A colorimetric and photothermal dual-mode chiral sensor based on CuS-L-histidine for optical resolution of aspartic acid isomers.

As the chiral source, L-histidine (L-His) is used for the decoration of copper sulfide nanoparticles (CuS NPs), which is further utilized to fabricate a colorimetric and photothermal dual-mode chiral sensor for the optical resolution of aspartic acid (Asp) isomers. Since the optical activity of L-His is consistent with L-Asp, the CuS-L-His shows higher affinity for L-Asp than D-Asp, and thus more 3,3',5,5'-tetramethylbenzidine (TMB) is captured by CuS-L-His/L-Asp through electrostatic attractions compared with CuS-L-His/D-Asp. Owing to the superior peroxidase-like activity of CuS NPs, the captured TMB can be catalyzed to blue oxidized TMB (oxTMB) in the presence of HO, and thus the optical resolution of the Asp isomers can be realized by the colorimetric mode.

Synthesis of chiral hollow polymer microspheres and their applications in the spectroscopic chiral discrimination of tryptophan isomers.

Hollow polymer microspheres (HPMs) were synthesized, which were then hydrolyzed in aqueous ammonia to produce carboxyl (-COOH) groups on their surface. L-phenylalanine (L-Phe) was grafted to the hydrolyzed HPMs (H-HPMs) through amidation reactions, endowing the H-HPMs with chirality. The resultant chiral HPMs (C-HPMs) were used for the chiral discrimination of tryptophan (Trp) isomers.

A photothermal effect-based chiral sensor for chiral discrimination and sensitive detection.

Chiral analysis with simple devices is of great importance for analytical chemistry. Based on the photothermal (PT) effect, a simple chiral sensor with a portable laser device as the light source and a thermometer as the detection tool was developed for the chiral recognition of tryptophan (Trp) isomers and the sensitive sensing of one isomer (L-Trp). Gold nanorods (GNRs), which have outstanding photo-thermal conversion ability due to their localized surface plasma resonance (LSPR) effect, are used as PT reagents, and biomacromolecules bovine serum albumin (BSA) are used as natural chiral sources, and thus, GNRs@BSA was obtained through Au-S bonds.

An electrochemical sensor based on molecularly imprinted poly(o-phenylenediamine) for the detection of thymol.

A molecularly imprinted electrochemical sensor was facilely fabricated for the detection of thymol (THY). o-Phenylenediamine (oPD) was used as the functional monomer and electropolymerized on the surface of the glassy carbon electrode (GCE) by using THY as the templates. After the THY templates were removed with 50 % (v/v) ethanol, imprinted cavities complementary to the templates were formed within the poly(o-phenylenediamine) (PoPD) films.

A chiral metal-organic framework/cyclodextrin sensing interface for the chiral discrimination of tryptophan enantiomers.

A chiral metal-organic framework (CMOF) was synthesized by introducing L-histidine (L-His) to zeolitic imidazolate framework-8 (ZIF-8) and then grafting with carboxymethyl-β-cyclodextrin (CM-β-CD). Compared with L-His-ZIF-8, the CM-β-CD-functionalized L-His-ZIF-8 (L-His-ZIF-8-CD) showed significantly enhanced discrimination ability for the tryptophan (Trp) enantiomers owing to the inherent chirality of CM-β-CD. The specificity of the chiral interface was also studied, and the results indicated that the discrimination ability for Trp enantiomers is significantly stronger than that for the enantiomers of cysteine (Cys) and tyrosine (Tyr), which might be due to the better matching between the indole ring of Trp and the chiral cavity of CM-β-CD.

Colorimetric discrimination and spectroscopic detection of tyrosine enantiomers based on melamine induced aggregation of l-cysteine/Au nanoparticles.

Au nanoparticles (AuNPs) are decorated by l-cysteine (L-Cys), and the resultant chiral L-Cys/AuNPs can be used for colorimetric discrimination and spectroscopic detection of the tyrosine (Tyr) enantiomers. Melamine (Mel) can induce the aggregation of the L-Cys/AuNPs through ligand exchange, leading to a distinct color change from wine red to purple. Owing to the same rotatory direction of L-Cys/AuNPs and L-Tyr, the L-Cys/AuNPs exhibit a significantly higher binding affinity toward L-Tyr than D-Tyr, and thus the Mel induced aggregation of the L-Cys/AuNPs is greatly alleviated by the protection from the L-Tyr protective layer.

CdSe/ZnS quantum dot-encoded maleic anhydride-grafted PLA microspheres prepared through membrane emulsification for multiplexed immunoassays of tumor markers.

Early diagnosis of tumor markers is of great importance for the successful treatment of cancer. As a high-throughput and high-sensitivity detection technology, liquid suspension biochips based on quantum dot (QD) encoded microspheres have been widely used in the immunodetection of tumor markers. In this work, maleic anhydride grafted PLA (PLA-MA) microspheres based on quantum dot encoding were used as carriers for liquid phase suspension biochips for the immunoassay of tumor markers.

Immunoassay of SARS-CoV-2 nucleocapsid proteins using novel red emission-enhanced carbon dot-based silica spheres.

It is imminent to develop a new type of rapid COVID-19 detection method with high sensitivity. Here, we used novel red emission-enhanced carbon dot (CD)-based silica (RCS) spheres as the signals of lateral flow immunochromatography (LFI) to ultrasensitively detect novel severe acute respiratory syndrome coronavirus 2 nucleocapsid proteins (SARS-CoV-2 NPs). The red emission of CDs can be enhanced and enriched in silica spheres by a simple way.

Luminous silica colloids with carbon dot incorporation for sensitive immunochromatographic assay of Zika virus.

Here a novel strategy is reported of assembling silanized carbon dots (CDs) with porous silica templates to form fluorescent CD-based silica (FCS) colloids with uniformly packed CDs throughout the silica matrix. Dendritic silica spheres with highly accessible central-radial pores are adopted as a powerful absorbent host, which can form Si-O bonds with silane to directly fix the silanized CDs. The appropriate loading content of CDs on the inner surface of dendritic silica spheres is beneficial for the maximum fluorescence intensity of FCS colloids.

Ultrasensitive Detection of Severe Fever with Thrombocytopenia Syndrome Virus Based on Immunofluorescent Carbon Dots/SiO Nanosphere-Based Lateral Flow Assay.

Sensitive detection of severe fever with thrombocytopenia syndrome virus (SFTSV) by a point-of-care assay is of great significance for promoting clinical diagnosis. In this work, ultrasensitive detection of SFTSV was achieved by using fluorescent carbon dots/SiO nanospheres (CSNs) as reporters for a lateral flow assay. The prepared CSNs were resistant to extreme environments and had strong stability.