CdSe QD Biosynthesis in Yeast Using Tryptone-Enriched Media and Their Conjugation with a Peptide Hecate for Bacterial Detection and Killing

Abstract

The physical and chemical synthesis methods of quantum dots (QDs) are generally unfavorable for biological applications. To overcome this limitation, the development of a novel “green” route to produce highly-fluorescent CdSe QDs constitutes a promising substitute approach. In the present work, CdSe QDs were biosynthesized in yeast Saccharomyces cerevisiae using a novel method, where we showed for the first time that the concentration of tryptone highly affects the synthesis process. The optimum concentration of tryptone was found to be 25 g/L for the highest yield. Different methods were used to optimize the QD extraction from yeast, and the best method was found to be by denaturation at 80 °C along with an ultrasound needle. Multiple physical characterizations including transmission electron microscopy (TEM), dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy (EDX), and spectrophotometry confirmed the optical features size and shape distribution of the QDs. We showed that the novel conjugate of the CdSe QDs and a cell-penetrating peptide (hecate) can detect bacterial cells very efficiently under a fluorescent microscope. The conjugate also showed strong antibacterial activity against vancomycin-resistant Staphylococcus aureus (VRSA), methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia coli, which may help us to cope with the problem of rising antibiotic resistance.

CdSe Quantum Dots in Human Models Derived from ALS Patients: Characterization, Nuclear Penetration Studies and Multiplexing

“…DLS results show that R h values are larger than the geometric radius of the QD conjugates measured by TEM [21] and also confirm the size difference between QD520 and QD655 and the successful bioconjugation of QDs to SpA and antibodies. Differences in the R h between unconjugated QDs, QD-SpA and QD-Ab2 conjugates are in agreement with previously reported results which sustain that the hydrodynamic size of commercial QDs vary substantially in function of the surface functionalization [22][23][24][25].…”

Photocatalytic Decolorization and Biocidal Applications of Nonmetal Doped TiO2: Isotherm, Kinetic Modeling and In Silico Molecular Docking Studies

“…The adhesion between the two surfaces is stronger due to the surface roughness, which in turns stimulate the photocatalyst attachment to bacterial cell thus the photocatalysts penetrates the cell structure and ultimately leads to cell death. These findings are supported by molecular docking studies, where strong evidence of entering TiO 2 into active sites was found that ultimately lead to better photo-biocidal performance [ 62 , 63 , 64 ].…”

Characterization and in vitro Analysis of Probiotic-Derived Peptides Against Multi Drug Resistance Bacterial Infections

“…Dilutions were made and the culture was spread on MH agar plates, which was incubated at 37°C incubator overnight and CFUs were determined the next day. Bacterial culture without PBDM peptides treatment wasere used as negative control and positive control was spread of untreated bacterial culture on agar plates prepared with tetracycline (10 μg/mL) and cefoxitin (32 μg/mL)kanamyicin ( Zhou et al, 2012 ; Haque et al, 2017 ; Sur et al, 2019 ).…”