Search

Carcinoembryonic antigen (CEA) is regarded as a promising broad spectrum tumor biomarker for clinical diagnosis, progression, and prognosis. Surface plasmon resonance imaging (SPRi) was considered as one of the powerful tools for immunoassay with advantages of label-free, real-time detection with high-throughput. Herein, wavy gold-silver alloy nanoplates functionalized with anti-CEA antibodies providing high protein loading capacity and high mass are used as signal enhancers for CEA detection through SPRi sandwich assay. The present method exhibits a dynamic range for CEA determination from 0.1 to 312.5 ng mL

Activated carbon (AC) has been widely used in the prevention and control of air and water pollution due to its excellent adsorption ability. However, the adsorption capacity of AC for targeting organic compounds is reduced because of the competitive adsorption of water molecules. The current study proposes hydrophobic modification and regeneration of waste AC as a solution to these issues. Using waste AC as raw material, SiO2 particles were introduced to increase its surface roughness and micropores of AC. Nonpolar alkyl chain groups were grafted on the surface of AC to improve its hydrophobic performance, and high-temperature regeneration was used to increase its specific surface area. The experimental results showed that the water contact angle of AC increased from 30° (hydrophilic) to 142° (hydrophobic) after modification, and it maintained an angle of 139° even after high-temperature regeneration. The specific surface area of hydrophobic AC increased from 290 to 1075 m2 g−1 and the equilibrium adsorption capacity of hydrophobic AC for methylene blue is 425.4 mg g−1 after regeneration. AC-adsorbed methylene blue also has excellent hydrophobicity (145°) and high specific surface area (1250 m2 g−1) after being modified and regenerated by the same methods. After being exposed to air for 600 days, the modified AC still has good hydrophobicity (125°). This indicates that our method of hydrophobic modification combined with regeneration has great significance to the recovery and utilization of waste AC.

Pentraxin-3 (PTX-3) is one of the newly discovered tumor biomarker, especially in the diagnosis of lung cancer. The functionalized multi-walled carbon nanotubes (MWCNTs) and gold nanowires (AuNWs) nanocomposites decorated the PTX-3 biosensor were reported in this work, realizing ultrasensitive detection of PTX-3 in human serum through simple and effective non-enzymatic reaction. The PTX-3 biosensor has excellent electrochemical activity and biocompatibility through carbon and metal nanomaterials. Compared with pure MWCNTs, the MWCNTs combined with AuNWs which shows a wide range of detection (0.001–1000 ng ml-1), higher sensitivity (17.10 μA/(ng ml-1)/cm2) and lower detection limits (0.16 pg ml-1, S/N = 3). Meanwhile, gold nanomaterials are one of the most stable noble metal nanomaterials and MWCNTs possess large electroactive surface area, which can greatly improves the stability (96.3%, after 3 weeks) and repeatability (RSD = 0.51%). This work remarkably extends the utilization of MWCNTs and AuNWs in the construction of biosensors in the fields of biosensing and medical diagnosis.

A simple protease-free and signal-on electrochemical biosensor based on GR-5 DNAzyme and catalytic hairpin assembly (CHA) for sensitive lead ion (Pb2+) assay was constructed in this work. In the presence of Pb2+, GR-5 DNAzyme specifically reacted with Pb2+ and cleaved the substrate strand into two free DNA fragments, and one of the two fragments then opened the hairpin capture DNA (Hc) that was assembled on the Au electrode surface and triggered the CHA reaction. Exploiting the CHA strategy, a large number of the hairpin signal DNA (Hs) labeled with two methylene blues (Mbs) were captured on the Au electrode surface and generated an efficient electron transfer, resulting in the dramatic increase of methylene blue current. In this method, Pb2+ could be detected quantitatively in the range of 4 × 10−11–3 × 10−6 M, and the detection limit was as low as 2.7 × 10−11 M (S/N = 3). Experimental results demonstrated that the biosensor was highly specific for Pb2+ and exhibited remarkable improvements of electrochemical analytical performance. This biosensor was also used for the analysis of Pb2+ in the serum sample spiked with Pb2+, and the obtained result in good agreement with the correct values. The excellent performance of the biosensor shows its promising potential for the clinical diagnosis of lead poisoning.

Single-walled carbon nanotubes (SWCNTs) cannot be stably dispersed in aqueous solutions, which greatly limit their use in biomedical applications. In this study, functionalized SWCNTs were dispersed in chitosan (CS) solution, which greatly promoted the water solubility of SWCNTs and formed a uniformly dispersed solution. The use of EDC/NHS crosslinking solution to activate carboxyl groups into amino groups, greatly improved the affinity of SWCNTs for biomolecules. TEM characterization of the nanocomposites showed that SWCNTs were uniformly dispersed in CS solution. Cyclic voltammetry and electrochemical impedance spectroscopy revealed that the nanocomposites covering the glassy carbon electrode (GCE) greatly improved the conductivity of the electrodes and enhanced the electron transfer rate. A simple electrochemical biosensor for the detection of serum leptin was successfully fabricated with the functionalized-SWCNTs–CS biopolymer nanocomposites on GCEs. The biosensor demonstrated a wide linear range (0–1000 ng mL −1 ) and a detection limit of 5 pg mL −1 (S/N = 3).