Antibiotic-Loaded Gold Nanoparticles: A Nano-Arsenal against ESBL Producer-Resistant Pathogens

Making vancomycin a potent broad-spectrum antimicrobial agent using polyaziridine-stabilized gold nanoparticles as a delivery vehicle

The rise of antimicrobial drug resistance among microorganisms presents a global challenge to clinicians. Therefore, it is essential to investigate drug delivery systems to combat resistant bacteria and fungi. This study examined the potential and mode of action of vancomycin-conjugated gold nanoparticles (PEI-AuNP@Van) to enhance vancomycin's biocidal activity against C. tropicalis, C. albicans, E. coli, and P. aeruginosa. Drug conjugation and nanoparticle characterization were assessed using UV-Vis spectroscopy, X-ray diffraction, TEM, ATR-FTIR, and fluorescence spectroscopy. Effective vancomycin conjugation on polyethyleneimine-stabilized gold nanoparticles was achieved via electrostatic interactions or hydrogen bonding between the COO-/OH groups of vancomycin and the NH- groups of polyethyleneimine, yielding nanoparticles with a narrow size distribution and high zeta potential. The high luminescence of the nanoparticles facilitated their detection in microbial cells. PEI-AuNP@Van was internalized in C. albicans and C. tropicalis but showed surface adsorption in E. coli and P. aeruginosa. The in vitro results indicated that the nanodelivery system exhibited superior biocidal activity against the tested strains compared to free vancomycin and unconjugated AuNPs. The mode of action of PEI-AuNP@Van was cell-type-dependent, involving intracellular reactive oxygen species accumulation, cell membrane integrity loss, and apoptosis. The development of antimicrobial nanoformulations using AuNPs and efficient conjugation systems offers a promising approach to address antimicrobial drug resistance.

Sustainable streptomycin-based Ag nanoparticle synthesis and study of the cytotoxicity

Antibiotic resistance is one of the major problems of our time, which can be addressed by the use of different nanoparticles synthesized using antibiotics. The interaction between nanoparticles and biological systems is dynamic, which makes them extremely powerful for applications in the biomedical field. In this work, silver nanoparticles (Ag NPs) were synthesized with streptomycin and characterized by TEM, XRD, and UV-VIS. The synthesis resulted in the formation of spherical particles in the size range of 10-20 nm, which did not show any signs of aggregation after several days, facilitating their ease of use. Cytotoxicity studies of the synthesized AgNPs were performed by flow cytometry on A549 lung cancer cells after 24 h of exposure. At a concentration of 0.02 mM AgNP, the live cell ratio did not differ significantly from the control, but LC50 value was between 1.7 and 1.9 mM. The change in mitochondrial activity was examined after 4 h of exposure, and the results showed that AgNPs synthesized with streptomycin induce a decrease in mitochondrial activity at concentrations as low as 0.01 mM Ag NP. In this study, we have shown that antibiotic-streptomycin-stabilized nanoparticles play a dual role by both reducing and stabilizing silver nanoparticles without the need for any undesirable additive. Nanostructured silver particles synthesized with antibiotics were effective against the cancer cell line used. This is most probable because damage to the mitochondria induces the production of free radicals leading to severe cell damage. The research contributes to a deeper understanding of the effects of nanoparticles on cancer cells. The ability to stabilize silver nanoparticles with antibiotic-loaded nanoparticles could enhance therapeutic efficacy and open new opportunities for the design and development of nanomedicines for use in various biomedical fields such as wound healing, drug delivery, and antimicrobial coatings.

Gold nanoparticles synthesized from soil-derived Streptomyces sp. ASM19: characterization, antimicrobial, anticancer potency targeted G2/M phase cell-cycle arrest, and in silico studies

Gold nanoparticles (Au) have attracted considerable attention in the field of biomedicine in recent years. The present work was designed to investigate gold nanoparticles obtained using a soil-associated actinomycetes, Streptomyces sp. ASM19. This microorganism was isolated and identified using DNA sequencing. The chemical profile of the Streptomyces sp. ASM19 extract was analyzed using LC-HRES-MS. Streptomyces sp. ASM19 extract was utilized to synthesize actinomycetes-based gold nanoparticles (Ac-AuNPs), which were analyzed using ultraviolet-visible (UV-vis) spectrophotometry, Fourier transform infrared (FTIR) spectroscopy, and atomic force microscopy (AFM). In addition, the antibacterial, and anti-biofilm, as well as, the anti-proliferative properties of Ac-AuNPs against seven cancer lines were investigated. LC-HRES-MS analysis traced a total of 111 peaks, 14 of them are key peaks belonging to the chemical classes, alkaloids, steroids, and polyketides. Analysis of the synthesized Ac-AuNPs revealed that they exhibited a wine-red color and a plasmon band appeared at 540 nm, confirming the formation of the Ac-AuNPs. Further, FTIR confirmed various functional groups present in Ac-AuNPs. The crude extract of Streptomyces sp. ASM19 demonstrated consistent antibacterial activity in contrast to Ac-AuNPs. The anti-proliferative properties of Ac-AuNPs demonstrated encouraging anticancer properties against SCC9 and SCC25 cell lines with IC50 values of 3.77 and 1.56 μg mL-1. Furthermore, Ac-AuNPs had total apoptotic percentages of 26.37% (SCC9) and 32.08% (SCC25), which are around 25 times higher than the control (0.95%). Additionally, it caused a notable G2/M phase cell-cycle arrest. On the other hand, molecular docking study carried out for the annotated compounds; tomaymycin (8) and nocapyrone P (5), showed considerable binding affinities compared to the co-crystallized inhibitor (fisetin) against the cyclin-dependent kinase 6 active site. Overall, the present study could be useful for nano drug delivery and may be applied for clinical studies in the future.

Spinorphin Molecules as Opportunities for Incorporation into Spinorphin@AuNPs Conjugate Systems for Potential Sustained Targeted Delivery to the Brain

Background: This study explores the potential for the synthesis of peptide nanosystems comprising spinorphin molecules (with rhodamine moiety: Rh-S, Rh-S5, and Rh-S6) conjugated with nanoparticles (AuNPs), specifically peptide Rh-S@AuNPs, peptide Rh-S5@AuNPs, and peptide Rh-S6@AuNPs, alongside a comparative analysis of the biological activities of free and conjugated peptides. The examination of the microstructural characteristics of the obtained peptide systems and their physicochemical properties constitutes a key focus of this study. Methods: Zeta (ζ) potential, Fourier transformation infrared (FTIR) spectroscopy, circular dichroism (CD), scanning electron microscopy (SEM-EDS), transmission electron microscopy (TEM), and UV-Vis spectrophotometry were employed to elucidate the structure-activity correlations of the peptide@nano AuNP systems. Results: The zeta potential values for all the Rh-S@AuNPs demonstrate that the samples are electrically stable and resistant to flocculation and coagulation. The absorption of energy quanta from UV-Vis radiation by the novel nanopeptide systems does not substantially influence the distinctive signal of AuNPs, which is situated at around 531 nm. The FTIR measurements indicate the signals associated with the unique functional groups of the peptides, whereas circular dichroism verifies the synthesis of the conjugated nanocomposites of the spinorphin@AuNP type. An analysis of the SEM and TEM data revealed that most AuNPs have a spherical morphology, with an average diameter of around 21.92 ± 6.89 nm. The results of the in vivo studies showed promising findings regarding the anticonvulsant properties of the nanocompounds, especially the Rh-S@AuNP formulation. Conclusions: All the nanocompounds tested demonstrated the ability to reduce generalized tonic-clonic seizures. This suggests that these formulations may effectively target the underlying neuronal hyperexcitability. In addition, the prepared Rh-S@AuNP formulations also showed anticonvulsant activity in the maximal electroshock test performed in mice, which was evident after systemic (intraperitoneal) administration. The study's findings indicate that conjugates can be synthesized via a straightforward process, rendering them potential therapeutic agents with biological activity.

Streptomyces monashensis MSK03-mediated synthesis of gold nanoparticles: characterization and antibacterial activity

Nanotechnology is a cutting-edge field with diverse applications, particularly in the utilization of gold nanoparticles (AuNPs) due to their stability and biocompatibility. AuNPs serve as pivotal components in medical applications, with a specific emphasis on their significant antibacterial efficacy. This study focuses on synthesizing AuNPs using the cell-free supernatant of Streptomyces monashensis MSK03, isolated from terrestrial soil in Thailand. The biosynthesis process involved utilizing the cell-free supernatant of S. monashensis MSK03 and hydrogen tetrachloroauric acid (HAuCl4) under controlled conditions of 37 °C and 200 rpm agitation. Characterization studies revealed spherical AuNPs with sizes ranging from 7.1 to 40.0 nm (average size: 23.2 ± 10.7 nm), as confirmed by TEM. UV-Vis spectroscopy indicated a localized surface plasmon resonance (LSPR) band at 545 nm, while XRD analysis confirmed a crystalline structure with characteristics of cubic lattice surfaces. The capping molecules on the surface of AuNPs carry a negative charge, indicated by a Zeta potential of -26.35 mV, and FTIR analysis identified functional groups involved in reduction and stabilization. XANES spectra further confirmed the successful reduction of Au3+ to Au0. Moreover, the synthesized AuNPs demonstrated antibacterial activity against drug-resistant strains of Pseudomonas aeruginosa and Acinetobacter baumannii. Interestingly, the AuNPs showed non-toxicity to Vero cell lines. These significant antibacterial properties of the produced nanoparticles mean they hold great promise as new antimicrobial treatments for tackling the increasing issue of antibiotic resistance.

Recent Advances in the Development of Antibiotics-Coated Gold Nanoparticles to Combat Antimicrobial Resistance

Antimicrobial resistance (AMR) has become an alarming threat to the successful treatment of rapidly growing bacterial infections due to the abuse and misuse of antibiotics. Traditional antibiotics bear many limitations, including restricted bioavailability, inadequate penetration and the emergence of antimicrobial-resistant microorganisms. Recent advances in nanotechnology for the introduction of nanoparticles with fascinating physicochemical characteristics have been predicted as an innovative means of defence against antimicrobial-resistant diseases. The use of nanoparticles provides several benefits, including improved tissue targeting, better solubility, improved stability, enhanced epithelial permeability and causes minimal side effects. However, except for gold nanoparticles (AuNPs), the biological safety of the majority of metal nanoparticles remains a serious problem. AuNPs appear to be promising for drug delivery and medicinal applications because of their minimal toxicity, biocompatibility, functional flexibility, chemical stability and versatile biological activities, such as their antiviral, antifungal, anti-inflammatory and antimicrobial properties. Hence, we are focusing on the gold nanoparticles possessing antimicrobial activity in this article. This review will cover recent strategies in the preparation of gold nanoparticles, with special emphasis placed on antibiotics-coated AuNPs with enhanced antimicrobial properties and how they fight against disease-causing bacteria and eradicate biofilms, along with their activities and physicochemical properties.

An Overview of Stimuli-Responsive Intelligent Antibacterial Nanomaterials

Drug-resistant bacteria and infectious diseases associated with biofilms pose a significant global health threat. The integration and advancement of nanotechnology in antibacterial research offer a promising avenue to combat bacterial resistance. Nanomaterials possess numerous advantages, such as customizable designs, adjustable shapes and sizes, and the ability to synergistically utilize multiple active components, allowing for precise targeting based on specific microenvironmental variations. They serve as a promising alternative to antibiotics with diverse medical applications. Here, we discuss the formation of bacterial resistance and antibacterial strategies, and focuses on utilizing the distinctive physicochemical properties of nanomaterials to achieve inherent antibacterial effects by investigating the mechanisms of bacterial resistance. Additionally, we discuss the advancements in developing intelligent nanoscale antibacterial agents that exhibit responsiveness to both endogenous and exogenous responsive stimuli. These nanomaterials hold potential for enhanced antibacterial efficacy by utilizing stimuli such as pH, temperature, light, or ultrasound. Finally, we provide a comprehensive outlook on the existing challenges and future clinical prospects, offering valuable insights for the development of safer and more effective antibacterial nanomaterials.

Nano-Formulating Besifloxacin and Employing Quercetin as a Synergizer to Enhance the Potency of Besifloxacin against Pathogenic Bacterial Strains: A Nano-Synergistic Approach

The present study applied a nano-synergistic approach to enhance besifloxacin's potency via nano-formulating besifloxacin on gold nanoparticles (Besi-AuNPs) and adding quercetin as a natural synergistic compound. In fact, a one-pot AuNP synthesis approach was applied for the generation of Besi-AuNPs, where besifloxacin itself acted as a reducing and capping agent. Characterization of Besi-AuNPs was performed by spectrophotometry, DLS, FTIR, and electron microscopy techniques. Moreover, antibacterial assessment of pure besifloxacin, Besi-AuNPs, and their combinations with quercetin were performed on Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. UV-spectra showed a peak of AuNPs at 526 nm, and the electron microscopy-based size was estimated to be 15 ± 3 nm. The effective MIC₅₀ concentrations of besifloxacin after loading on AuNPs were reduced by approximately 50% against the tested bacterial strains. Interestingly, adding quercetin to Besi-AuNPs further enhanced their antibacterial potency, and isobologram analysis showed synergistic potential (combination index below 1) for different quercetin and Besi-AuNP combinations. However, Besi-AuNPs and quercetin combinations were most effective against Gram-positive S. aureus in comparison to Gram-negative P. aeruginosa and E. coli. Their potent activity against S. aureus has its own clinical significance, as it is one the main causative agents of ocular infection, and besifloxacin is primarily used for treating infectious eye diseases. Thus, the outcomes of the present study could be explored further to provide better medication for eye infections caused by resistant pathogens.