Multifunctional upconversion nanoparticles (UCNPs) that can be implemented in theranostic applications are particularly attractive scaffolds for precise drug delivery. However, most of the current methods for drug formulation are technically complicated, thereby impeding their use in the clinic. Here, we report on the preparation of a lipophilic cytotoxic prodrug-integrated and polyethylene glycol (PEG)-cloaked UCNPs scaffold through a facile one-pot supramolecular approach. By choosing 7-ethyl-10-hydroxycamptothecin (SN38)-derived prodrug 1 as a model chemotherapeutic, we show that this lipophilic prodrug can be feasibly self-assembled onto the surface of UCNPs, which are cooperatively solubilized by PEGylated phospholipids. The resulting SN38 prodrug 1-encapsulated UCNPs (designated 1@pUCNPs) produce a stable colloidal system in aqueous solution, making it suitable for intravenous injection. The SN38 drug loading capacity in pUCNPs is as high as ∼12.3 wt%, and a sustained drug release profile is observed, indicating that the drug payloads can be transported to targeted tumor sites via the enhanced permeability and retention (EPR) effect. Upconversion luminescence (UCL) imaging, including in vivo and ex vivo imaging, suggests that the drug-loaded pUCNPs remain stable in tumors over a long time and preferentially accumulate in tumors presumably via the EPR effect. Furthermore, the 1@pUCNPs show superior therapeutic outcomes compared with the clinically approved SN38 prodrug CPT-11 in the Bcap-37 mouse model of breast cancer. Collectively, our results demonstrate that pUCNPs facilely constructed in a one-pot self-assembly manner may be used as a versatile platform, enabling synchronous in vivo delivery of poorly water-soluble drugs and tumor imaging.

•A microfluidic platform is developed for living Drosophila embryo's observation.•The embryo's anterior and posterior halves can be controlled at different environments.•Temperature gradients were created across the embryo by laminar flow.•Thermal gradient would result in asynchronous development of the two halves of the embryos.•The difference may be related to a check point located in the anterior half of the embryo.It is of great importance to understand biochemical system's behavior toward environmental perturbation during the development of living organisms. Here a microfluidic platform for Drosophila embryo's online development and observation is presented. The system is capable of developing the embryo's anterior and posterior halves controlled at different temperature environments, and it can be easily coupled with a confocal microscope for real-time image acquisition. The microfluidic chip is consisted of a polymethylmethacrylate (PMMA) substrate with a thickness of 4.0 mm and a polydimethylsiloxane (PDMS) cover designed with a typical ‘Y’ channel with a depth of 400 μm, width of 800 μm. Temperature gradients were created across the anterior half and posterior half of the embryo by utilizing two streams of laminar flow with different temperatures. It was found that thermal gradient would result in asynchronous development of the two halves of the embryos, and the developing difference was related to the direction of thermal gradient. This may result from the presence of an unknown mechanism located in the anterior half of the embryo, which oversees nuclear division synchronicity. These observations would help better understand compensatory mechanisms of Drosophila embryo's development under environmental perturbations.Temperature gradients would result in asynchronous development of the two halves of Drosophila embryos, and the development difference was related to the direction of thermal gradients. It implies that there may be an unknown mechanism located in the anterior half of the embryo, which oversees nuclear division synchronicity.Download high-res image (196KB)Download full-size image

Paper-based microfluidic devices (μPAD) are a burgeoning platform of microfluidic analysis technology. The method described herein is for use in undergraduate and high school chemistry laboratories. A simple and convenient μPAD was fabricated by easy patterning of filter paper using a permanent marker pen. The usefulness of the device was demonstrated by determination of nitrite ion concentration employing a colorimetric assay. The results for real sample detection using this μPAD were satisfactory and show promise for use in other applications.

Folic acid (or folate, FA) has attracted considerable attention for cancer therapy. As one small molecule, its receptor (folate receptor, FR) is significantly overexpressed on the surface of many human tumor cells compared with normal cells. In this work, physical and chemical coupled modification method, that is the combination of nanoimprinting technique and graft polymerization, was adopted to modify FA on nanopatterned polydimethylsiloxane (PDMS) surface for possible application in micro-nanofluidic cytology. The surface property of differently treated PDMS was characterized by FTIR, AFM and contact angle measurement. AO/PI double staining, cell counting and MTT method were performed to examine the potential influence of FA modified nanopatterned PDMS on human cervical carcinoma (HeLa) cell behavior. Both FA modification and nanostructure have positive effect on the growth and viability of HeLa cells. It is the first time that the small molecule-folic acid was used to immobilize on the surface of PDMS in order to improve its surface property.

Extremely thin SnO2 nanosheets with high surface area were fabricated through a one-pot hydrothermal method. In this work, gas sensing property of the SnO2 nanosheets was studied. SnO2–Pd–Au mixed thin films were prepared by electroless deposition of Pd, Au, and nanostructured SnO2 onto the surface of a high resistance alumina substrate. The whole fabrication process was carried out at room temperature without any thermal treatment required. The films deposited on the alumina substrate were characterized by SEM and EDS. The co-deposited Au improved the electric conductance of the sensing film. A relatively large amount of Pd (Pd/Sn ratio around 1:1) was obtained for the film instead of the usually low doping value of Pd (∼0.1% level) for SnO2 hydrogen sensor. It has been found that the SnO2–Pd–Au composite film sensor has fast response in the range of 134–1469 ppm toward hydrogen gas at room temperature. The sensor also shows good stability and repeatability. Effects of annealing condition of the sensing film on H2 gas sensing performance was investigated as well. A possible machnism for SnO2–Pd room temperature hydrogen sensing is proposed.Highlights► Extremely thin SnO2 nanosheets with high surface area were fabricated. ► SnO2–Pd mixed thin films were prepared by electroless deposition with Au. ► The thin film shows fast response toward hydrogen in a wide concentration range. ► The sensing material is particularly suitable for room temperature detection for H2. ► Both SnO2 and Pd play important roles in the sensing mechanism.

A simple three-dimensional (3D) hydrodynamic focusing microfluidic device integrated with continuous sampling, rapid dynamic lysis, capillary electrophoretic (CE) separation and detection of intracellular content is presented. One of the major difficulties in microfluidic cell analysis for adherent cells is that the cells are prone to attaching to the channel surface. To solve this problem, a cross microfluidic chip with three sheath-flow channels located on both sides of and below the sampling channel was developed. With the three sheath flows around the sample solution-containing cells, the formed soft fluid wall prevents the cells from adhering to the channel surface. Labeled cells were 3D hydrodynamically focused by the sheath-flow streams and smoothly introduced into the cross-section one by one. The introduction of sheath-flow streams not only ensured single-cell sampling but avoided blockage of the sampling channel by adherent cells as well. The maximum rate for introduction of individual cells into the separation channel was about 151 cells min−1. With electric field applied on the separation channel, the aligned cells were driven into the separation channel and rapidly lysed within 400 ms at the entry of the channel by sodium dodecylsulfate (SDS) added in the sheath-flow solution. The microfluidic system was evaluated by analysis of reduced glutathione (GSH) and reactive oxygen species (ROS) in single HepG2 cells. The average analysis throughput of ROS and GSH in single cells was 16–18 cells min−1.

A simple but effective subatmospheric pressure device has been developed to drive reagents through microfluidic channels for solution-phase parallel synthesis. Y-shaped microfluidic glass chips with different channel lengths were fabricated using a photolithographic and wet chemical etching procedure. The subatmospheric pressure device, composed of a microvacuum pump, a buffer vessel and a vacuum gauge with two electric switches, can automatically adjust the applied vacuum range in the buffer vessel as required. With the subatmospheric pressure as the driving force, the fluid flow in parallel channels can be precisely controlled, respectively, by the needle valves and monitored by a water filled U-tube manometer. The system was evaluated with Suzuki coupling reaction in a parallel fashion as a demonstration. Experimental results confirmed that the developed system is superior for parallel synthesis parameter evaluation.

This work describes the fabrication of ZrO2/Au nano-composite films and its application for voltammetric detection of organophosphate pesticides. The nano-composite ZrO2/Au film was prepared through a combination of sol–gel procedure and electroless plating that can be carried out in a general chemistry lab with no need for special facilities and reagents. The sensing performance of the ZrO2/Au nano-composite film electrode toward parathion was studied with square wave voltammetry. The nano-ZrO2 showed a strong affinity toward the phosphate group on parathion molecules, which provides sensitivity and selectivity of the sensing film. A linear relationship was obtained between the peak currents and the concentration of parathion, with a detection limit for standard samples of 3 ng/ml. In addition, interference studies showed that structurally similar compounds without phosphate groups would not interfere with the response toward parathion of the film electrode.

Multifunctional upconversion nanoparticles (UCNPs) that can be implemented in theranostic applications are particularly attractive scaffolds for precise drug delivery. However, most of the current methods for drug formulation are technically complicated, thereby impeding their use in the clinic. Here, we report on the preparation of a lipophilic cytotoxic prodrug-integrated and polyethylene glycol (PEG)-cloaked UCNPs scaffold through a facile one-pot supramolecular approach. By choosing 7-ethyl-10-hydroxycamptothecin (SN38)-derived prodrug 1 as a model chemotherapeutic, we show that this lipophilic prodrug can be feasibly self-assembled onto the surface of UCNPs, which are cooperatively solubilized by PEGylated phospholipids. The resulting SN38 prodrug 1-encapsulated UCNPs (designated 1@pUCNPs) produce a stable colloidal system in aqueous solution, making it suitable for intravenous injection. The SN38 drug loading capacity in pUCNPs is as high as ∼12.3 wt%, and a sustained drug release profile is observed, indicating that the drug payloads can be transported to targeted tumor sites via the enhanced permeability and retention (EPR) effect. Upconversion luminescence (UCL) imaging, including in vivo and ex vivo imaging, suggests that the drug-loaded pUCNPs remain stable in tumors over a long time and preferentially accumulate in tumors presumably via the EPR effect. Furthermore, the 1@pUCNPs show superior therapeutic outcomes compared with the clinically approved SN38 prodrug CPT-11 in the Bcap-37 mouse model of breast cancer. Collectively, our results demonstrate that pUCNPs facilely constructed in a one-pot self-assembly manner may be used as a versatile platform, enabling synchronous in vivo delivery of poorly water-soluble drugs and tumor imaging.