Electrochemical impedimetric immunosensor based on stabilized lipid bilayer-tethered WS2@MWCNT for the sensitive detection of carcinoembryonic antigen.

An innovative and ultrasensitive electrochemical impedimetric immunosensor was developed for the quantitative detection towards carcinoembryonic antigen (CEA). CEA is a widely utilized tumour biomarker that is generated in a wide variety of cancers and it is a frequently used biomarker for clinical research and early detection of cancer. Novelty of the present work is the utilization of biomimetic membrane comprising gold nanoparticle-stabilized lipid bilayer (SLB) containing DOPE (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine) and DOTAP (N-[1-(2,3-Dioleoyloxy)propyl]-N,N,N-trimethyl ammonium Propane) for easy protein insertion, bio-affinity, and bio-functionalization towards the detection of CEA. The SLB is tethered on stable tungsten disulfide decorated MWCNT (WS2@MWCNT) surface for the sensitive and selective detection of CEA. The WS2@MWCNT surface has been chosen to tether SLB due to its numerous unique characteristics such as greater surface area, high conductivity, and excellent electronic conductivity, which in turn leads to the improvement of the superior electrochemical sensing ability towards CEA. The lone SLB when used for protein insertion lacks space and impedes the functional incorporation of transmembrane proteins with hydrophilic domains on both sides and biosensing applications. The SLB-tethered WS2@MWCNT surface (SLB-WS2@MWCNT) was examined by studying the electrochemical changes in the existence of redox probe K3/K4 [Fe(CN)6] through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The combined excellent properties of WS2@MWCNT and SLB have shown to amplify the sensitive detection of CEA with a LOD value of 0.2 pg mL-1. The developed sensor provides higher stability, sensitivity, and excellent reproducibility towards the detection of CEA with relative standard deviation (RSD) of < 5%. The encouraging results demonstrate that the CEA impedimetric immunosensor has potential in practical analysis and lays a solid platform for additional biomarker detection in early clinical diagnosis.

1-Benzyl-4',5'-diphenyl-piperidine-3-spiro-3'-pyrrolidine-2'-spiro-3''-indoline-4,2''-dione.

The asymmetric unit of the title compound, C(34)H(31)N(3)O(2), consists of two independent mol-ecules which differ slightly in the orientations of the phenyl rings with respect to the pyrrolidine ring. In both mol-ecules, the piperidin-4-one ring adopts a chair conformation, whereas the pyrrolidine ring adopts an envelope conformation in one of the mol-ecules and a twisted conformation in the other. An intra-molecular C-H⋯O hydrogen bond is observed. The crystal packing is stabilized by inter-molecular N-H⋯O hydrogen bonds and C-H⋯π inter-actions.