Substrate Metabolism-Driven Assembly of High-Quality CdS_xSe_1–x Quantum Dots in Escherichia coli: Molecular Mechanisms and Bioimaging Application

Abstract

Biosynthesis offers opportunities for cost-effective and sustainable production of semiconductor quantum dots (QDs), but is currently restricted by poor controllability on the synthesis process, resulting from limited knowledge on the assembly mechanisms and the lack of effective control strategies. In this work, we provide molecular-level insights into the formation mechanism of biogenic QDs (Bio-QDs) and its connection with the cellular substrate metabolism in Escherichia coli. Strengthening the substrate metabolism for producing more reducing power was found to stimulate the production of several reduced thiol-containing proteins (including glutaredoxin and thioredoxin) that play key roles in Bio-QDs assembly. This effectively diverted the transformation route of the selenium (Se) and cadmium (Cd) metabolic from Cd3(PO4)2 formation to CdS x Se1–x QDs assembly, yielding fine-sized (2.0 ± 0.4 nm), high-quality Bio-QDs with quantum yield (5.2%) and fluorescence lifetime (99.19 ns) far exceeding the existing counterparts. The underlying mechanisms of Bio-QDs crystallization and development were elucidated by density functional theory calculations and molecular dynamics simulation. The resulting Bio-QDs were successfully used for bioimaging of cancer cells and tumor tissue of mice without extra modification. Our work provides fundamental knowledge on the Bio-QDs assembly mechanisms and proposes an effective, facile regulation strategy, which may inspire advances in controlled synthesis and practical applications of Bio-QDs as well as other bionanomaterials.

Single cell electron collectors for highly efficient wiring-up electronic abiotic/biotic interfaces

“…3a ). Among various biomineralized nanoparticles (such as FeS, CdSe, Ag and Pd nanoparticles) 20 , 32 – 34 , FeS nanoparticles were selected for SP collector assembly due to their ease of biosynthesis, high electroactivity and biocompatibility 35 – 37 . To confine the nanoparticles in the periplasm and on the outer membrane surface, a diffusion-confined biosynthesis strategy was developed (Supplementary Fig.…”

Bio‐Metabolism‐Driven Crystalline‐Engineering of CdS Quantum Dots for Highly Active Photocatalytic H2 Evolution

“…It was reported that substrate metabolism regulation greatly affected the fluorescence property of the nanoparticles synthesized by Escherichia coli [6b] . Thus, it is speculated that the crystalline structure of CdS QDs may be controlled by regulating the substrate metabolism of microorganism.…”

Biogenic Sulfur-Based Chalcogenide Nanocrystals: Methods of Fabrication, Mechanistic Aspects, and Bio-Applications

“…Besides, it was hypothesized that glutathione content plays an essential role in the intracellular growth of the NPs [117]. Recently, Tian et al relied on glucose to increase the synthesis rate of CdS x Se 1−x QDs of ~2 nm in size using E. coli JM109 [132]. This effect was attributed to an enhanced synthesis of NADPH and reduced thiol (-SH) groups that directly improved the tolerance to metal toxicity and NP mineralization.…”

“…Besides, the cell viability was monitored every 20 min for 6 h. Neither imaging process nor QDs caused adverse or toxic effects [201]. Lastly, the in vivo bioimaging of MDA-MB-231 breast cancer cell line in mice was performed using fluorescent CdS x Se 1−x QDs synthesized using E. coli [132].…”