A hair-ball heterostructure of MnS-MnS2/CdS with compact linking interface for ultrasensitive photoelectrochemical bioanalysis of carcinoembryonic antigen

Abstract

The heterostructured photoelectric material is supposed to markedly promote the photoelectrochemical (PEC) property. Herein, the species heterostructured MnS/CdS and MnS-MnS2/CdS(1∼2) composites derived from Mn-ZIF MOFs via a sulfofication reaction using Cd(NO3)2, CdC12 cadmium source, respectively. Under irradiation, the PEC tests showed that the photocurrent response of MnS-MnS2/CdS(1∼2) signally enhanced compared to globose MnS/CdS heterostructure and pure MnS or CdS. It was ascribed to the matching band-gap to form type II heterojunction in MnS-MnS2/CdS(1∼2) which dramatically facilitated photo-induced electron/hole (e−/h+) separation and transfer. The hair-ball morphologies structure of MnS-MnS2/CdS(1∼2) with large number of pores was beneficial to improve penetrating efficiency of the electrolyte liquid. Meanwhile, the well-synergistic effect on the MnS, MnS2, CdS components and with tight connecting heterojunction interface among MnS-MnS2/CdS(1∼2) which also led to violently photocurrent output. Besides, the chitosan (CS) was covalently coupled with glutaraldehyde (GLD) to obtain steady composite film, and the cross-linker of GLD can achieve the high efficiency to graft the Apt-CEA (aptamer) biomolecules, which resulting in the promotion of hybridization reaction efficiency of the CEA target. Hence, this created biosensor of Apt-CEA/GLD-CS/MnS-MnS2/CdS(1)/ITO for the CEA detection displayed a wide linear range from 0.001 to 18 ng mL−1 and with ultralow detection limit of 0.313 pg mL−1. This research innovatively prepared a contact heterojunction interface with special porosities structure, which had superior PEC nature for the fabrication of high-performance biosensor.