-1173
Publication Date(Web):2011 November
DOI:10.1007/s12274-011-0166-1
Co-reporter:Gwangseong Kim, Yong-Eun Koo Lee, Hao Xu, Martin A. Philbert and Raoul Kopelman
Analytical Chemistry 2010 Volume 82(Issue 6) pp:2165
Publication Date(Web):February 17, 2010
DOI:10.1021/ac9024544
Reactive oxygen species (ROS) are ubiquitous in life and death processes of cells (Finkel, T.; Holbrook, N. J. Nature 2000, 408 (6809), 239−247), with a major role played by the most stable ROS, hydrogen peroxide (H2O2). However, the study of H2O2 in live cells has been hampered by the absence of selective probes. Described here is a novel nanoprobe (“nanoPEBBLE”) with dramatically improved H2O2 selectivity. The traditional molecular probe, 2′,7′-dichlorofluorescin (DCFH), which is also sensitive to most other ROS, was empowered with high selectivity by a nanomatrix that blocks the interference from all other ROS (hydroxyl radical, superoxide, nitric oxide, peroxynitrite, hypochlorous acid, and alkylperoxyl radical), as well as from enzymes such as peroxidases. The blocking is based on the combination of multiple exclusion principles: time barrier, hydrophobic energy barrier, and size barrier. However, H2O2 sensitivity is maintained down to low nanomolar concentrations. The surface of the nanoprobe was engineered to address biological applications, and the power of this new nanoPEBBLE is demonstrated by its use on RAW264.7 murine macrophages. These nanoprobes may provide a powerful chemical detection/imaging tool for investigating biological mechanisms related to H2O2 or other species, with high spatial and temporal resolution.
Co-reporter:Yong-Eun Koo Lee, Elyse E. Ulbrich, Gwangseong Kim, Hoejin Hah, Christen Strollo, Wenzhe Fan, Rajan Gurjar, SangMan Koo, and Raoul Kopelman
Analytical Chemistry 2010 Volume 82(Issue 20) pp:8446
Publication Date(Web):September 17, 2010
DOI:10.1021/ac1015358
The development of sensors for noninvasive determination of oxygen levels in live cells and tissues is critical for the understanding of cellular functions, as well as for monitoring the status of disease, such as cancer, and for predicting the efficacy of therapy. We describe such nontoxic, targeted, and ratiometric 30 nm oxygen nanosensors made of polyacrylamide hydrogel, near-infrared (NIR) luminescent dyes, and surface-conjugated tumor-specific peptides. They enabled noninvasive real-time monitoring of oxygen levels in live cancer cells under normal and hypoxic conditions. The required sensitivity, brightness, selectivity, and stability were achieved by tailoring the interaction between the nanomatrix and indicator dyes. The developed nanosensors may become useful for in vivo oxygen measurements.
Co-reporter:De Gao, Hao Xu, Martin A. Philbert and Raoul Kopelman
Nano Letters 2008 Volume 8(Issue 10) pp:3320-3324
Publication Date(Web):September 13, 2008
DOI:10.1021/nl8017274
One of the most significant obstacles for systematic delivery of nanopayloads is the foreign particle clearance by the mononuclear phagocyte system (MPS). The majority of biocompatible nanopayloads with charged groups on their surface cannot fully evade the clearance by MPS during systemic circulation. For safe and effective targeted nanodrug delivery in vivo, we describe a novel approach for evading the macrophage clearance. We demonstrate that neutral and hydrophilic materials can effectively evade the macrophage uptake and also quickly degrade into bioeliminable fragments. We show that there is no opsonization effect and no toxic effect on living cells. In addition, the payloads are stable in an aqueous environment, and they can release drugs in a cellular environment. These results suggest that the unique properties of this kind of payloads may make them useful for designing new drug delivery systems.
Co-reporter:Rachela Popovtzer, Ashish Agrawal, Nicholas A. Kotov, Aron Popovtzer, James Balter, Thomas. E. Carey and Raoul Kopelman
Nano Letters 2008 Volume 8(Issue 12) pp:4593-4596
Publication Date(Web):November 5, 2008
DOI:10.1021/nl8029114
X-ray based computed tomography (CT) is among the most convenient imaging/diagnostic tools in hospitals today in terms of availability, efficiency, and cost. However, in contrast to magnetic resonance imaging (MRI) and various nuclear medicine imaging modalities, CT is not considered a molecular imaging modality since targeted and molecularly specific contrast agents have not yet been developed. Here we describe a targeted molecular imaging platform that enables, for the first time, cancer detection at the cellular and molecular level with standard clinical CT. The method is based on gold nanoprobes that selectively and sensitively target tumor selective antigens while inducing distinct contrast in CT imaging (increased X-ray attenuation). We present an in vitro proof of principle demonstration for head and neck cancer, showing that the attenuation coefficient for the molecularly targeted cells is over 5 times higher than for identical but untargeted cancer cells or for normal cells. We expect this novel imaging tool to lead to significant improvements in cancer therapy due to earlier detection, accurate staging, and microtumor identification.
Co-reporter:De Gao Dr.;Hao Xu Dr.;Martin A. Philbert
Angewandte Chemie 2007 Volume 119(Issue 13) pp:
Publication Date(Web):20 FEB 2007
DOI:10.1002/ange.200603927
Lizenz zum Töten: Ein Verfahren zur Herstellung ultrafeiner hydrophiler Polyacrylamid-Nanopartikel wurde entwickelt, die meta-Tetra(hydroxyphenyl)chlorin (mTHPC) einschließen. Ratten-C6-Gliomzellen, die IR-Licht ausgesetzt waren, wurden in Gegenwart der mTHPC einschließenden Nanopartikel zerstört (rot), während nicht bestrahlte Zellen am Leben blieben (grün).
Co-reporter:De Gao Dr.;Hao Xu Dr.;Martin A. Philbert
Angewandte Chemie International Edition 2007 Volume 46(Issue 13) pp:
Publication Date(Web):20 FEB 2007
DOI:10.1002/anie.200603927
Licensed to kill: A method for obtaining ultrafine hydrophilic polyacrylamide-based nanoparticles that encapsulate meta-tetra(hydroxyphenyl)chlorin (mTHPC) has been developed. Rat C6 glioma cells exposed to infrared light were killed (red) in the presence of the mTHPC-encapsulating nanoparticles while the cells without exposure to light were still alive (green).
Co-reporter:James P. Sumner, Nissa M. Westerberg, Andrea K. Stoddard, Tamiika K. Hurst, Michele Cramer, Richard B. Thompson, Carol A. Fierke, Raoul Kopelman
Biosensors and Bioelectronics 2006 Volume 21(Issue 7) pp:1302-1308
Publication Date(Web):15 January 2006
DOI:10.1016/j.bios.2005.04.023
The wild type form of Red fluorescent protein (DsRed), an intrinsically fluorescent protein found in tropical corals, is found to be highly selective, reversible and sensitive for both Cu+ and Cu2+, with a nanomolar detection limit. The selectivity towards these ions is retained even in the presence of other heavy metal ions. The Kd values for monovalent and divalent copper, based on single binding isotherms, are 450 and 540 nM, respectively. The wild type DsRed sensitivity to Cu2+ (below 1 ppb) is seven orders of magnitude better than that of the related wild type Green Fluorescent protein (GFP), and it is even 40 times more sensitive than engineered mutants of GFP. Potential binding sites have been proposed, based on amino acid sequences for copper binding and the distance from the chromophore, with the aid of computer modeling.
Co-reporter:James P. Sumner, Nissa M. Westerberg, Andrea K. Stoddard, Carol A. Fierke, Raoul Kopelman
Sensors and Actuators B: Chemical 2006 Volume 113(Issue 2) pp:760-767
Publication Date(Web):27 February 2006
DOI:10.1016/j.snb.2005.07.028
The red fluorescent protein (DsRed) has typically been used as either a fluorescent tag or FRET acceptor, but here, we detail its use as a recognition element for Cu2+ and Cu+ in a fluorescent photonic explorer for bioanalysis with biologically localized embedding (PEBBLE) nanosensor. DsRed and the reference dye Alexa Fluor 488 have been encapsulated within a polyacrylamide matrix by a microemulsion polymerization process, to produce spherical, ratiometric, 80 nm-sized sensors, which allow for spatially resolved real-time measurements. These nanobiosensors have excellent selectivity and sensitivity towards copper ions, with a detectable range in the nanomolar (ppb) regime, even in the presence of other divalent and heavy metal ions. The nanosensors are both photostable and reversible, which allows for continuous monitoring.
Co-reporter:Edwin J. Park, Kendra R. Reid, Wei Tang, Robert T. Kennedy and Raoul Kopelman
Journal of Materials Chemistry A 2005 vol. 15(Issue 27-28) pp:2913-2919
Publication Date(Web):05 May 2005
DOI:10.1039/B502981C
A sensor platform was developed for the detection of inter- and intra-cellular dissolved oxygen, using a fiber optic probe. The design and fabrication of the oxygen fiber optic sensor are based on the excellent luminescence quenching properties of the near-infrared oxygen sensitive platinum(II) octaethylporphine ketone (PtOEPK) dye. Together with a reference dye, octaethyl porphyrin (OEP) or bodipy maleimide 577/618, the dye was entrapped, in an easily renewable liquid polymer matrix, made of polyvinyl chloride, including the plastisizing agent bis(2-ethylhexyl) sebacate (DOS). Multi-mode fibers were pulled down to submicron dimensions and a dip coating procedure was used to apply the sensing membrane film to the tip. This sensor was fully characterized and exhibits excellent reversibility, minimal photobleaching and leaching, and fast response times. The resulting oxygen sensor is one of the most sensitive optical oxygen sensors to date, with good linearity in the Stern–Volmer plot calibrations. This sensor is ultimately intended for biological inter- and intra-cellular measurements.
Co-reporter:James P. Sumner and Raoul Kopelman
Analyst 2005 vol. 130(Issue 4) pp:528-533
Publication Date(Web):25 Feb 2005
DOI:10.1039/B414189J
Molecular Probes' Alexa Fluor dyes are generally used for biological labeling because of their ideal fluorescent properties, but here we detail Alexa Fluor 488's nanomolar sensitivity to free iron. Furthermore, the dye has been encapsulated into a polymer nanosphere by a microemulsion method, producing <100 nm particles. These nanosensors, PEBBLEs (Probe Encapsulated By Biologically Localized Embedding) have micromolar sensitivity and are non-responsive to other metal ions of biological interest.
Co-reporter:Wei Tang;Hao Xu;Martin A. Philbert
Photochemistry and Photobiology 2005 Volume 81(Issue 2) pp:242-249
Publication Date(Web):30 APR 2007
DOI:10.1111/j.1751-1097.2005.tb00181.x
This article presents the development and characterization of nanoparticles loaded with methylene blue (MB), which are designed to be administered to tumor cells externally and deliver singlet oxygen (1O2) for photodynamic therapy (PDT), i.e. cell kill via oxidative stress to the membrane. We demonstrated the encapsulation of MB, a photosensitizer (PS), in three types of sub-200 nm nanoparticles, composed of polyacrylamide, sol-gel silica and organically modified silicate (ORMOSIL), respectively. Induced by light irradiation, the entrapped MB generated 1O2), and the produced 1O2 was measured quantitatively with anthracene-9, 10-dipropionic acid, disodium salt, to compare the effects of different matrices on 1O2 delivery. Among these three different kinds of nanoparticles, the polyacrylamide nanoparticles showed the most efficient delivery of 1O2 but its loading of MB was low. In contrast, the sol-gel nanoparticles had the best MB loading but the least efficient 1O2 delivery. In addition to investigating the matrix effects, a preliminary in vitro PDT study using the MB-loaded polyacrylamide nanoparticles was conducted on rat C6 glioma tumor cells with positive photodynamic results. The encapsulation of MB in nanoparticles should diminish the interaction of this PS with the biological milieu, thus facilitating its systemic administration. Furthermore, the concept of the drug-delivering nanoparticles has been extended to a new type of dynamic nanoplatform (DNP) that only delivers 1O2. This DNP could also be used as a targeted multifunctional platform for combined diagnostics and therapy of cancer.
Co-reporter:Raoul Kopelman;Yong-Eun Lee Koo;Youfu Cao;Sang Man Koo
Photochemistry and Photobiology 2005 Volume 81(Issue 6) pp:1489-1498
Publication Date(Web):30 APR 2007
DOI:10.1562/2005-05-18-RA-532
Ratiometric photonic explorers for bioanalysis with biologically localized embedding (PEBBLE) nanoprobes have been developed for singlet oxygen, using organically modified silicate (ORMOSIL) nanoparticles as the matrix. A crucial aspect of these ratiometric singlet-oxygen fluorescent probes is their minute size. The ORMOSIL nanoparticles are prepared via a sol-gel–based process and the average diameter of the resultant particles is about 160 nm. These sensors incorporate the singlet-oxygen–sensitive 9,10-dimethyl anthracene as an indicator dye and a singlet-oxygen–insensitive dye, octaethylporphine, as a reference dye for ratiometric fluorescence-based analysis. We have found experimentally that these nanoprobes have much better sensitivity than does the conventional singlet-oxygen–free dye probe, anthracene-9, 10-dipropionic acid disodium salt. The much longer lifetime of singlet oxygen in the ORMOSIL matrix, compared to aqueous solutions, in addition to the relatively high singlet oxygen solubility because of the highly permeable structure and the hydrophobic nature of the outer shell of the ORMOSIL nanoparticles, results in an excellent overall response to singlet oxygen. These nanoprobes have been used to monitor the singlet oxygen produced by “dynamic nanoplatforms” that were developed for photodynamic therapy. The singlet oxygen nanoprobes could potentially be used to quantify the singlet oxygen produced by macrophages.
Co-reporter:Sarah M Buck, Yong-Eun Lee Koo, Ed Park, Hao Xu, Martin A Philbert, Murphy A Brasuel, Raoul Kopelman
Current Opinion in Chemical Biology 2004 Volume 8(Issue 5) pp:540-546
Publication Date(Web):October 2004
DOI:10.1016/j.cbpa.2004.08.011
Nanosized photonic explorers for bioanalysis with biologically localized embedding (PEBBLEs) have been created for the intracellular monitoring of small analytes (e.g. H+, Ca2+, Mg2+, Zn2+, O2, K+, Na+, Cl−, OH and glucose). The probes are based on the inclusion of fluorescent analyte-sensitive indicator dyes and analyte-insensitive reference dyes in a polymer (polyacrylamide, polydecylmethacrylate) or sol-gel (silica, ormosil) nanoparticle. The probes are ratiometric, reversible and protected from interaction with the cellular environment, a quality which is of benefit to the integrity of both the cell and the sensor functionalities. Herein we describe two types of PEBBLE sensors, direct measurement sensors and ion correlation sensors, as well as the use of these PEBBLEs in intracellular sensing.
Co-reporter:Martin A. Philbert;Sarah M. Buck;Murphy Brasuel;Brian D. Ross;Hao Xu;Alnawaz Rehemtulla
Israel Journal of Chemistry 2004 Volume 44(Issue 1‐3) pp:317-337
Publication Date(Web):8 MAR 2010
DOI:10.1560/WA5H-KBGV-PR13-NEVN
PEBBLEs (Probes Encapsulated By Biologically Localized Embedding) are submicron-sized optical sensors designed specifically for minimally invasive analyte monitoring in viable single cells, with applications for real-time analysis of drug, toxin, and environmental effects on cell function. PEBBLE nanosensor is a general term that describes a family of matrices and nano-fabrication techniques used to miniaturize many existing optical sensing technologies. The main classes of PEBBLE nanosensors are based on matrices of cross-linked polyacrylamide, cross-linked poly(decyl methacrylate), and sol-gel silica. These matrices have been used to fabricate sensors for H+, Ca2+, K+, Na+, Mg2+, Zn2+, Cu2+, Cl−, O2, NO, and glucose that range from 20 nm to 600 nm in diameter. A number of delivery techniques have been used successfully to deliver PEBBLE nanosensors into mouse oocytes, rat alveolar macrophages, rat C6-glioma, and human neuroblastoma cells. PEBBLEs with several newly emerging directions in design and applications, going from intracellular imaging to in vivo actuating and targeting, are also described. They include photonic, magnetic, and stochastic control and modulation of photo-excitation, and also targeted nano-platforms for photodynamic therapy of brain cancers, as well as contrast enhancement of the MRI for monitoring such therapy.
Co-reporter:Sarah M Buck, Hao Xu, Murphy Brasuel, Martin A Philbert, Raoul Kopelman
Talanta 2004 Volume 63(Issue 1) pp:41-59
Publication Date(Web):10 May 2004
DOI:10.1016/j.talanta.2003.12.048
This review discusses the development and recent advances of probes encapsulated by biologically localized embedding (PEBBLEs), and in particular the application of PEBBLEs as ion sensors. PEBBLEs allow for minimally intrusive sensing of ions in cellular environments due to their small size (20 to 600 nm in diameter) and protect the sensing elements (i.e. fluorescent dyes) by encapsulating them within an inert matrix. The selectivity and sensitivity of these nanosensors are comparable to those of macroscopic ion selective optodes, and electrodes, while the response time and absolute detection limit are significantly better. This paper discusses the principles guiding PEBBLE design including synthesis, characterization, diversification, the advantages and limitations of the sensors, cellular applications and future directions of PEBBLE research.
Co-reporter:Murphy G. Brasuel, Terry J. Miller, Raoul Kopelman and Martin A. Philbert
Analyst 2003 vol. 128(Issue 10) pp:1262-1267
Publication Date(Web):04 Sep 2003
DOI:10.1039/B305254K
The first nanometer scale anion sensing fluorescent spherical nanosensors, or PEBBLEs (probes encapsulated by biologically localized embedding) have been developed for the intracellular monitoring of chloride. The general scheme for the polymerization and introduction of sensing components creates a matrix that allows for the utilization of the highly selective ionophores used in poly(vinyl chloride) and poly(decyl methacrylate) ion-selective electrodes. We have demonstrated that our previously developed scheme for cation sensors can be utilized to tailoring selective submicron sensors for use in intracellular measurements of biologically relevant anions for which selective enough fluorescent probes do not exist. Three schemes were attempted for the development of chloride sensitive PEBBLEs. The first two used the Chloride ionophore indium(III) octaethylporphyrin chloride (In(OEP)Cl) (1) as an ionophore working in tandem with a chromoionophore and (2) as a chromoionophore with a peak shift generated by chloride mediated breaking of hydroxide ion-bridged porphyrin dimer. The third method used the optically silent Chloride ionophore III (ETH 9033) working in tandem with chromoionophore III (ETH 5350) to indirectly monitor Cl− activity by reporting the H+ coextracted into the matrix. Method 3 gave the most promising results, at a pH of 7.2 these PEBBLEs have a limit of detection of 0.2 mM Cl− with a linear dynamic range of 0.4 mM–190 mM Cl−. These PEBBLEs were delivered into C6 glioma cells, utilizing a gene gun, and intracellular chloride levels were monitored during ion-channel stimulation by kainic acid.
Co-reporter:Fei Yan;Hao Xu;Eric E. Monson
Journal of Biomedical Materials Research Part A 2003 Volume 66A(Issue 4) pp:870-879
Publication Date(Web):12 AUG 2003
DOI:10.1002/jbm.a.10057
Monodisperse, spherical, polyethylene glycol (PEG)–coated silica nanoparticles have been prepared at room temperature and characterized for the purpose of biomedical applications. The particles were synthesized by the hydrolysis of tetramethyl orthosilicate (TMOS) in alcohol media under catalysis by ammonia, and their size can range from about 50–350 nm in diameter. We studied the particle size and size distribution using a scanning electron microscope (SEM) and an asymmetric field-flow fractionation (AFFF) multiangle static light-scattering instrument. The chemical and/or physical binding of PEG to the silica nanoparticles was studied by infrared spectroscopy, and the weight percentage of PEG attached to the particles was quantified. The PEG-coated silica nanoparticles showed enhanced colloidal stability when redispersed into aqueous solutions from the dried state as a result of the steric stabilization function of the PEG polymer grafted on the surface of particles. A nonspecific protein-binding test was also carried out to show that the PEG coating can help reduce the protein adsorption onto the surface of the particles, relating to the biocompatibility of these PEG-coated particles. Also, the inclusion of magnetic nanoparticles into the silica particles was shown as an example of the possible applications of PEG-coated silica particles. These silica nanoparticles, as a matrix for encapsulation of certain reagents, have potential for applications to in vivo diagnosis, analysis, and measurements inside intact biologic systems. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 870–879, 2003
Co-reporter:Fei Yan
Photochemistry and Photobiology 2003 Volume 78(Issue 6) pp:587-591
Publication Date(Web):1 MAY 2007
DOI:10.1562/0031-8655(2003)0780587TEOMIS2.0.CO2
This study relates to nanoparticle (NP) platforms that attach to tumor cells externally and only deliver singlet oxygen for photodynamic therapy (PDT) while conserving the embedded photosensitizers (PS). As a model, we demonstrate the successful embedding of the PS meta-tetra(hydroxyphenyl)-chlorin (m-THPC) in NP that are based on a sol–gel silica matrix and also show its positive effect on the singlet oxygen production. The embedding of m-THPC inside silica NP is accomplished by a modified Stöber sol–gel process, in which (3-aminopropyl)-triethoxysilane is introduced during the reaction. Singlet oxygen delivery by the targetable photodynamic NP exceeds that from free PS molecules. In the physiological pH range, there is no significant pH-induced decrease in the fluorescence of m-THPC embedded in silica NP, which might otherwise affect the efficiency of PDT.
Co-reporter:Hao Xu, Jonathan W. Aylott and Raoul Kopelman
Analyst 2002 vol. 127(Issue 11) pp:1471-1477
Publication Date(Web):27 Sep 2002
DOI:10.1039/B202782H
Polyacrylamide-based, ratiometric, spherical, optical nanosensors, or polyacrylamide PEBBLEs (Probes Encapsulated By Biologically Localized Embedding), have been fabricated, aimed at real-time glucose imaging in intact biological systems, i.e. living cells. These nanosensors are prepared using a microemulsion polymerization process, and their average size is about 45 nm in diameter. The sensors incorporate glucose oxidase (GOx), an oxygen sensitive fluorescent indicator (Ru[dpp(SO3Na)2]3)Cl2, and an oxygen insensitive fluorescent dye, Oregon Green 488-dextran or Texas Red-dextran, as a reference for the purpose of ratiometric intensity measurements. The enzymatic oxidation of glucose to gluconic acid results in the local depletion of oxygen, which is measured by the oxygen sensitive ruthenium dye. The small size and inert matrix of these sensors allows them to be inserted into living cells with minimal physical and chemical perturbations to their biological functions. The PEBBLE matrix protects the enzyme and fluorescent dyes from interference by proteins in cells, enabling reliable in vivo chemical analysis. Conversely, the matrix also significantly reduces the toxicity of the indicator and reference dyes to the cells, so that a larger variety of dyes can be used in optimal fashion. Furthermore, the PEBBLE matrix enables the synergistic approach in which there is a steady state of local oxygen consumption, and this cannot be achieved by separately introducing free enzyme and dyes into a cell. The work presented here describes the production and characterization of glucose sensitive PEBBLEs, and their potential for intracellular glucose measurements. The sensor response is determined in terms of the linear range, ratiometric operation, response time, sensor stability, reversibility and immunity to interferences.
Co-reporter:James P. Sumner, Jonathan W. Aylott, Eric Monson and Raoul Kopelman
Analyst 2002 vol. 127(Issue 1) pp:11-16
Publication Date(Web):04 Dec 2001
DOI:10.1039/B108568A
The development and characterisation of a fluorescent optical PEBBLE (Probe Encapsulated By Biologically Localised Embedding) nanosensor for the detection of zinc is detailed. A ratiometric sensor has been fabricated that incorporates two fluorescent dyes; one is sensitive to zinc and the other acts as a reference. The sensing components are entrapped within a polymer matrix by a microemulsion polymerisation process that produces spherical sensors that are in the size region of 20 to 200 nm. Cellular measurements are made possible by the small sensor size and the biocompatibility of the matrix. The effects of reversibility, photobleaching and leaching have been examined, as well as the selectivity towards zinc over other cellular ions such as Na+, Ca2+, K+, and Mg2+. The dynamic range of these sensors was found to be 4 to 50 μM Zn2+ with a linear range from 15 to 40 μM. The response time for the PEBBLE is less than
4 s and the sensor is reversible. In addition, the nanosensors are photostable and leaching from the matrix, determined using a novel method, is minimal. These sensors are capable of real-time inter- and intra-cellular imaging and are insensitive to interference from proteins.
Co-reporter:Yvan Wenger, Randal J. Schneider II, G. Ramachandra Reddy, Raoul Kopelman, Olivier Jolliet, Martin A. Philbert
Toxicology and Applied Pharmacology (15 March 2011) Volume 251(Issue 3) pp:181-190
Publication Date(Web):15 March 2011
DOI:10.1016/j.taap.2010.11.017
A variety of polymer nanoparticles (NP) are under development for imaging and therapeutic use. However, little is known about their behavior. This study examined pharmacokinetics, distribution and elimination of stable polyacrylamide (PAA) nanoparticles (~ 31 nm average diameter). PAA NPs and polyethylene glycol-coated PAA NPs were injected into the tail veins of healthy male rats. Blood, tissues and excreta were collected at times ranging from 5 min to 120 h and their radioactive content was quantified. A mathematical model was then applied to analyze the distribution dynamics of both NPs. Elimination from the blood could be accounted for by a quick but finite relocation to the major organs (about 20%, 0.6 to 1.3 h half-lives), and a slower distribution to the carcass (about 70%, 35 to 43 h half-lives). Excreted urinary levels correlated with blood concentrations. Combined cumulative urinary and fecal output accounted for less than 6% of the dose at 120 h. Compared to five other polymeric nanoparticles, the studied particles are at the highest half-lives and Area Under the Curve (4000 to 5000%-h). These two parameters decrease by three orders of magnitude when nanoparticle size increases from the 30 nm range up to 250 nm. For similar sizes, pegylated nanoparticles are more persistent in the blood than non-pegylated ones, but this difference is much smaller in the 30 nm and relatively high dose range than above 100 nm. Persistence of PAA NPs is not associated with acute toxicity signs as measured by typical serum markers of inflammation and cellular damage.
Co-reporter:Katherine M. Tyner, Raoul Kopelman, Martin A. Philbert
Biophysical Journal (15 August 2007) Volume 93(Issue 4) pp:
Publication Date(Web):15 August 2007
DOI:10.1529/biophysj.106.092452
Previously, all biological measurements of intracellular electric fields (E fields), using voltage dyes or patch/voltage clamps, were confined to cellular membranes, which account for <0.1% of the total cellular volume. These membrane-dependent techniques also frequently require lengthy calibration steps for each cell or cell type measured. A new 30-nm “photonic voltmeter”, 1000-fold smaller than existing voltmeters, enables, to our knowledge, the first complete three-dimensional E field profiling throughout the entire volume of living cells. These nanodevices are calibrated externally and then applied for E field determinations inside any live cell or cellular compartment, with no further calibration steps. The results indicate that the E fields from the mitochondrial membranes penetrate much deeper into the cytosol than previously estimated, indicating that, electrically, the cytoplasm cannot be described as a simple homogeneous solution, as often approximated, but should rather be thought of as a complex, heterogeneous hydrogel, with distinct microdomains.
Co-reporter:Hyung Ki Yoon, Aniruddha Ray, Yong-Eun Koo Lee, Gwangseong Kim, Xueding Wang and Raoul Kopelman
Journal of Materials Chemistry A 2013 - vol. 1(Issue 41) pp:NaN5619-5619
Publication Date(Web):2013/08/22
DOI:10.1039/C3TB21060J
Indocyanine green (ICG) is an optical contrast agent commonly used for a variety of imaging applications. However, certain limitations of the free dye molecule, concerning its low stability, uncontrolled aggregation and lack of targeting ability, have limited its use. Presented here is a method of embedding ICG in a novel polymer–protein hybrid nanocarrier so as to overcome the above inherent drawbacks of the free molecule. The hybrid nanocarrier consists of a non-toxic and biocompatible polyacrylamide nanoparticle (PAA NP) matrix that incorporates human serum albumin (HSA). This nanocarrier was synthesized through pre-conjugation with HSA and amine functionalized monomer, followed by polymerization using biodegradable cross-linkers, in a water-in-oil emulsion. The ICG dye is loaded into the HSA conjugated PAA nanoparticles (HSA–PAA NPs) through post-loading. Compared to the PAA polymer matrix, the presence of hydrophobic pockets in the HSA–PAA NPs further increases the chemical and physical stability of ICG. This is manifested by lowering the chemical degradation rates under physiological conditions, as well as by improving the thermal- and photo-stability of the dye. A targeting moiety, F3–Cys peptide, was attached to the surface of the NPs, for selective delivery to specific cancer cell lines. The suitability of these NPs for optical imaging applications was demonstrated by performing fluorescence imaging on a rat gliosarcoma cell line (9L). We also present the photoacoustic response of the HSA–PAA NPs, used as imaging contrast agents, in the spectral window of 700 nm to 800 nm.
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