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Graphical abstract Highlights • 5 layers of chondroitin 6-sulfate with heparin were bond on the coronary stents. • It prolongs blood clotting time and inhibits platelet adhesion. • It would be beneficial to inhibit smooth-muscle cells growing to avoid restenosis. Abstract To solve the thrombosis and restenosis problem in cardiovascular stent implantation for cardiovascular artery disease, chondroitin 6-sulfate (ChS) with heparin (HEP) have been used as drug carrier layers and alternatively covalently bonded on gold (Au)-dimercaptosuccinic acid (DMSA)-thiolized cardiovascular metallic (SUS316 L stainless steel, SS) stents. Sirolimus, a model drug, was encapsulated in the ChS-HEP alternative layers. The behavior of the drug in releasing and suppressing the growth of smooth-muscle cells (SMCs) was evaluated with 5-layer CHS-HEP coating on the SS stents. Moreover, hemocompatibility of blood clotting time and platelet adhesion was performed. The results showed that the 5-layer ChS-HEP-modified SS stents displayed the greatest hemocompatibility, showing prolonged blood clotting time of the activated partial thrombin time (> 500 s) and less platelet adhesion to reduce thrombosis. Furthermore, sirolimus can be released continuously for more than 40 days with the 5-layer ChS-HEP coating and is beneficial for inhibiting the growth of SMCs; however, it does not affect the proliferation of endothelial cells, which can avoid restenosis formation. Therefore, the multilayers of ChS-HEP grafted onto the Au-DMSA-cardiovascular SS stents provide high potential for use as drug eluting stents. [ABSTRACT FROM AUTHOR]

Nanocomposite materials of the Au nanoparticles (Au/PDDA-G) and the bimetallic PtAu nanoparticles on poly-(diallyldimethylammonium chloride) (PDDA)-modified graphene sheets (PtAu/PDDA-G) were prepared with hydrothermal method at 90 °C for 24 h. The composite materials Au/PDDA-G and PtAu/PDDA-G were evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) for exploring the structural characterization for the electrochemical catalysis. According to TEM results, the diameter of Au and bimetallic PtAu nanoparticles is about 20-50 and 5-10 nm, respectively. X-ray diffraction (XRD) results indicate that both of PtAu and Au nanoparticles exhibit the crystalline plane of (111), (200), (210), and (311). Furthermore, XRD data also show the 2°-3° difference between pristine graphene sheets and the PDDA-modified graphene sheets. For the catalytic activity tests of Au/PDDA-G and PtAu/PDDA-G, the mixture of 0.5 M aqueous HSO and 0.5 M aqueous formic acid was used as model to evaluate the electrochemical characterizations. The catalytic activities of the novel bimetallic PtAu/graphene electrocatalyst would be anticipated to be superior to the previous electrocatalyst of the cubic Pt/graphene. [ABSTRACT FROM AUTHOR]

Gold nanoparticles bound with inositol hexaphosphate (IP6) (AuNPs/IP6) were prepared by in situ reduction of various concentrations of IP6 (0~320 µM) through modified Frens method for surface-enhanced Raman scattering (SERS) detection. The resultant AuNPs/IP6 were subject to characterization including UV/Vis spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential, and X-ray photoelectron spectroscopy (XPS). The results showed that AuNPs with 65 µM of IP6 would result in a core AuNPs-shell (IP6 layer) structure, which exhibited the strongest SERS signal, due to the “hot spot effect” generated from the 1-2 nm interparticle gaps of AuNPs/IP6 nanohybrids (ionic interaction of IP6 and Au+). Furthermore, the reaction kinetics of Au and IP6 were also investigated in this work. Higher concentration of IP6 (190 and 260 µM) will make AuNPs become irregularly shaped, because IP6 is a basic salt and served as a pH mediator. The morphology and distribution of AuNPs were greatly improved by addition of 65 µM of IP6. This novel AuNPs/IP6 nanohybrid showed great stability and Raman enhancement. It is promising in the application of rapid and label-free biological detection of bacteria or tumor cells. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman spectroscopy (SERS) provides a fast, simple, and label-free approach that can directly detect various analytes attached to SERS substrates and provide qualitative and quantitative information based on the SERS spectra of the analyte. The signal enhancement provided by noble metal particles allows us to achieve high sensitivity and good stability even at low concentrations in water quality testing. Over the past decade, SERS has become increasingly popular in the detection field, highlighting its significant application potential. However, the signal enhancement of single AuNPs is inferior to that of AgNPs, but we can achieve an overall enhancement by uniformly arranging multiple AuNPs. The hot-spot effect, which is crucial for Raman signal enhancement, occurs only when NMNPs are within a specific distance. However, when noble metal particles come into contact with each other, the enhancement effect of the hot spot disappears. Therefore, in this study, AuNPs@MPS-SH substrates with surface-enhanced Raman scattering (SERS) activity were successfully synthesized by immobilizing AuNPs on thiol-functionalized mesoporous silica (MPS-SH). MPS nanospheres with tailored pore size and surface-bound -SH groups were synthesized for the controlled embedding of Au nanoparticles (AuNPs). By adjusting the ratio of reactants, uniform AuNP dispersion and strong MPS-AuNP interactions were achieved. This optimized structure creates localized surface plasmon resonance (LSPR) hotspots, significantly enhancing the surface-enhanced Raman scattering (SERS) effect for ultrasensitive analyte detection. Transmission electron microscopy (TEM) revealed that the average diameter of MPS nanoparticles is 260 nm, with a pore size of 8 nm. Optimal Raman enhancement was achieved at an AuNPs concentration of 2.6 × 1018 particles/mL. The lowest detection limit concentration for Rhodamine 6G was below 10−6 M, while for uremic toxin (urea) it was below 10−3 M. The ability to directly detect low concentrations by mixing with the analyte demonstrates the ultra-high sensitivity and label-free detection potential of this study in the fields of water quality and disease detection. • AuNPs@MPS-SH substrates synthesized for enhanced Raman scattering. • Precise pore control & uniform AuNP dispersion boost SERS signal. • MPTMS functionalization enables uniform AuNP attachment within & on MPS pores. • Ultra-sensitive label-free detection achieved with rhodamine 6G below 10−6 M. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermosensitive SERS nanocapsules were developed by AuNPs and Pluronic F127. • 1/8 vol shrinkage of SERS nanocapsules from 15 °C (swelling) to 37 °C (shrinkage). • SERS intensity increase above LCST due to interparticle gap of AuNPs decrease. Thermo-responsive Raman-enhanced nanocapsules were successfully fabricated by Pluronic® F127 (F127) decorated with gold nanoparticles (AuNPs) for surface-enhanced Raman scattering (SERS) detection of biomolecules. F127 nanocapsules changes from hydrophilicity (swelling) to hydrophobicity (de-swelling) when the temperature increases from 15 °C to 37 °C, owing to the lower critical solution temperature (LCST) of F127 is about 26.5 °C. The size of nanocapsules would be enormous shrinking from 160 nm to 20 nm, resulting in a significant decrease in the distance between AuNPs to enhance hot spot effect, which increases the sensitivity of SERS detection. Based on the thermo-sensitive behavior, the ratio of AuNPs and F127 would be manipulated to find the optimal SERS enhancement effect. SERS nanocapsules can rapidly detect biomolecules (adenine and R6G) with limit of detection (LOD) lower than 10−6 M. In addition, the relatively difficult to detect clinical samples, carboxyl-terminal parathyroid hormone fragments (C-PTH), can also be measured by the thermo-responsive SERS nanocapsules developed in this work. It is expected the biomolecules can be adsorbed at low temperature (15 °C), as well as collected and concentrated at high temperature (37 °C) for SERS detection, to increase the sensitivity and stability of SERS detection. [ABSTRACT FROM AUTHOR]