Poly(ionic liquid)s-Based Thermal-Responsive Microgel for Use as SERS Substrates with "ON-OFF" Switchable Effect.

A temperature-responsive surface-enhanced Raman scattering (SERS) substrate with "ON-OFF" switching based on poly(ionic liquid)s (PILs) block copolymer microgels have been designed and synthesized. The PIL units act as a joint component to anchor the gold nanoparticles (AuNPs) and analytes onto poly(N-isopropylacrylamide) (PNIPAm). This anchor allows the analytes to be fixed at the formed hot spots under temperature stimulus. Owing to the regulation of the PNIPAm segment, the SERS substrates exhibit excellent thermally responsive SERS activity with a reversible "ON-OFF" effect. Additionally, because of the anion exchange of PILs, microgels can introduce new analytes, which offers more flexibility for the system. The substrate shows excellent reversibility, controllability, and flexibility of SERS activity, which is expected to have a broad application in the field of practical SERS sensors.

Surface-enhanced Raman scattering spectroscopy monitoring and degradation of organic pollutants using a novel nanowire.

A multifunctional Ag/AlOOH nanowires (ANW) composite substrate was constructed, which not only accomplishes highly sensitive detection of organic dye molecules, but also has excellent performance in the degradation of pollutants. The ANW in the Ag/ANW substrate possesses a high aspect ratio, which extends the distribution area of Ag and enables a large number of hot spots on the active substrate. Additionally, due to the abundant OH groups on the ANW, there is an increased number of anchor sites for adsorbed metal ions in the Ag/ANW compound, thus contributing to the enhancement and degradation of molecules. Moreover, the constructed multifunctional Ag/ANW nanocomplexes also show great promise for practical applications, providing a reference for the detection and degradation of contaminants.

Difunctional AuNPs@PVP with oxidase-like activity for SERRS detection of total antioxidant capacity.

Assessing the total antioxidant capacity (TAC) of foods plays a significant role in dietary guidance and disease risk reduction. Therefore, building a simple, rapid, and sensitive sensing method for detecting TAC possesses broad application prospects. Herein, we constructed a novel nanozyme catalyzed‒surface-enhanced Raman resonance scattering (SERRS) sensing strategy for analysis of TAC based on polyvinylpyrrolidone coated gold nanoparticles (AuNPs@PVP) that was synthesized by one step reduction method. AuNPs@PVP not only served as the SERRS substrate but also possessed high oxidase activity which can catalyze 3,3',5,5'-tetramethylbenzidine (TMB) oxidation by generating hydroxyl radicals (•OH) and superoxide anion free radical (•O2-). According to the inhibiting effect of antioxidants, ascorbic acid (AA) was selected as the representative for TAC detection. The linear range and limit of detection (LOD) were determined to be 10-8‒10-5 M and 0.6 nM, respectively. More importantly, the proposed nanozyme catalyzed‒SERRS strategy has been successfully applied to the detection of TAC in fruit juices, demonstrating promising potential in the field of food supervision and healthcare applications.

High SERS performance of functionalized carbon dots in the detection of dye contaminants.

INTRODUCTION: The long-term overuse of malachite green (MG) has potential carcinogenic, teratogenic, and mutagenic effects. The functional nanocomposite is novel and challenging to construct and implement through surface enhanced Raman scattering (SERS) strategy to reveal the contributions in application. OBJECTIVES: The novel Ag-CDs (carbon dots)-PBA (phenyl boric acid) nanocomposite was constructed by a facile route to detect toxic MG molecule with high SERS sensitivity and good uniformity. METHODS: The enhanced substrate used for the detection of MG has been successfully constructed using PBA modulated Ag-CDs on a structured surface with rich binding sites. RESULTS: The fabricated Ag-CDs-PBA substrate can be used to analyze various probe molecules exhibiting high sensitivity, good signal reproducibility, and excellent stability. The mechanism between components has been proved by calculations originating from the plasmonic Ag and active electronic transmission among the bridging CDs and PBA via the close spatial π-π effect. In addition, the accelerated separation of electron-hole pairs was triggered to further improve the SERS activity of the hybrid via a bidirectional charge transfer (CT) process. Significantly, the Ag-CDs-PBA system shows distinctive selectivity, in which PBA can hinder the interference of other species without specific hydroxyl groups. CONCLUSION: Based on this deeper insight on plasmon-mediated mechanism, the SERS substrate was successfully practiced for quantitative determination in real water and fish samples. The strategy developed promises to be a new sensor technology and has great potential for environmental and food safety applications.

Silver-nanoparticle-coated Fe3O4/chitosan core-shell microspheres for rapid and ultrasensitive detection of thiram using surface magnetic solid-phase extraction-surface-enhanced Raman scattering (SMSPE-SERS).

We report a surface magnetic solid-phase extraction-surface-enhanced Raman scattering (SMSPE-SERS) method based on silver-nanoparticle-coated Fe3O4/chitosan (Fe3O4/CS@Ag) microspheres as the substrate, and this method integrates all steps from sample pretreatment to detection. Fe3O4/CS was synthesized by a one-step solvothermal method in which chitosan (CS) was used as a surface modifier and adsorbent. Fe3O4/CS@Ag microspheres exhibit both adsorption ability and SERS activity. Therefore, we used the SMSPE-SERS method to detect pesticide residues on fruit peel. The procedures of capturing, separating and enriching pesticides, as well as detection, are all integrated. In addition, the SERS substrate allows label-free detection of thiram pesticide in both fruit peel and apple juice. Owing to the uniform distribution of Ag NPs and the adsorption ability of CS, the thiram-detection sensitivity was sufficiently high to detect the lowest concentration of 1.2 ng/cm2, which was significantly lower than the maximum thiram residue limit (7 µg/cm2) in fruits. The method was comparable to high-performance liquid chromatography with recovery ranging from 86.60 to 109.69 %.

Dual detection and quantification of hypochlorite and sulfite ions via SERS spectroscopy by utilizing the redox reaction of tetramethylbenzidine.

We developed a highly efficient, ultra-sensitive, and selective dual detection sensor for hypochlorite (ClO-) and sulfite (SO32-) ions based on surface-enhanced Raman scattering (SERS) spectroscopy. 3,3',5,5'-Tetramethylbenzidine (TMB) is oxidized by ClO- under acidic conditions to diazotized oxTMB that, when electrostatically adsorbed onto Au nanoparticles (NPs), produces a strong Raman signal at 1605 cm-1. Meanwhile, oxTMB is reduced to TMB by SO32-, which significantly reduces the Raman signal. The linear detection range of the proposed sensor is 10-10 to 10-6 M with a detection limit of 59 pM for ClO- and 10-9 to 10-5 M with a detection limit of 5.4 nM for SO32-. In addition, the sensor was successfully applied to detect ClO- and SO32- in water samples.

Sensitive SERS assay for L-cysteine based on functionalized silver nanoparticles.

L-cysteine, an indispensable amino acid present in natural proteins, plays pivotal roles in various biological processes. Consequently, precise and selective monitoring of its concentrations is imperative. Herein, we propose a Surface-enhanced Raman Scattering (SERS) sensor for detecting L-cysteine based on the anti-aggregation of 4-mercaptobenzoic acid (4-MBA) and histidine (His) functionalized silver nanoparticles (Ag NPs). The presence of Hg2+ ions can induce the aggregation of Ag NPs@His@4-MBA due to the unique nanostructures of Ag NPs@His@4-MBA, resulting in a robust SERS intensity of 4-MBA. However, in the presence of L-cysteine, the stronger affinity between L-cysteine and Hg2+ reduces the concentration of free Hg2+, causing the dispersion of the aggregated functionalized Ag NPs and the reduction of the SERS signal intensity of 4-MBA. The developed SERS platform demonstrates excellent performance with a low detection limit of 5 nM (S/N = 3) and linear detection capabilities within the range of 0.01-100 µM for L-cysteine. Additionally, the method was successfully employed for the determination of L-cysteine in spiked serum samples, yielding recoveries ranging from 95.0 % to 108.1 % with relative standard deviations of less than 3.3 %. This study not only presents a novel approach for fabricating highly sensitive and specific SERS biosensors for biomolecule detection but also offers a significant strategy for the development and construction of SERS substrates using anti-aggregation design.

Identification of receptors and factors associated with human coronaviruses in the oral cavity using single-cell RNA sequencing.

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) ravaged the world, and Coronavirus Disease 2019 (COVID-19) exhibited highly prevalent oral symptoms that had significantly impacted the lives of affected patients. However, the involvement of four human coronavirus (HCoVs), namely SARS-CoV-2, SARS-CoV, MERS-CoV, and HCoV-229E, in oral cavity infections remained poorly understood. We integrated single-cell RNA sequencing (scRNA-seq) data of seven human oral tissues through consistent normalization procedure, including minor salivary gland (MSG), parotid gland (PG), tongue, gingiva, buccal, periodontium and pulp. The Seurat, scDblFinder, Harmony, SingleR, Ucell and scCancer packages were comprehensively used for analysis. We identified specific cell clusters and generated expression profiles of SARS-CoV-2 and coronavirus-associated receptors and factors (SCARFs) in seven oral regions, providing direction for predicting the tropism of four HCoVs for oral tissues, as well as for dental clinical treatment. Based on our analysis, it appears that various SCARFs, including ACE2, ASGR1, KREMEN1, DPP4, ANPEP, CD209, CLEC4G/M, TMPRSS family proteins (including TMPRSS2, TMPRSS4, and TMPRSS11A), and FURIN, are expressed at low levels in the oral cavity. Conversely, BSG, CTSB, and CTSL exhibit enrichment in oral tissues. Our study also demonstrates widespread expression of restriction factors, particularly IFITM1-3 and LY6E, in oral cells. Additionally, some replication, assembly, and trafficking factors appear to exhibit broad oral tissues expression patterns. Overall, the oral cavity could potentially serve as a high-risk site for SARS-CoV-2 infection, while displaying a comparatively lower degree of susceptibility towards other HCoVs (including SARS-CoV, MERS-CoV and HCoV-229E). Specifically, MSG, tongue, and gingiva represent potential sites of vulnerability for four HCoVs infection, with the MSG exhibiting a particularly high susceptibility. However, the expression patterns of SCARFs in other oral sites demonstrate relatively intricate and may only be specifically associated with SARS-CoV-2 infection. Our study sheds light on the mechanisms of HCoVs infection in the oral cavity as well as gains insight into the characteristics and distribution of possible HCoVs target cells in oral tissues, providing potential therapeutic targets for HCoVs infection in the oral cavity.

Genetic sequence characteristics of varicella-zoster virus epidemic strains in Changchun City from 2021 to 2022 / 中国生物制品学杂志

@#Objective To identify the genotypes and analyze the molecular characteristics of varicella-zoster virus(VZV)endemic strains in Changchun from 2021 to 2022.Methods A total of 59 patients with varicella or herpes zoster treated in China Japan Union Hospital of Jilin University in Changchun from 2021 to 2022 were selected as the research objects,which were identified for the serum VZV-specific antibodies by fluorescent antibody to membrane antigen(FAMA)method.The viral DNA was extracted from herpetic fluid of the confirmed patients,and multiple open reading frames(ORFs)including ORF1,ORF12,ORF16,ORF17,ORF21,ORF22,ORF37,and ORF54 of VZV were amplified by PCR,which was genotyped according to the single nucleotide polymorphisms(SNPs) of the ORFs.Furthermore,multiple ORFs,ORF38,ORF54 and ORF62 were identified by using restriction fragment length polymorphism(RFLP)to distinguish clinical strains and vaccine strains.Results 59 serum samples were positive,indicating that all the patients were infected with VZV.Among the 59 clinical samples,4 samples were completely matched with Clade 2 genotype,4 samples showed 2 SNPs,including ORF1(SNP790)mutation of C→A and ORF12(SNP18 082)mutation of T→C,and 51 samples showed ORF12(SNP18 082)mutation of T→C.All 59 VZV clinical isolates were PstⅠ+BglⅠ+BglⅠ+SmaⅠ+SmaⅠ-,which was different from the vaccine strain PstⅠ-,which was different from the vaccine strain PstⅠ-BglⅠ-BglⅠ+SmaⅠ+SmaⅠ+.Conclusion All the VZV endemic strains in Changchun from 2021 to 2022 were Clade 2 genotype,and no vaccine strain was found to be pathogenic.