One-pot wet-chemical fabrication of 3D urchin-like core-shell Au@PdCu nanocrystals for electrochemical breast cancer immunoassay.

Carbohydrate antigen 15-3 (CA15-3) is an important biomarker for early diagnosis of breast cancer. Herein, a label-free electrochemical immunosensor was built based on three-dimensional (3D) urchin-like core-shell Au@PdCu nanocrystals (labeled Au@PdCu NCs) for highly sensitive detection of CA15-3, where K3[Fe(CN)6] behaved as an electroactive probe. The Au@PdCu NCs were synthesized by a simple one-pot wet-chemical approach and the morphology, structures, and electrocatalytic property were investigated by several techniques. The Au@PdCu NCs prepared worked as electrode material to anchor more antibodies and as signal magnification material by virtue of its exceptional catalytic property. The developed biosensor exhibited a wide linear detection range from 0.1 to 300 U mL-1 and a low limit of detection (0.011 U mL-1, S/N = 3) for determination of CA15-3 under the optimal conditions. The established biosensing platform exhibits some insights for detecting other tumor biomarkers in clinical assays and early diagnosis.

Bimetallic AuPt alloy/rod-like CeO2 nanojunctions with high peroxidase-like activity for colorimetric sensing of organophosphorus pesticides.

Organophosphorus pesticides (OP) have extensive applications in agriculture, while their overuse causes inevitable residues in food, soil, and water, ultimately being harmful to human health and even causing diverse dysfunctions. Herein, a novel colorimetric platform was established for quantitative determination of malathion based on peroxidase mimic AuPt alloy decorated on CeO2 nanorods (CeO2@AuPt NRs). The synthesized nanozyme oxidized colorless 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2. Besides, the oxidized TMB was inversely reduced by ascorbic acid (AA), which were originated from hydrolysis of L-ascorbic acid-2-phosphate (AA2P) with the assistance of acid phosphatase (ACP). Based upon this observation ACP analysis was explored by colorimetry, showing a wid linear range of 0.2 ~ 3.5 U L-1 and a low limit of detection (LOD = 0.085 U L-1, S/N = 3). Furthermore, malathion present in the colorimetric system inhibited the activity of ACP and simultaneously affected the generation of AA, in turn promoting the recovery of the chromogenic reaction. Based on this, the LOD was decreased to 1.5 nM (S/N = 3) for the assay of malathion with a wide linear range of 6 ~ 100 nM. This simple colorimetric platform provides some informative guidelines for determination of other pesticides and disease markers.

Dual II-scheme nanosheet-like Bi2S3/Bi2O3/Ag2S heterostructures for ultrasensitive PEC aptasensing of aflatoxin B1 coupled with catalytic signal amplification by dendritic nanorod-like Au@Pd@Pt nanozyme.

As one of the most toxic chemical substances, aflatoxin B1 (AFB1) has a strong carcinogenic effect even at a trace level in human and animal, which severely threatens human health and even causes cancers. Therefore, ultrasensitive detection of AFB1 is of significant importance. For such analysis, dual II-scheme sheet-like Bi2S3/Bi2O3/Ag2S heterostructures were prepared by the in-situ growth method, which exhibited high separation efficiency for the electron-hole (e--h+) pairs, prominent stability, and high photoactivity. Moreover, the dendritic nanorod-like Au@Pd@Pt (Au@Pd@Pt DNRs) nanozyme was homely synthesized, whose peroxidase-like activity was scrupulously investigated by catalytical oxidation of diaminobenzidine (DAB) in the presence of H2O2. Integration by the aptasensing strategy, a photoelectrochemical (PEC) "signal-on" aptasensor was prepared, which exhibited a broader linear range of 0.5 pg mL-1-100 ng mL-1 with a lower limit of detection (LOD = 0.09 pg mL-1, S/N = 3). This work provides a feasible strategy to develop advanced PEC biosensors for actual analysis of environmental pollutants.

Electrochemical label-free immunoassay of HE4 using 3D PtNi nanocubes assemblies as biosensing interfaces.

Human epididymis protein 4 (HE4) is a vital biomarker for early diagnosis of epithelial ovarian cancer (EOC). Herein, a new label-free biosensor was developed using K3[Fe(CN)6] as the electrochemical probe for ultrasensitive immunoassay of HE4 based on PtNi nanocubes assemblies (NCAs) as efficient biosensing interfaces. The PtNi NCAs were synthesized by a simple solvothermal approach, where N-hexadecyltrimethylammonium chloride (HTAC) and 2,2'-bis(4,5-dimethylimidazole) (BDMM) behaved as co-structuring directors. Under the optimal conditions, the obtained HE4 immunosensor displayed a wide detection range from 0.001 to 100 ng mL-1 and a low detection limit (0.11 pg mL-1, S/N = 3). As a result, the current sensing platform would serve as a useful reference for detecting cancer biomarkers in the clinical assay and diagnosis.

Ultrasensitive label-free electrochemical immunosensor of NT-proBNP biomarker based on branched AuPd nanocrystals/N-doped honeycombed porous carbon.

N-terminal pro-B-type natriuretic peptide is a major cardiac biomarker for early diagnosis and prognosis of heart failure. Herein, a novel label-free electrochemical immunosensor was developed based on home-made branched AuPd nanocrystals/N-doped porous carbon (AuPd NCS/NPC) for ultrasensitive and high-selective detection of N-terminal pro-B-type natriuretic peptide. Specifically, the AuPd NCS/NPC was prepared by a one-pot wet-chemical strategy by using thymine as a green structural directing agent, whose morphology, structures, and properties were strictly examined, showing high-efficiency catalysis towards electro-reduction of hydrogen peroxide. Under the optimized conditions, the fabricated sensor exhibited a dynamic linear range of 0.001 âˆ¼ 10 ng mL-1 and a low limit of detection (0.34 pg mL-1, S/N = 3) for immunoassay of N-terminal pro-B-type natriuretic peptide. Furthermore, this platform was explored for detection of the biomarker in human serum sample with satisfactory results. Thus, the built biosensor can render valuable guidance for prospective clinical diagnostic applications.

A sandwich-type electrochemical immunosensor for CYFRA 21-1 based on probe-confined in PtPd/polydopamine/hollow carbon spheres coupled with dendritic Au@Rh nanocrystals.

A signal-on sandwich-like electrochemical immunosensor was built for determination of cytokeratin 19 fragments 21-1 (CYFRA 21-1) in non-small cell lung cancer (NSCLC) by confining electroactive dye (e.g., methylene blue, MB) as a probe for amplifying signals. Specifically, core-shell gold@rhodium dendritic nanocrystals (Au@Rh DNCs) behaved as a substrate for primary antibody and accelerate interfacial electron transfer. Besides, hollow carbon spheres (HCSs) were subsequently modified with polydopamine (PDA) and PtPd nanoparticles for sequential integration of the secondary antibody and confinement of MB as a label, termed as MB/PtPd/PDA/HCSs for clarity. The built sensors showed a broad linear range (100 fg mL-1 ~ 100 ng mL-1) for detection of CYFRA 21-1 with an ultra-low detection limit (31.72 fg mL-1, S/N = 3), coupled with satisfactory performance in human serum samples. This work can be explored for assays of other proteins and provides some constructive insights for early and accurate diagnosis of NSCLC.