Synthesis, characterization of penicillin G capped silver nanoconjugates to combat β-lactamase resistance in infectious microorganism

Role of Gut Microbiome in Autism Spectrum Disorder and Its Therapeutic Regulation

Autism spectrum disorder (ASD) is a neurological disorder that affects normal brain development. The recent finding of the microbiota–gut–brain axis indicates the bidirectional connection between our gut and brain, demonstrating that gut microbiota can influence many neurological disorders such as autism. Most autistic patients suffer from gastrointestinal (GI) symptoms. Many studies have shown that early colonization, mode of delivery, and antibiotic usage significantly affect the gut microbiome and the onset of autism. Microbial fermentation of plant-based fiber can produce different types of short-chain fatty acid (SCFA) that may have a beneficial or detrimental effect on the gut and neurological development of autistic patients. Several comprehensive studies of the gut microbiome and microbiota–gut–brain axis help to understand the mechanism that leads to the onset of neurological disorders and find possible treatments for autism. This review integrates the findings of recent years on the gut microbiota and ASD association, mainly focusing on the characterization of specific microbiota that leads to ASD and addressing potential therapeutic interventions to restore a healthy balance of gut microbiome composition that can treat autism-associated symptoms.

Recent developments in biomolecule-based nanoencapsulation systems for antimicrobial delivery and biofilm disruption

Biomolecules are very attractive nanomaterial components, generally, due to their biocompatibility, biodegradability, abundance, renewability, and sustainability, as compared to other resources for nanoparticle-based delivery systems. Biomolecule-based nanoencapsulation and nanodelivery systems can be designed and engineered for antimicrobial cargos in order to surmount classical and current challenges, including the emergence of multi-drug resistant strains of microorganisms, the low effectiveness and limitations in the applicability of the present antimicrobials, and biofilm formation. This feature article highlights the recent applications and capabilities of biomacromolecule-based nanomaterials for the delivery and activity enhancement of antimicrobials, and disruption of biofilms. Unique properties of some nanomaterials, arising from specific biomacromolecules, were also emphasized. We expect that this review will be helpful to researchers in engineering new types of antimicrobial nanocarriers, hybrid particles and colloidal systems with tailored properties.

Activating a Silver Lipoate Nanocluster with a Penicillin Backbone Induces a Synergistic Effect against S. aureus Biofilm

Many antibiotic resistances to penicillin have been reported, making them obsolete against multiresistant bacteria. Because penicillins act by inhibiting cell wall production while silver particles disrupt the cell wall directly, a synergetic effect is anticipated when both modes of action are incorporated into a chimera cluster. To test this hypothesis, the lipoate ligands (LA) of a silver cluster (Ag29) of known composition (Ag29LA12)[3-] were covalently conjugated to 6-aminopenicillanic acid, a molecule with a β-lactam backbone. Indeed, the partially conjugated cluster inhibited an Staphylococcus aureus biofilm, in a dose-response manner, with a half-maximal inhibitory concentration IC50 of 2.3 μM, an improvement over 60 times relative to the unconjugated cluster (IC50 = 140 μM). An enhancement of several orders of magnitude over 6-APA alone (unconjugated) was calculated (IC50 = 10 000 μM). Cell wall damage is documented via scanning electron microscopy. A synergistic effect of the conjugate was calculated by the combination index method described by Chou-Talalay. This hybrid nanoantibiotic opens a new front against multidrug-resistant pathogens.

Curcumin Encapsulated PEGylated Nanoliposomes: A Potential Anti-Infective Therapeutic Agent

Exploration of novel bioactive molecules or potentiation of the existing bioactive molecules is necessary to reduce the burden of the infectious diseases for the better human health. Curcumin is a promising molecule with huge therapeutic potential. Despite high bioactivity, its therapeutic suitability is shadowed by poor bioavailability, limited aqueous solubility, and short shelf life. Nanotechnology has generated new avenues to overcome these challenges. In the current study polymer assisted nanoliposomes, PEGylated Curcumin nanoliposomes with good loading efficiency were prepared. These particles have shown 1000 fold enhanced curcumin hydrophilicity and tenfold higher stability. In vitro release kinetic indicates two fold higher curcumin release in the simulated gastric and intestinal environment. Various bioactivity assays have confirmed enhanced bioactivity of nanocurcmin in comparison of the native curcumin. PEGylated Curcumin nanoliposomes could be employed for treating various diseases.

Release and cytotoxicity studies of magnetite/Ag/antibiotic nanoparticles: An interdependent relationship

Though the cytotoxic properties of magnetite nanoparticles (NPs) are rather well investigated and known to be dose dependent and rather low, surface functionalization can drastically change their properties. To determine whether the cytotoxicity of magnetite/Ag/antibiotic NPs may be associated, among other things, with iron, silver and antibiotic release, this study investigates the release profiles and cytotoxicity of magnetite/Ag/rifampicin and magnetite/Ag/doxycycline NPs compares it similar profiles from magnetite, magnetite/Ag NPs and antibiotics. It was established that the studied NPs released not only water-soluble substances, such as antibiotics, but also poorly-soluble ones, such as iron and silver. The deposition of silver on the magnetite surface promotes the release of iron by the formation of a galvanic couple. Antibiotic adsorbed on the magnetite/Ag surface plays a dual role in the galvanic corrosion processes: as a corrosion inhibitor for iron oxides and as a corrosion promoter for silver. Magnetite/Ag/rifampicin and magnetite/Ag/doxycycline. NPs were found to have greater cytotoxicity towards the HEK293T cell line than magnetite NPs. These results were attributed to the combined toxic action of the released iron, silver ions and antibiotics. Intensive and simultaneous release of the NP components caused cell stress and suppressed their growth.

Synthesis and characterization of magnetite/silver/antibiotic nanocomposites for targeted antimicrobial therapy

The article is devoted to preparation and characterization of magnetite/silver/antibiotic nanocomposites for targeted antimicrobial therapy. Magnetite nanopowder was produced by thermochemical technique; silver was deposited on the magnetite nanoparticles in the form of silver clusters. Magnetite/silver nanocomposite was investigated by XRD, SEM, TEM, AFM, XPS, EDX techniques. Adsorptivity of magnetite/silver nanocomposite towards seven antibiotics from five different groups was investigated. It was shown that rifampicin, doxycycline, ceftriaxone, cefotaxime and doxycycline may be attached by physical adsorption to magnetite/silver nanocomposite. Electrostatic surfaces of antibiotics were modeled and possible mechanism of antibiotic attachment is considered in this article. Raman spectra of magnetite, magnetite/silver and magnetite/silver/antibiotic were collected. It was found that it is difficult to detect the bands related to antibiotics in the magnetite/silver/antibiotic nanocomposite spectra due to their overlap by the broad carbon bands of magnetite nanopowder. Magnetic measurements revealed that magnetic saturation of the magnetite/silver/antibiotic nanocomposites decreased on 6-19 % in comparison with initial magnetite nanopowder. Pilot study of antimicrobial properties of the magnetite/silver/antibiotic nanocomposites were performed towards Bacillus pumilus.

Bacteriagenic silver nanoparticles: synthesis, mechanism, and applications

Silver nanoparticles (AgNPs) have received tremendous attention due to their significant antimicrobial properties. Large numbers of reports are available on the physical, chemical, and biological syntheses of colloidal AgNPs. Since there is a great need to develop ecofriendly and sustainable methods, biological systems like bacteria, fungi, and plants are being employed to synthesize these nanoparticles. The present review focuses specifically on bacteria-mediated synthesis of AgNPs, its mechanism, and applications. Bacterial synthesis of extra- and intracellular AgNPs has been reported using biomass, supernatant, cell-free extract, and derived components. The extracellular mode of synthesis is preferred over the intracellular mode owing to easy recovery of nanoparticles. Silver-resistant genes, c-type cytochromes, peptides, cellular enzymes like nitrate reductase, and reducing cofactors play significant roles in AgNP synthesis in bacteria. Organic materials released by bacteria act as natural capping and stabilizing agents for AgNPs, thereby preventing their aggregation and providing stability for a longer time. Regulation over reaction conditions has been suggested to control the morphology, dispersion, and yield of nanoparticles. Bacterial AgNPs have anticancer and antioxidant properties. Moreover, the antimicrobial activity of AgNPs in combination with antibiotics signifies their importance in combating the multidrug-resistant pathogenic microorganisms. Multiple microbicidal mechanisms exhibited by AgNPs, depending upon their size and shape, make them very promising as novel nanoantibiotics.