A fluorescent sensing platform based on collagen peptides-protected Au/Ag nanoclusters and WS2 for determining collagen triple helix integrity

Intrinsic dual emissive insulin capped Au/Ag nanoclusters as single ratiometric nanoprobe for reversible detection of pH and temperature and cell imaging

pH and temperature are two important characteristics in cells and the environment. These, not only in the well-done regulation of cell functions but also in diagnosis and treatment, have a key role. Protein-protected bimetallic nanoclusters are abundantly used in the building of biosensors. However, insulin-stabilized Au-Ag nanoclusters with dual intrinsic emission have not been investigated yet. In this work, Dual emissive insulin templated Au-Ag nanocluster (Ins(Au/Ag)NCs) were first synthesized in a simple and green one-put manner. The two emission wavelengths of, as-prepared NCs centered at 410 and 630 nm, excited in one excitation wavelength (330 nm). These two emission peaks were assigned to the di-Tyrosine cross-linked formation and bimetallic nanoclusters respectively. Further analysis displayed that each emission band of Ins(Au/Ag)NCs responded to one variable whilst another peak remained constant; For blue and red emission wavelengths, pH dependency and thermo-responsibility were observed respectively. As-prepared nanoprobe with the intrinsic dual emissive feature was used for ratiometric determination of these parameters, each with a discrete response from another. The linear range of 6.0-9.0 for pH and 1 to 71 °C for temperature was obtained, which comprises the physiological range of pH and temperature and afforded intracellular sensing and imaging capability. As-prepared NCs probe show excellent biocompatibility and cell membrane permeability, and so were successfully applied as direct ratiometric pH and temperature probes in HeLa and HFF cells. More interestingly, this dual emissive nanoprobe is capable of distinguishing cancer cells from normal ones.

A fluorescent aptasensor for highly sensitive and selective detection of carcinoembryonic antigen based on upconversion nanoparticles and WS2 nanosheets

A highly sensitive fluorescent aptasensor for carcinoembryonic antigen (CEA) was developed by employing upconversion nanoparticles (UCNPs) as an energy donor and WS2 nanosheets as an energy acceptor, respectively. Polyacrylic acid (PAA) modified NaYF4:Yb/Er UCNPs and an amine modified CEA aptamer were linked together by a covalent bond. Owing to the physical adsorption between WS2 nanosheets and the CEA aptamer, the UCNPs-aptamer was close to WS2 nanosheets, resulting in upconversion fluorescence energy transfer from UCNPs to WS2 nanosheets, and the UCNP fluorescence was quenched. With the introduction of CEA into the UCNPs-aptamer complex system, the aptamer preferentially bound to CEA resulting in a change in spatial conformation which caused UCNPs to depart from WS2 nanosheets. As a result, the energy transfer was inhibited and the fluorescence of UCNPs was observed again, and the degree of fluorescence recovery was linearly related to the concentration of CEA in a range of 0.05-10 ng mL-1 with a limit of detection of 0.008 ng mL-1. Furthermore, the aptasensor based on UCNPs and WS2 nanosheets could be competent for detecting CEA in human serum, which suggests the great application potential of the proposed aptasensor in clinical diagnosis.

Balanced chemical reactivity, antimicrobial properties and biocompatibility of decellularized dermal matrices for wound healing

The prevention of bacterial infection and prompt wound repair are crucial considerations when local skin tissue is compromised by burns, cuts, or similar injuries. Porcine acellular dermal matrix (pADM) is a commonly employed biological material in wound repair due to its inherent natural properties. Nonetheless, the pADM's primary constituent, collagen fibers, lacks antimicrobial properties and is vulnerable to bacterial infection when used in the treatment of incompletely debrided wounds. Meanwhile, conventional antimicrobial agents primarily consist of chemical compounds that exhibit inadequate biocompatibility and biological hazards. This research endeavors to create an antimicrobial collagen scaffold dressing utilizing the Schiff base reaction through the incorporation of oxidized chitosan diquaternary (ODHTCC) salt into the pADM. Compared with the unmodified pADM, ODHTCC-pADM (OD-pA) still retained the three-stranded helical structure of natural collagen. At an ODHTCC cross-linker concentration of 4%, the thermal denaturation temperature of OD-pA was 85 °C. According to the enzymatic degradation resistance test in vitro, the degradation resistance of OD-pA to type I collagenase was significantly improved compared with that of the uncross-linked pADM. In addition, OD-pA exhibited good antibacterial properties, with inhibition rates of 95.6% and 99.9% for E. coli and Staphylococcus aureus, respectively, and a cytotoxicity level 1, meeting the in vitro requirements of national biomedical materials. In vivo experiments showed that the OD-pA scaffold could better promote wound healing and more effectively promote the positive expression of bFGF, PDGF and VEGF. In conclusion, OD-pA has struck a balance between antibacterial properties, chemical reaction properties and biocompatibility, ultimately achieving controllability, and has broad application prospects in the field of antibacterial biomedical materials.