Lead sulfide quantum dot–serum albumin bioconjugate: spectroscopic, microscopic investigation and photo-conducting current analysis

Abstract

In this article, we focused on the interaction study of chemically fabricated PbS quantum dots (QDs) with model protein bovine serum albumin (BSA). The absorption of the PbS QDs has been observed in the NIR region at λ ≈ 1453 nm with a band gap ≈ 0.91 eV. The average size of the PbS QDs from the HRTEM study was found to be 3.5 nm with well crystalline nature and face-centered cubic (FCC) crystal phase as observed from the XRD study. The ground state complex formation between BSA and PbS QDs at room temperature has been observed and discussed from UV–VIS spectroscopy. The bioconjugate of PbS QDs-BSA formation has been occurring within a colony by the assembly of mesh formation as observed from the HRTEM images. The emission quenching of albumin in the presence of PbS QDs was occurring as observed from the emission spectrum. The energy transfer between serum protein and PbS QDs has been observed. The photo-current within the pure PbS QDs and PbS QDs-BSA conjugate was observed in the nA and µA range, respectively, under photo-conducting process. The albumin corona formation on the PbS QD was accounted for under the four temperatures (T = 300 K, 305 K, 311 K, 316 K) from the dynamic light scattering study.