Aqueous phase one-pot green synthesis of SnSe nanosheets in a protein matrix: negligible cytotoxicity and room temperature emission in the visible region

Abstract

In recent times, SnSe has attracted considerable attention as an environmentally friendly alternative to cadmium-and lead-based photovoltaic materials. Herein, we report a rapid, facile, reproducible, and purely green method for the synthesis of SnSe nanosheets (NS) in an aqueous solution of bovine serum albumin (BSA). Interestingly, BSA itself acted as a reducing agent, stabilizing agent and shape directing template. Time dependent TEM imaging showed the self-assembly of the nanoparticles (NPs) into single crystalline NS. A probable mechanism has been proposed on the basis of the alteration of the intrinsic a-helix structure of BSA into b-pleated sheets at the pH ($3.0) of the reaction mixture. This directs the self-assembly of small SnSe NPs into the NS like structure. It was further evident that the -NH and the -S-S-linkages in the protein are involved in the functionalization of the NPs. As grown SnSe nanomaterial was found to display room temperature photoluminescence (PL), which has been rarely reported. The PL spectra appeared to be the convolution of two bands at 425 and 470 nm, which were attributed to the band-gap and trap/surface state emission, respectively. Moreover, the reduction potential values obtained from the cyclic voltammetry indicate better thermodynamic feasibility for the reduction of SnSe, while the cytotoxicity studies revealed no toxic effects up to a concentration of 100 mM. This signifies the potential application of these nanomaterials in photovoltaics and biomedical contexts.

Can earthworms biosynthesize highly luminescent quantum dots?

“…The strong characteristic bonds observe at 3334.7 cm −1 were attributed to the O − H stretching mode. The band centred at 2931.7 cm −1 corresponding to the N − H stretching vibrations of amide I overlapped with the C − H stretching mode . The band at 1409.…”

“…The band centred at 2931.7 cm −1 corresponding to the N − H stretching vibrations of amide I overlapped with the C − H stretching mode. [29][30][31] The band at 1409. 74 cm −1 was assigned to the symmetrical COO − mode, [32] and N-H bending/C-H stretching vibrations of amide II.…”

“…74 cm −1 was assigned to the symmetrical COO − mode, [32] and N-H bending/C-H stretching vibrations of amide II. [29,30] The other characteristic peak appeared at 1601.7 cm −1 corresponded to C=O stretching vibrations (belonging to amide) and overlapped with the N − H stretching band of the amide I and the peaks centred at 1033 cm −1 were attributed to the C − C stretching band. [29,31] Moreover, the bands at 534 cm −1 and 637 cm −1 could be attributed to the Se − S stretching band and the disulfide stretching vibrations, respectively.…”

“…[29,30] The other characteristic peak appeared at 1601.7 cm −1 corresponded to C=O stretching vibrations (belonging to amide) and overlapped with the N − H stretching band of the amide I and the peaks centred at 1033 cm −1 were attributed to the C − C stretching band. [29,31] Moreover, the bands at 534 cm −1 and 637 cm −1 could be attributed to the Se − S stretching band and the disulfide stretching vibrations, respectively. [29] From the FTIR data can be inferred that a protein compound is attached on the surface of the CdSe QDs.…”

“…[29,31] Moreover, the bands at 534 cm −1 and 637 cm −1 could be attributed to the Se − S stretching band and the disulfide stretching vibrations, respectively. [29] From the FTIR data can be inferred that a protein compound is attached on the surface of the CdSe QDs.…”