ABSTRACT
This study explores a sustainable approach for synthesizing silver nanocomposites (AgNCs) with enhanced antimicrobial and bioactivity using safe Lactobacillus strains and a whey-based medium (WBM). WBM effectively supported the growth of Lactobacillus delbrueckii and Lactobacillus acidophilus, triggering a stress response that led to AgNCs formation. The synthesized AgNCs were characterized using advanced spectroscopic and imaging techniques such as UVâvisible, Fourier transform infrared (FT-IR) spectroscopy, transmission electron (TEM), and scanning electron microscopy with energy dispersive X-ray analysis (SEM-Edx). Lb acidophilus-synthesized AgNCs in WBM (had DLS size average 817.2-974.3 ± PDI = 0.441 nm with an average of metal core size 13.32 ± 3.55 nm) exhibited significant antimicrobial activity against a broad spectrum of pathogens, including bacteria such as Escherichia coli (16.47 ± 2.19 nm), Bacillus cereus (15.31 ± 0.43 nm), Clostridium perfringens (25.95 ± 0.03 mm), Enterococcus faecalis (32.34 ± 0.07 mm), Listeria monocytogenes (23.33 ± 0.05 mm), methicillin-resistant Staphylococcus aureus (MRSA) (13.20 ± 1.76 mm), and filamentous fungi such as Aspergillus brasiliensis (33.46 ± 0.01 mm). In addition, Lb acidophilus-synthesized AgNCs in WBM exhibit remarkable free radical scavenging abilities, suggesting their potential as bioavailable antioxidants. These findings highlight the dual functionality of these biogenic AgNCs, making them promising candidates for applications in both medicine and nutrition.
Subject(s)
Microbial Sensitivity Tests , Nanocomposites , Silver , Whey , Nanocomposites/chemistry , Silver/chemistry , Silver/pharmacology , Whey/chemistry , Whey/metabolism , Lactobacillus acidophilus/drug effects , Lactobacillus acidophilus/metabolism , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/biosynthesis , Metal Nanoparticles/chemistry , Lactobacillus/metabolism , Anti-Infective Agents/pharmacology , Anti-Infective Agents/chemistry , Spectroscopy, Fourier Transform InfraredABSTRACT
The interaction of 2-amino-4,6-dimethyl pyrimidine (ADMP) with beta-cyclodextrin (beta-CD) has been studied by means of UV absorption, steady state and time resolved fluorescence techniques. Spectral characteristics, bandwidths and photophysical parameters indicating that ADMP experience two different environments in aqueous solutions: bulk water and 1:1 (ADMP:beta-CD) inclusion complexation. The size restriction of the upper rim of beta-CD partially include ADMP and prevent the possibility of formation of 1:2 complex. The effective polarity of the cyclodextrin cavity experienced by the induced ADMP is equivalent with the polarity of an 80:20 methanol-water mixture.
Subject(s)
Cyclodextrins/chemistry , Pyrimidines/chemistry , Spectrophotometry/methods , beta-Cyclodextrins , Hydrogen Bonding , Kinetics , Models, Chemical , Models, Molecular , Protein Binding , Temperature , Time Factors , Ultraviolet RaysABSTRACT
The fluorescence decay from S2(pi, pi*) state of 2,5-diphenyl-1,6,6a-trithiapentalene (DP-TTP) in cyclohexane, tetrahydrofuran and acetonitrile solutions of a quantum yield of approximately 0.02-0.04 were measured. The results indicate that, the dominant process of radiationless deactivation of the S2 state, is internal conversion to the S1 state. Upon laser pulse excitation (lambda(ex) = 532 nm) from the S1(pi, pi*) state, DP-TTP in deoxygenated benzonitrile, acetonitrile, ethanol and tetrahydrofuran solutions give rise to transient triplet triplet absorption (lambdaTmax = 700-720 nm). Kinetic data are presented for intrinsic triplet lifetimes, self-quenching and quenching by oxygen.
