Loading Nanoceria Improves Extracellular Vesicle Membrane Integrity and Therapy to Wounds in Aged Mice.

Wound healing is a programmed process through which tissue restores its integrity after an injury. Advancing age is a risk factor for delayed cutaneous wound healing; however, ideal therapeutic approaches for aged wound have not been developed yet. By dissecting the harsh microenvironment of aged wound, we propose an integrated chemical and biological strategy to mitigate two main hostile factors including oxidative stress and ischemia. Mesenchymal stem cell-derived extracellular vesicles (EVs) are a rising star in regenerative medicine due to their powerful facilitation in tissue repair and regeneration. However, the fragile lipid membrane limits their function under the oxidative stress microenvironment. Nanoceria is an antioxidative nanozyme; here, we reveal that nanoceria-loaded EVs derived from mesenchymal stem cells facilitate cutaneous wound healing in aged mice. DG-CeO2 was prepared via coating CeO2 covalently with d-glucose to promote their cellular endocytosis. DG-CeO2 was packaged into EVs under optimized hypoxic conditions (DG-CeO2 EVsHyp). We further demonstrated that DG-CeO2 EVsHyp had favorable biocompatibility and antioxidative and proangiogenic effects during the cutaneous wound healing in both young and aged mice. Further evidence revealed that DG-CeO2 EVsHyp-transferred miR-92a-3p/125b-5p and their targets associated with aging degeneration may be the potential mechanisms. Collectively, these findings highlight that nanoceria-loaded EVs released by engineered stem cells may represent a potential therapeutic approach for tissue regeneration in aged population.

A two-wavelength fluorescence recovery method for the simultaneous determination of aureomycin and oxytetracycline by using gold nanocrystals modified with serine and 11-mercaptoundecanoic acid.

A method is described for rapid (1 h) synthesis of gold nanoclusters (AuNCs) co-functionalized with serine and 11-mercaptoundecanoic acid. The co-functionalized AuNCs exhibit good stability towards temperature, pH values, and over time. They were characterized by atomic force microscopy, high-resolution transmission electron microscopy, dynamic light scattering, and by fluorescence, IR and X-ray photoelectron spectroscopies. The fluorescence of the AuNCs is quenched by Hg(II) and restored on subsequent addition of aureomycin (CTC) or oxytetracycline (OTC). A fluorescent turn-on assay was worked out for simultaneous detection of CTC and OTC based on recording the change of the restored fluorescence measured at 420 and 500 nm under 340 nm photoexcitation. The detection limits are 20 and 9 nM for CTC and OTC, respectively. The concentrations of CTC and OTC can also be visualized by UV illumination. The nanoprobe was successfully applied to the simultaneous determination of CTC and OTC in spiked human urine. Graphical abstract Schematic of a two-wavelength fluorescence recovery method for the simultaneous determination of aureomycin and oxytetracycline. It is based on the use of gold nanocrystals modified with serine and 11-mercaptoundecanoic acid, and on recording the change of the restored fluorescence measured at 420 and 500 nm.

Aptamer induced multicoloured Au NCs-MoS2 "switch on" fluorescence resonance energy transfer biosensor for dual color simultaneous detection of multiple tumor markers by single wavelength excitation.

An aptamer induced "switch on" fluorescence resonance energy transfer (FRET) biosensor for the simultaneous detection of multiple tumor markers (e.g., AFP and CEA) combining molybdenum disulfide (MoS2) nanosheets with multicolored Au NCs by a single excitation was developed for the first time. Here, AFP aptamer functionalized green colored Au NCs (510 nm) and CEA aptamer functionalized red colored Au NCs (650 nm) are used as energy donors, while MoS2 is used as energy receptor. On the basis of recording the change of the recovered fluorescence intensity at 510 nm and 650 nm upon the addition of targets CEA and AFP, these two tumor markers can be simultaneously quantitatively detected, with detection limits of 0.16 and 0.21 ng mL-1 (3σ) for AFP and CEA, respectively. In addition, it is noteworthy that the developed biosensor can not only realize accurate quantitative determination of multiple tumor markers by fluorescent intensity, but also be applied in semi-quantitative determination through photo visualization. More importantly, confocal microscope experiments prove that serums from normal and hepatoma patients can also be visually and qualitatively discriminated by this FRET-based biosensor with a single excitation wavelength, indicating promising potential of this assay for clinical diagnosis.

Near infrared fluorescent dual ligand functionalized Au NCs based multidimensional sensor array for pattern recognition of multiple proteins and serum discrimination.

Here, a multidimensional sensor array capable of analyzing various proteins and discriminating between serums from different stages of breast cancer patients were developed based on six kinds of near infrared fluorescent dual ligand functionalized Au NCs (functionalized with different amino acids) as sensing receptors. These six kinds of different amino acids functionalized Au NCs were synthesized for the first time within 2h due to the direct donation of delocalized electrons of electron-rich atoms or groups of the ligands to the Au core. Based on this, ten proteins could be simultaneously and effectively discriminated by this "chemical nose/tongue" sensor array. Linear discrimination analysis (LDA) of the response patterns showed successful differentiation of the analytes at concentrations as low as 10nM with high identification accuracy. Isothermal titration calorimetry (ITC) experiment illustrates that Au NCs interacted with proteins mainly by hydrogen bonding and van der Waals forces. Furthermore, the greatest highlight of this sensor array is demonstrated by successfully discriminating between serums from different stages of breast cancer patients (early, middle and late) and healthy people, suggesting great potential for auxiliary diagnosis.

A novel dual-functional biosensor for fluorometric detection of inorganic pyrophosphate and pyrophosphatase activity based on globulin stabilized gold nanoclusters.

A novel ultrasensitive dual-functional biosensor for highly sensitive detection of inorganic pyrophosphate (PPi) and pyrophosphatase (PPase) activity was developed based on the fluorescent variation of globulin protected gold nanoclusters (Glo@Au NCs) with the assistance of Cu2+. Glo@Au NCs and PPi were used as the fluorescent indicator and substrate for PPase activity evaluation, respectively. In the presence of Cu2+, the fluorescence of the Glo@Au NCs will be quenched owing to the formation of Cu2+-Glo@Au NCs complex, while PPi can restore the fluorescence of the Cu2+-Glo@Au NCs complex because of its higher binding affinity with Cu2+. As PPase can catalyze the hydrolysis of PPi, it will lead to the release of Cu2+ and re-quench the fluorescence of the Glo@Au NCs. Based on this mechanism, quantitative evaluation of the PPi and PPase activity can be achieved ranging from 0.05 µM to 218.125 µM for PPi and from 0.1 to 8 mU for PPase, with detection limits of 0.02 µM and 0.04 mU, respectively, which is much lower than that of other PPi and PPase assay methods. More importantly, this ultrasensitive dual-functional biosensor can also be successfully applied to evaluate the PPase activity in human serum, showing great promise for practical diagnostic applications.

Dual ligand co-functionalized fluorescent gold nanoclusters for the "turn on" sensing of glutathione in tumor cells.

In this work, we develop a facile one-step strategy for rapidly preparing dual ligand co-functionalized fluorescent gold nanoclusters (Au NCs) and establish a "turn on" approach for the rapid and selective sensing of glutathione (GSH) in aqueous solution and living cells. The as-prepared Au NCs exhibited orange red fluorescence (λem = 608 nm), a long lifetime (5.62 µs), a large stokes shift (>300 nm), and considerable stability and were systematically characterized by using fluorescence spectroscopy, high-resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS), fluorescence lifetime, infrared (IR) spectroscopy and ultraviolet absorption spectroscopy. Based on the fluorescence recovery induced by competitive coordination with Cu2+ between Au NCs and GSH, the present "turn on" approach offers a high sensitivity and excellent selectivity toward GSH detection with a detection limit of 9.7 nM. More importantly, this "turn on" approach could also be successfully applied for visualizing and monitoring the changes in the intracellular GSH level in Hep G2 cells, providing available potential for diagnostic applications.

Novel dual ligand co-functionalized fluorescent gold nanoclusters as a versatile probe for sensitive analysis of Hg(2+) and oxytetracycline.

In this work, we present a direct one-step strategy for rapidly preparing dual ligand co-functionalized fluorescent Au nanoclusters (NCs) by using threonine (Thr) and 11-mercaptoundecanoic acid (MUA) as assorted reductants and capping agents in aqueous solution at room temperature. Fluorescence spectra, high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and infrared (IR) spectroscopy were performed to demonstrate the optical properties and chemical composition of the as-prepared AuNCs. They possess many attractive features such as near-infrared emission (λem = 606 nm), a large Stoke's shift (>300 nm), high colloidal stability (pH, temperature, salt, and time stability), and water dispersibility. Subsequently, the as-prepared AuNCs were used as a versatile probe for "turn off" sensing of Hg(2+) based on aggregation-induced fluorescence quenching and for "turn-on" sensing of oxytetracycline (OTC). This assay provided good linearity ranging from 37.5 to 3750 nM for Hg(2+) and from 0.375 to 12.5 µM for OTC, with detection limits of 8.6 nM and 0.15 µM, respectively. Moreover, the practical application of this assay was further validated by detecting OTC in human serum samples.

Ultrasensitive photoelectrochemical immunoassay of antibody against tumor-associated carbohydrate antigen amplified by functionalized graphene derivates and enzymatic biocatalytic precipitation.

Tumor-associated carbohydrate antigens (TACAs) are often found on the surface of cancer cells. The determination of the carbohydrate components of glycoconjugates is challenging because of the chemical complexity of glycan chains. Through monitoring corresponding antibody, we can get a good solution for clinical diagnosis. Here breast tumor-associated carbohydrate antigens Tn were used as a model and a new photoelectrochemical biosensor for ultrasensitive detection of antibody against Tn was developed. To enhance the sensitivity, both graphene oxide and graphene were used during the construction of biosensor. Through the formation of immunocomplex and the insoluble biocatalytic precipitation (BCP) product, photocurrent intensity was decreased greatly and the antibody could be detected from 0.5 to 500 pg/mL with a detection limit of 1.0×10(-13) g/mL. At the same time, the developed biosensor showed acceptable selectivity and could be used in the complex matrix. Compared with the traditional glycoarray method, this PEC method is more sensitive (5 orders of magnitude), and thus provides another platform to monitor the immune response to carbohydrate epitopes at different stages during differentiation, metastasis, or treatment.

Proximity-dependent isothermal cycle amplification for small-molecule detection based on surface enhanced Raman scattering.

A novel proximity-dependent isothermal cycle amplification (PDICA) strategy has been proposed and successfully used for the determination of cocaine coupled with surface enhanced Raman scattering (SERS). For enhancing the SERS signal, Raman dye molecules modified bio-barcode DNA and gold nanoparticles (AuNPs) are used to prepare the Raman probes. Magnetic beads (MBs) are used as the carrier of amplification template and signal output products for circumventing the problem of high background induced by excess bio-barcode DNA. In the presence of target molecules, two label-free proximity probes can hybridize with each other and subsequently opens the hairpin connector-probe to perform the PDICA reaction including the target recycling amplification and strand-displacement amplification. As a result, abundant AuNPs Raman probes can be anchored on the surface of MBs and a low detection limit of 0.1 nM for cocaine is obtained. This assay also exhibits an excellent selectivity and has been successfully performed in human serum, which confirms the reliability and practicality of this protocol.

A sensitive quartz crystal microbalance assay of adenosine triphosphate via DNAzyme-activated and aptamer-based target-triggering circular amplification.

In this work, a simple and novel quartz crystal microbalance (QCM) assay is demonstrated to selectively and sensitively detect the adenosine triphosphate (ATP). The amplification process consists of circular nucleic acid strand-displacement polymerization, aptamer recognition strategy and nanoparticle signal amplification. With the involvement of an aptamer-based complex, two amplification reaction templates and AuNP-functionalized probes, the whole circle amplification process is triggered by the target recognition of ATP. As an efficient mass amplifier, AuNP-functionalized probes are introduced to enhance the QCM signals. As a result of DNA multiple amplification, a large number of AuNP-functionalized probes are released and hybridized with the capture probes on the gold electrode. Therefore the QCM signals are significantly enhanced, reaching a detection limit of ATP as low as 1.3 nM. This strategy can be conveniently used for any aptamer-target binding events with other biological detection such as protein and small molecules. Moreover, the practical determination of ATP in cancer cells demonstrates the feasibility of this QCM approach and potential application in clinical diagnostics.