A high-throughput photo-electrochromic ratiometric sensing chip for swine enteric coronaviruses detection

Porcine deltacoronavirus (PDCoV), porcine epidemic diarrhea virus (PEDV), and porcine transmissible gastroenteritis virus (TGEV) are the main swine enteric coronaviruses, which pose significant threats to the swine industry due to their highly contagious nature and the severe clinical symptoms they cause in pigs. In this research, a high-throughput photo-electrochromic (EC) ratiometric sensing chip was developed for simultaneous detection of PEDV, PDCoV and TGEV. The sensing chip consists of three detection channels and one reference channel fabricated by laser etching. Three-dimensional nitrogen-doped graphene nanosheet-loaded ZnIn₂S₄ (ZnIn₂S₄/3DNG) as the photoelectrochemical active materials and antibodies for PEDV, PDCoV and TGEV as immuno-recognition probes were modified on the electron-injection (EI) areas. Prussian Blue (PB) as an electrochromic material is modified on the EC areas. The photogenerated electrons by ZnIn₂S₄/3DNG can induce the color change of PB under light illumination. The capture of viruses by their antibodies can hinder the electron transfer and affect the speed of electrochromism. Therefore, based on the ratio of the grayscale values of EC areas in three detection channels and one reference channel, the simultaneous detection of PEDV, PDCoV and TGEV can be achieved in the range of 1.0 × 10² TCID 50⋅mL^-1 to 1.0 × 10⁵ TCID 50⋅mL^-1, 5.0 × 10³ TCID 50⋅mL^-1 to 1.0 × 10⁷ TCID 50⋅mL^-1, and 1.0 × 10³ TCID 50⋅mL^-1 to 1.0 × 10^7.5 TCID 50⋅mL^-1, respectively. The sensing chip provides an efficient, portable detection platform for swine enteric coronaviruses.