Accurate determination of intracellular glucose is very important for exploring its chemical and biological functions in metabolism events of living cells. In this paper, we developed a new noninvasive and highly selective nanokit for intracellular glucose monitoring via two-step recognition. The liposome-based nanokit coencapsulated the aptamer-functionalized gold nanoparticles (AuNPs) and the Shinkai’s receptor together. When the proposed nanokit was transfected into living cells, the Shinkai’s receptor could recognize glucose first and then changed its conformation to endow aptamers with binding and sensing properties which were not readily accessible otherwise. Then, the binary complexes formed by the intracellular glucose and the Shinkai’s receptor can in situ displace the complementary oligonucleotide of the aptamer on the surface of AuNPs. The fluorophore-labeled aptamer was away from the AuNPs, and the fluorescent state switched from “off” to “on”. Through the secondary identification of aptamer, the selectivity of the Shinkai’s receptor could be greatly improved while the intracellular glucose level was assessed by fluorescence signal recovery of aptamer. In the follow-up application, the approach exhibits excellent selectivity and is noninvasive for intracellular glucose monitoring under normoxia and hypoxia. To the best of our knowledge, this is the first time that the advantages of organic receptors and nucleic acids have been combined and highly selective monitoring of intracellular glucose has been realized via two-step recognition. We expect it to open up new possibilities to integrate devices for diagnosis of various metabolic diseases and insulin delivery.

Herein, we demonstrated a new gold nanoparticles (AuNPs)-integrated programmable triple-helix molecular switch (THMS) to realize the biosensing of multiple targets from in homogenous solution to in living cells. The results demonstrated that this proposed programmable THMS could be successfully used for imaging multiple messenger RNA (mRNA) in living cells and it significantly extends the scope of the THMS sensing platform.

The levels of circulating tumor DNA (ctDNA) in the peripheral blood have been associated with tumor burden and malignant progression. However, ultrasensitive detection of ctDNA in blood remains to be explored. Herein, we have developed a new approach, employing DNA-mediated surface-enhanced Raman scattering (SERS) of single-walled carbon nanotubes (SWNTs), that allows ultrasensitive detection of a broad range of ctDNAs in human blood. Combined with the efficient ctDNA recognition capacity of our designed triple-helix molecular switch and RNase HII enzyme-assisted amplification, the T-rich DNA-mediated SERS enhancement of SWNTs could read out a content of KRAS G12DM as low as 0.3 fM, with a detection of 5.0 μL of sample volume, which has potential for point-of-care testing in clinical analysis.

In this communication, we propose a gold nanorod-based SERS nanotracker to monitor the local pH change during photothermal therapy (PTT). The dynamic SERS analysis indicated that the local pH of the lysosome in living cells increased during the PTT which would be helpful to understand the cellular metabolic processes and further facilitate the photosensitizer screening and optimization.

Hypoxia is considered to contribute to pathophysiology in various cells and tissues, and a clear understanding about the relationship between hypoxia and intracellular acidification will help to elucidate the complex mechanism of glycolysis under hypoxia. However, current studies are mainly focused on overexpression of intracellular reductases accelerated by hypoxia, and the investigations focusing on the relationship between hypoxic degree and intracellular acidification remain to be explored. For this vacuity, we report herein a new activatable nanoprobe for sensing pH change under different degrees of hypoxia by surface-enhanced Raman spectroscopy (SERS). The monitoring was based on the SERS spectra changes of 4-nitrothiophenol (4-NTP)-functionalized gold nanorods (AuNR@4-NTP) resulting from the nitroreductase (NTR)-triggered reduction under hypoxic conditions while the as-generated 4-aminothiophenol (4-ATP) is a pH-sensitive molecule. This unique property can ensure the SERS monitoring of intracellular acidification in living cells and tissues under hypoxic conditions. Dynamic pH analysis indicated that the pH decreased from 7.1 to 6.5 as a function of different degrees of hypoxia (from 15 to 1%) due to excessive glycolytic activity triggered by hypoxia. Given the known advantages of SERS sensing, these findings hold promise in studies of pathophysiological pathways involving hypoxia.

•This work developed a quadratic SERS signal amplified method for telomerase activity detection.•This method is PCR-free and enzyme-free.•The limit of detection was calculated to be as low as single cell.•It is capable of distinguishing cancer cell from a vast majority of normal cells.•This method allowed the sensing of telomerase activity from cancer tissues.As an important biomarker and therapeutic target, telomerase has attracted extensive attention concerning its detection and monitoring. Recently, enzyme-assisted amplification approaches have provided useful platforms for the telomerase activity detection, however, further improvement in sensitivity is still hindered by the single-step signal amplification. Herein, we develop a quadratic signal amplification strategy for ultrasensitive surface-enhanced Raman scattering (SERS) detection of telomerase activity. The central idea of our design is using telomerase-induced silver nanoparticles (AgNPs) assembly and silver ions (Ag+)-mediated cascade amplification. In our approach, each telomerase-aided DNA sequence extension could trigger the formation of a long double-stranded DNA (dsDNA), making numerous AgNPs assembling along with this long strand through specific Ag–S bond, to form a primary amplification element. For secondary amplification, each conjugated AgNP was dissolved into Ag+, which can effectively induce the 4-aminobenzenethiol (4-ABT) modified gold nanoparticles (AuNPs@4-ABT) to undergo aggregation to form numerous “hot-spots”. Through quadratic amplifications, a limit of detection down to single HeLa cell was achieved. More importantly, this method demonstrated good performance when applied to tissues from colon cancer patients, which exhibits great potential in the practical application of telomerase-based cancer diagnosis in early stages. To demonstrate the potential in screening the telomerase inhibitors and telomerase-targeted drugs, the proposed design is successfully employed to measure the inhibition of telomerase activity by 3’-azido-3’-deoxythymidine.

Multifunctional nanoparticles integrated with an imaging module and therapeutic drugs are promising candidates for future cancer diagnosis and therapy. Mesoporous silica coated gold nanorods (AuNR@MS) have emerged as a novel multifunctional cancer theranostic platform combining the large specific surface area of mesoporous silica, which guarantees a high drug payload, and the photothermal modality of AuNRs. However, premature release and side effects of exogenous stimulus still hinder the further application of AuNR@MS. To address these issues, herein, we proposed a glutathione (GSH)-responsive multifunctional AuNR@MS nanocarrier with in situ formed silver nanoparticles (AgNPs) as the capping agent. The inner AuNR core functions as a hyperthermia agent, while the outer mesoporous silica shell exhibits the potential to allow a high drug payload, thus posing itself as an effective drug carrier. With the incorporation of targeting aptamers, the constructed nanocarriers show drug release in accordance with an intracellular GSH level with maximum drug release into tumors and minimum systemic release in the blood. Meanwhile, the photothermal effect of the AuNRs upon application to near-infrared (NIR) light led to a rapid rise in the local temperature, resulting in an enhanced cell cytotoxicity. Such a versatile theranostic system as AuNR@MS@AgNPs is expected to have a wide biomedical application and may be particularly useful for cancer therapy.Keywords: gold nanorods; GSH; mesoporous silica nanoparticles; photodynamic therapy; photothermal therapy; silver nanoparticle

One main source of cyanide (CN–) exposure for mammals is through the plant consumption, and thus, sensitive and selective CN– detection in plants tissue is a significant and urgent work. Although various fluorescence probes have been reported for CN– in water and mammalian cells, the detection of endogenous biological CN– in plant tissue remains to be explored due to the high background signal and large thickness of plant tissue that hamper the effective application of traditional one-photo excitation. To address these issues, we developed a new two-photo excitation (TPE) nanosensor using graphene quantum dots (GQDs)/gold nanoparticle (AuNPs) conjugate for sensing and imaging endogenous biological CN–. With the benefit of the high quenching efficiency of AuNPs and excellent two-photon properties of GQDs, our sensing system can achieve a low detection limit of 0.52 μM and deeper penetration depth (about 400 μm) without interference from background signals of a complex biological environment, thus realizing sensing and imaging of CN– in different types of plant tissues and even monitoring CN– removal in food processing. To the best of our knowledge, this is the first time for fluorescent sensing and imaging of CN– in plant tissues. Moreover, our design also provides a new model scheme for the development of two-photon fluorescent nanomaterial, which is expected to hold great potential for food processing and safety testing.Keywords: cyanide; gold nanoparticle; graphene quantum dot; imaging; plant tissue; two-photon

Herein, we proposed a new electrochemical sensing strategy for T2DM-related SNP detection via DNA-mediated growth of AgNPs on a SWCNT-modified electrode. Coupled with RNase HII enzyme assisted amplification, this approach could realize T2DM-related SNP assay and be applied in crude extracts of carcinoma pancreatic β-cell lines.

On the basis of the phenomenon that ATP can induce the formation and increase the catalytic activity of the G-quadruplex, an activatable hairpin DNA probe, which includes the HRP-mimicking G-quadruplex, was designed and utilized for low-background and high-selective colorimetric detection of ATP.

Herein, we proposed a new electrochemical sensing strategy for T2DM-related SNP detection via DNA-mediated growth of AgNPs on a SWCNT-modified electrode. Coupled with RNase HII enzyme assisted amplification, this approach could realize T2DM-related SNP assay and be applied in crude extracts of carcinoma pancreatic β-cell lines.

Herein, we demonstrated a new gold nanoparticles (AuNPs)-integrated programmable triple-helix molecular switch (THMS) to realize the biosensing of multiple targets from in homogenous solution to in living cells. The results demonstrated that this proposed programmable THMS could be successfully used for imaging multiple messenger RNA (mRNA) in living cells and it significantly extends the scope of the THMS sensing platform.

On the basis of the phenomenon that ATP can induce the formation and increase the catalytic activity of the G-quadruplex, an activatable hairpin DNA probe, which includes the HRP-mimicking G-quadruplex, was designed and utilized for low-background and high-selective colorimetric detection of ATP.