Antibacterial, antibiofilm, and anticancer activity of silver-nanoparticles synthesized from the cell-filtrate of Streptomyces enissocaesilis.

Silver nanoparticles (Ag-NPs) have a unique mode of action as antibacterial agents in addition to their anticancer and antioxidant properties. In this study, microbial nanotechnology is employed to synthesize Ag-NPs using the cell filtrate of Streptomyces enissocaesilis BS1. The synthesized Ag-NPs are confirmed by ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Also, the effects of different factors on Ag-NPs synthesis were evaluated to set the optimum synthesis conditions. Also, the antibacterial, antibiofilm, and anticancer activity of Ag-NPs was assessed. The X-ray diffraction (XRD) analysis confirmed the crystalline nature of the sample and validated that the crystal structure under consideration is a face-centered cubic (FCC) pattern. The TEM examination displayed the spherical particles of the Ag-NPs and their average size, which is 32.2 nm. Fourier transform infrared spectroscopy (FTIR) revealed significant changes in functionality after silver nanoparticle dispersion, which could be attributed to the potency of the cell filtrate of Streptomyces enissocaesilis BS1 to act as both a reducing agent and a capping agent. The bioactivity tests showed that our synthesized Ag-NPs exhibited remarkable antibacterial activity against different pathogenic strains. Also, when the preformed biofilms of Pseudomonas aeruginosa ATCC 9027, Salmonella typhi ATCC 12023, Escherichia coli ATCC 8739, and Staphylococcus aureus ATCC 6598 were exposed to Ag NPs 50 mg/ml for 24 hours, the biofilm biomass was reduced by 10.7, 34.6, 34.75, and 39.08%, respectively. Furthermore, the Ag-NPs showed in vitro cancer-specific sensitivity against human breast cancer MCF-7 cell lines and colon cancer cell line Caco-2, and the IC50 was 0.160 mg/mL and 0.156 mg/mL, respectively. The results of this study prove the ease and efficiency of the synthesis of Ag-NPs using actinomycetes and demonstrate the significant potential of these Ag-NPs as anticancer and antibacterial agents.

Probiotic potential of Streptomyces levis strain HFM-2 isolated from human gut and its antibiofilm properties against pathogenic bacteria.

BACKGROUND: Antimicrobial resistance (AMR) is a serious worldwide public health concern that needs immediate action. Probiotics could be a promising alternative for fighting antibiotic resistance, displaying beneficial effects to the host by combating diseases, improving growth, and stimulating the host immune responses against infection. This study was conducted to evaluate the probiotic, antibacterial, and antibiofilm potential of Streptomyces levis strain HFM-2 isolated from the healthy human gut. RESULTS: In vitro antibacterial activity in the cell-free supernatant of S. levis strain HFM-2 was evaluated against different pathogens viz. K. pneumoniae sub sp. pneumoniae, S. aureus, B. subtilis, VRE, S. typhi, S. epidermidis, MRSA, V. cholerae, M. smegmatis, E. coli, P. aeruginosa and E. aerogenes. Further, the ethyl acetate extract from S. levis strain HFM-2 showed strong biofilm inhibition against S. typhi, K. pneumoniae sub sp. pneumoniae, P. aeruginosa and E. coli. Fluorescence microscopy was used to detect biofilm inhibition properties. MIC and MBC values of EtOAc extract were determined at 500 and 1000 µg/mL, respectively. Further, strain HFM-2 showed high tolerance in gastric juice, pancreatin, bile, and at low pH. It exhibited efficient adhesion properties, displaying auto-aggregation (97.0%), hydrophobicity (95.71%, 88.96%, and 81.15% for ethyl acetate, chloroform and xylene, respectively), and showed 89.75%, 86.53%, 83.06% and 76.13% co-aggregation with S. typhi, MRSA, S. pyogenes and E. coli, respectively after 60 min of incubation. The S. levis strain HFM-2 was susceptible to different antibiotics such as tetracycline, streptomycin, kanamycin, ciprofloxacin, erythromycin, linezolid, meropenem, amikacin, gentamycin, clindamycin, moxifloxacin and vancomycin, but resistant to ampicillin and penicillin G. CONCLUSION: The study shows that S. levis strain HFM-2 has significant probiotic properties such as good viability in bile, gastric juice, pancreatin environment, and at low pH; proficient adhesion properties, and antibiotic susceptibility. Further, the EtOAc extract of Streptomyces levis strain HFM-2 has a potent antibiofilm and antibacterial activity against antibacterial-resistant clinical pathogens.

Peptide-based strategies for overcoming biofilm-associated infections: a comprehensive review.

Biofilms represent resilient microbial communities responsible for inducing chronic infections in human subjects. Given the escalating challenges associated with antibiotic therapy failures in clinical infections linked to biofilm formation, a peptide-based approach emerges as a promising alternative to effectively combat these notoriously resistant biofilms. Contrary to conventional antimicrobial peptides, which predominantly target cellular membranes, antibiofilm peptides necessitate a multifaceted approach, addressing various "biofilm-specific factors." These factors encompass Extracellular Polymeric Substance (EPS) degradation, membrane targeting, cell signaling, and regulatory mechanisms. Recent research endeavors have been directed toward assessing the potential of peptides as potent antibiofilm agents. However, to translate these peptides into viable clinical applications, several critical considerations must be meticulously evaluated during the peptide design process. This review serves to furnish an all-encompassing summary of the pivotal factors and parameters that necessitate contemplation for the successful development of an efficacious antibiofilm peptide.

Antibiofilm and wound healing efficacy of rhamnolipid biosurfactant against pathogenic bacterium Staphylococcus aureus.

The present study evaluates the in-vitro antibiofilm activity against the biofilm formed by Staphylococcus aureus, and the wound-healing efficacy of two different types of rhamnolipids produced by Pseudomonas aeruginosa strain JS29 in S.aureus infected wounds. The biosurfactant production was carried out in a mineral salt medium supplemented with 2 % Glucose and 2 % Glycerol individually and thus were designated as RL-Glu and RL-Gly respectively. 0.5 mg/ml of RL-Glu and RL-Gly demonstrated 90 % growth inhibition of S. aureus while exhibiting bactericidal activity at 4 mg/ml of RL-Glu and 1 mg/ml of RL-Gly. Both types of rhamnolipid cause changes in membrane permeability leading to pathogens' non-viability. 90 % inhibition of biofilm formation by S. aureus was observed at 2 mg/ml of RL-Glu and 0.5 mg/ml of RL-Gly, while 0.5 mg/ml of both rhamnolipid disrupted 90 % of the preformed biofilm. 0.5 mg/ml of RL-Glu and RL-Gly decreases the production of exopolysaccharides and also causes structural alteration. 0.5 mg/ml of RL-Glu and RL-Gly were found to exhibit effective wound healing efficacy in S. aureus infected wounds within 7 days of treatment. Histopathological studies of wound sites revealed efficient wound management by both the rhamnolipid. LCMS and GCMS characterization of the biosurfactant revealed that JS29 produces different rhamnolipid congeners when grown on different carbon sources, thereby influencing the antimicrobial, antibiofilm, and wound healing efficacy of rhamnolipid.

Role of small molecules and nanoparticles in effective inhibition of microbial biofilms: A ray of hope in combating microbial resistance.

Microbial biofilms pose a severe threat to global health, as they are associated with deadly chronic infections and antibiotic resistance. To date, very few drugs are in clinical practice that specifically target microbial biofilms. Therefore, there is an urgent need for the development of novel therapeutic options targeting biofilm-related infections. In this review, we discuss nearly seventy-five different molecular scaffolds published over the last decade (2010-2023) which have exhibited their biofilm inhibition potential. For convenience, we have classified these into five different sub-groups based on their origin and design (excluding peptides as they are placed in between small molecules and biologics), namely, heterocycles; inorganic small molecules & metal complexes; small molecules decorated nanoparticles; small molecules derived from natural products (both plant and marine sources); and small molecules designed by in-silico approach. These antibiofilm agents are capable of disrupting microbial biofilms and can offer a promising avenue for future developments in human medicine. A hitherto review of this kind will lay a platform for the researchers to find new molecular entities to curb the serious menace of antimicrobial resistance especially caused by biofilms.

Theaflavin-3,3'-digallate effectively attenuates biofilm formation by Enterococcus faecalis via the targeting of specific quorum sensing pathways.

Enterococcus faecalis, an opportunistic pathogen responsible for nosocomial infections, exhibits increased pathogenicity via biofilm formation. Theaflavin-3,3'-digallate (TF3), a theaflavin extracted from black tea, exhibits potent antibacterial effects. In the present study, we investigated the inhibitory effect of TF3 on E. faecalis. Our results indicated that TF3 significantly inhibited E. faecalis ATCC 29212 biofilm formation. This observation was further confirmed via crystal violet staining, confocal laser scanning microscopy, and field emission-scanning electron microscopy. To disclose the underlying mechanisms, RNA-seq was applied. TF3 treatment significantly altered the transcriptomic profile of E. faecalis, as evidenced by identification of 248 differentially expressed genes (DEGs). Through functional annotation of these DEGs, several quorum-sensing pathways were found to be suppressed in TF3-treated cultures. Further, gene expression verification via real-time PCR confirmed the downregulation of gelE, sprE, and secY by TF3. These findings highlighted the ability of TF3 to impede E. faecalis biofilm formation, suggesting a novel preventive strategy against E. faecalis infections.

The anti-quorum sensing and biofilm inhibitory potential of Piper betle L. leaf extract and prediction of the roles of the potent phytocompounds.

The leaves of Piper betle L., known as betel leaf, have immense medicinal properties. It possesses potent antimicrobial efficacies and can be a valuable tool to combat drug-resistant microorganisms. Quorum sensing (QS) inhibition is one of the best strategies to combat drug resistance. The present study investigates the anti-quorum sensing and biofilm inhibitory potential of Piper betle L. leaf extract against two bacterial strains, Chromobacterium violaceum and Pseudomonas aeruginosa. The extract produced substantial QS-inhibition zones in a biosensor strain of C. violaceum (CV026), indicating interference with quorum-sensing signals. The Results demonstrated significant inhibition in biofilm formation and different QS-regulated virulence factors (violacein, exopolysaccharides, pyocyanin, pyoverdine, elastase) in both C. violaceum and P. aeruginosa at sub-MIC concentrations of the extract and tetracycline, an antibiotic with known anti-QS activity. The quantitative real-time PCR (qRT-PCR) revealed decreased gene expression in different QS-related genes in C. violaceum (cviI, cviR, and vioA) and P. aeruginosa (lasI, lasR, lasB, rhlI, rhlR, and rhlA) strains after treatment. Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified the significant phytocompounds, mainly derivatives of chavicol and eugenol, in the extract. Of these compounds, chavicol acetate (affinity: -7.00 Kcal/mol) and acetoxy chavicol acetate (affinity: -7.87 Kcal/mol) showed the highest potential to bind with the CviR and LasR protein, respectively, as evident from the in-silico molecular docking experiment. The findings of this endeavour highlight the promising role of Piper betle L. as a source of natural compounds with anti-quorum sensing properties against pathogenic bacteria, opening avenues for developing novel therapeutic agents to combat bacterial infections.

Beyond antibiotics: Emerging antivirulence strategies to combat Pseudomonas aeruginosa in cystic fibrosis.

Pseudomonas aeruginosa is an opportunistic pathogen that poses a significant threat to individuals suffering from cystic fibrosis (CF). The pathogen is highly prevalent in CF individuals and is responsible for chronic infection, resulting in severe tissue damage and poor patient outcome. Prolonged antibiotic administration has led to the emergence of multidrug resistance in P. aeruginosa. In this direction, antivirulence strategies achieving targeted inhibition of bacterial virulence pathways, including quorum sensing, efflux pumps, lectins, and iron chelators, have been explored against CF isolates of P. aeruginosa. Hence, this review article presents a bird's eye view on the pulmonary infections involving P. aeruginosa in CF patients by laying emphasis on factors contributing to bacterial colonization, persistence, and disease progression along with the current line of therapeutics against P. aeruginosa in CF. We further collate scientific literature and discusses various antivirulence strategies that have been tested against P. aeruginosa isolates from CF patients.

Citral and triclosan synergistically silence quorum sensing and potentiate antivirulence response in Pseudomonas aeruginosa.

Among the ESKAPE pathogens, Pseudomonas aeruginosa is an extensively notorious superbug that causes difficult-to-treat infections. Since quorum sensing (QS) directly promotes pseudomonal virulence, targeting QS circuits is a promising approach for disarming phenotypic virulence. Hence, this study scrutinizes the anti-QS, antivirulence, and anti-biofilm potential of citral (CiT; phytochemical) and triclosan (TcN; disinfectant), alone and in combination, against P. aeruginosa PAO1/PA14. The findings confirmed synergism between CiT and TcN and revealed their quorum quenching (QQ) potential. At sub-inhibitory levels, CiT-TcN combination significantly impeded pyocyanin, total bacterial protease, hemolysin, and pyochelin production alongside inhibiting biofilm formation in P. aeruginosa. Moreover, the QQ and antivirulence potential of CiT and TcN was positively correlated by molecular docking studies that predicted strong associations of the drugs with QS receptors of P. aeruginosa. Collectively, the study identifies CiT-TcN as an effective drug combination that harbors QQ, antivirulence, and anti-biofilm prospects against P. aeruginosa.

Biofilm inhibition/eradication: exploring strategies and confronting challenges in combatting biofilm.

Biofilms are complex communities of microorganisms enclosed in a self-produced extracellular matrix, posing a significant threat to different sectors, including healthcare and industry. This review provides an overview of the challenges faced due to biofilm formation and different novel strategies that can combat biofilm formation. Bacteria inside the biofilm exhibit increased resistance against different antimicrobial agents, including conventional antibiotics, which can lead to severe problems in livestock and animals, including humans. In addition, biofilm formation also imposes heavy economic pressure on industries. Hence it becomes necessary to explore newer alternatives to eradicate biofilms effectively without applying selection pressure on the bacteria. Excessive usage of antibiotics may also lead to an increase in the number of resistant strains as bacteria employ an advanced antimicrobial resistance mechanism. This review provides insight into multifaceted technologies like quorum sensing inhibition, enzymes, antimicrobial peptides, bacteriophage, phytocompounds, and nanotechnology to neutralize biofilms without developing antimicrobial resistance (AMR). Furthermore, it will pave the way for developing newer therapeutic agents to deal with biofilms more efficiently.

Quantum dots: a next generation approach for pathogenic microbial biofilm inhibition; mechanistic insights, existing challenges, and future potential.

Quantum Dots (QDs) have emerged as versatile nanomaterials with origins spanning organic, inorganic, and natural sources, revolutionizing various biomedical applications, particularly in combating pathogenic biofilm formation. Biofilms, complex structures formed by microbial communities enveloped in exopolysaccharide matrices, pose formidable challenges to traditional antibiotics due to their high tolerance and resistance, exacerbating inefficacy issues in antibiotic treatments. QDs offer a promising solution, employing physical mechanisms like photothermal or photodynamic therapy to disrupt biofilms. Their efficacy is noteworthy, with lower susceptibility to resistance development and broad-spectrum action as compared to conventional antibiotic methods. The stability and durability of QDs ensure sustained biofilm activity, even in challenging environmental conditions. This comprehensive review delves into the synthesis, properties, and applications of Carbon Quantum Dots (CQDs), most widely used QDs, showcasing groundbreaking developments that position these nanomaterials at the forefront of cutting-edge research and innovation. These nanomaterials exhibit multifaceted mechanisms, disrupting cell walls and membranes, generating reactive oxygen species (ROS), and binding to nucleic materials, effectively inhibiting microbial proliferation. This opens transformative possibilities for healthcare interventions by providing insights into biofilm dynamics. However, challenges in size control necessitate ongoing research to refine fabrication techniques, ensure defect-free surfaces, and optimize biological activity. QDs emerge as microscopic yet potent tools, promising to contribute to a brighter future where quantum wonders shape innovative solutions to persistently challenging issues posed by pathogenic biofilms. Henceforth, this review aims to explore QDs as potential agents for inhibiting pathogenic microbial biofilms, elucidating the underlying mechanisms, addressing the current challenges, and highlighting their promising future potential.

Green synthesis of silver nanoparticles from discarded shells of velvet tamarind (Dialium cochinchinense) and their antimicrobial synergistic potentials and biofilm inhibition properties.

In the field of nanomedicine, biogenic metal nanoparticles are commonly synthesized using edible plant products as bio-reducing or stabilizing agents. In this study, discarded shell of velvet tamarind fruit is explored as a potent reducing agent for biogenic synthesis of silver nanoparticles (VeV-AgNPs). Silver nanoparticles were formed in minutes under sunlight exposure, which was considerably fast compared to under ambient conditions. The optical, structural and morphological studies revealed that the nanoparticle colloidal solution consisted of particles with quasi-spherical and rodlike morphologies. To investigate antimicrobial properties, eight microorganisms were exposed to the VeV-AgNPs. The results indicated that VeV-AgNPs had enhanced antimicrobial activity, with a recorded minimum inhibitory concentration (MIC) of 3.9 µg/mL against E. coli. Further studies were conducted to examine the biofilm inhibition properties and synergistic effect of the VeV-AgNPs. The findings showed a biofilm inhibition potential of around 98% against E. coli, and the particles were also found to increase the efficacy of standard antimicrobial agents. The combinatory effect with standard antifungal and antibacterial agents ranged from synergistic to antagonistic effects against the tested microorganisms. These results suggest that silver nanoparticles produced from discarded shells of velvet tamarind are potent and could be used as a potential drug candidate to combat antimicrobial resistance.

The inhibition mechanism of co-cultured probiotics on biofilm formation of Klebsiella pneumoniae.

AIMS: Klebsiella pneumoniae, an important opportunistic pathogen of nosocomial inflection, is known for its ability to form biofilm. The purpose of the current study is to assess how co- or mono-cultured probiotics affect K. pneumoniae's ability to produce biofilms and investigate the potential mechanisms by using a polyester nonwoven chemostat and a Caco-2 cell line. METHODS AND RESULTS: Compared with pure cultures of Lactobacillus rhamnosus and Lactobacillus sake, the formation of K. pneumoniae biofilm was remarkably inhibited by the mixture of L. rhamnosus, L. sake, and Bacillus subtilis at a ratio of 5:5:1 by means of qPCR and FISH assays. In addition, Lactobacillus in combination with B. subtilis could considerably reduce the adherence of K. pneumoniae to Caco-2 cells by using inhibition, competition, and displacement assays. According to the RT-PCR assay, the adsorption of K. pneumoniae to Caco-2 cells was effectively inhibited by the co-cultured probiotics, leading to significant reduction in the expression of proinflammatory cytokines induced by K. pneumoniae. Furthermore, the HPLC and RT-PCR analyses showed that the co-cultured probiotics were able to successfully prevent the expression of the biofilm-related genes of K. pneumoniae by secreting plenty of organic acids as well as the second signal molecule (c-di-GMP), resulting in inhibition on biofilm formation. CONCLUSION: Co-culture of L. sake, L. rhamnosus, and B. subtilis at a ratio of 5:5:1 could exert an antagonistic effect on the colonization of pathogenic K. pneumoniae by down-regulating the expression of biofilm-related genes. At the same time, the co-cultured probiotics could effectively inhibit the adhesion of K. pneumoniae to Caco-2 cells and block the expression of proinflammatory cytokines induced by K. pneumoniae.

Combination antimicrobial therapy: in vitro synergistic effect of anti-staphylococcal drug oxacillin with antimicrobial peptide nisin against Staphylococcus epidermidis clinical isolates and Staphylococcus aureus biofilms.

The ability of Staphylococcus epidermidis and S. aureus to form strong biofilm on plastic devices makes them the major pathogens associated with device-related infections (DRIs). Biofilm-embedded bacteria are more resistant to antibiotics, making biofilm infections very difficult to effectively treat. Here, we evaluate the in vitro activities of anti-staphylococcal drug oxacillin and antimicrobial peptide nisin, alone and in combination, against methicillin-resistant S. epidermidis (MRSE) clinical isolates and the methicillin-resistant S. aureus ATCC 43,300. The minimum inhibitory concentrations (MIC) and minimum biofilm eradication concentrations (MBEC) of oxacillin and nisin were determined using the microbroth dilution method. The anti-biofilm activities of oxacillin and nisin, alone or in combination, were evaluated. In addition, the effects of antimicrobial agents on the expression of icaA gene were examined by quantitative real-time PCR. MIC values for oxacillin and nisin ranged 4-8 µg/mL and 64-128 µg/mL, respectively. Oxacillin and nisin reduced biofilm biomass in all bacteria in a dose-dependent manner and this inhibitory effect was enhanced with combinatorial treatment. MBEC ranges for oxacillin and nisin were 2048-8192 µg/mL and 2048-4096 µg/mL, respectively. The addition of nisin significantly decreased the oxacillin MBECs from 8- to 32-fold in all bacteria. At the 1× MIC and 1/2× MIC, both oxacillin and nisin decreased significantly the expression of icaA gene in comparison with untreated control. When two antimicrobial agents were combined at 1/2× MIC concentration, the expression of icaA were significantly lower than when were used alone. Nisin/conventional oxacillin combination showed considerable anti-biofilm effects, including inhibition of biofilm formation, eradication of mature biofilm, and down-regulation of biofilm-related genes, proposing its applications for treating or preventing staphylococcal biofilm-associated infections, including device-related infections.

Design and synthesis of new quinazolinone derivatives: investigation of antimicrobial and biofilm inhibition effects.

New quinazolin-4-ones 9-32 were synthesized in an attempt to overcome the life-threatening antibiotic resistance phenomenon. The antimicrobial screening revealed that compounds 9, 15, 16, 18, 19, 20 and 29 are the most broad spectrum antimicrobial agents in this study with safe profile on human cell lines. Additionally, compounds 19 and 20 inhibited biofilm formation in Pseudomonas aeruginosa, which is regulated by quorum sensing system, at sub-minimum inhibitory concentrations (sub-MICs) with IC50 values 3.55 and 6.86 µM, respectively. By assessing other pseudomonal virulence factors suppression, it was found that compound 20 decreased cell surface hydrophobicity compromising bacterial cells adhesion, while both compounds 19 and 20 curtailed the exopolysaccharide production which constitutes the major component of the matrix binding biofilm components together. Also, at sub-MICs Pseudomonas cells twitching motility was impeded by compounds 19 and 20, a trait which augments the cells pathogenicity and invasion potential. Molecular docking study was performed to further evaluate the binding mode of candidates 19 and 20 as inhibitors of P. aeruginosa quorum sensing transcriptional regulator PqsR. The achieved results demonstrate that both compounds bear promising potential for discovering new anti-biofilm and quorum quenching agents against Pseudomonas aeruginosa without triggering resistance mechanisms as the normal bacterial life cycle is not disturbed.

Lachnuoic Acids A-F: Ambuic Acid Congeners from a Saprotrophic Lachnum Species.

Chemical prospection of an extract derived from a saprotrophic fungus Lachnum sp. IW157 resulted in the isolation and characterization of six unprecedentedly reported ambuic acid analogues named lachnuoic acids A-F (1-6). Chemical structures of 1-6 were determined based on comprehensive 1D and 2D NMR spectroscopic analyses together with HR-ESI-MS spectrometry. The relative configurations of 1-3 were defined by ROESY spectroscopic analyses while their absolute configurations were unambiguously determined by Mosher's esters method. All isolated compounds were subjected to cytotoxic, antimicrobial, antibiofilm and nematicidal activity assays where only lachnuoic acid A (1) revealed potent antimicrobial activity against Staphylococcus aureus and Bacillus subtilis at MIC values of 16.6 and 8.3 µg/mL, respectively.

Phytofabrication of biocompatible zinc oxide nanoparticle using Gymnema sylvestre and its potent in vitro antibacterial, antibiofilm, and cytotoxicity against human breast cancer cells (MDA-MB-231).

The increasing incidence of breast cancer and bacterial biofilm in medical devices significantly heightens global mortality and morbidity, challenging synthetic drugs. Consequently, greener-synthesized nanomaterials have emerged as a versatile alternative for various biomedical applications, offering new therapeutic avenues. This study explores the synthesis of biocompatible zinc oxide (ZnONPs) nanoparticles using Gymnema sylvestre and its antibacterial, antibiofilm, and cytotoxic properties. Characterization of ZnONPs inferred that UV-Vis spectra exhibited a sharp peak at 370 nm. Fourier transform infrared spectroscopical analysis revealed the presence of active functional groups such as aldehyde, alkyne, cyclic alkene, sulfate, alkyl aryl ether, and Zn-O bonds. X-ray diffraction analysis results confirmed the crystalline nature of the nanoparticle. Scanning electron microscope analysis evidenced hexagonal morphology, and energy-dispersive X-ray analysis confirmed zinc content. High-resolution transmission electron microscope analysis showed hexagonal and rod-shaped ZnONPs with a size of 5 nm. Zeta potential results affirmed the stability of nanoparticles. The ZnONPs effectively inhibited gram-positive (18-20 mm) than gram-negative (12-18 mm) bacterial pathogens with lower bacteriostatic and higher bactericidal values. Biofilm inhibitory property inferred ZnONPs were more effective against gram-positive (38-94%) than gram-negative bacteria (27-86%). The concentration of ZnONPs to exert 50% biofilm-inhibitory is lower against gram-positive bacteria (179.26-203.95 µg/mL) than gram-negative bacteria (201.46-236.19 µg/mL). Microscopic visualization inferred that at 250 µg/mL, ZnONPs strongly disrupted biofilm formation, as evidenced by decreased biofilm density and altered architecture. The cytotoxicity of ZnONPs against breast cancer cells showed a dose-dependent reduction in cell viability with an IC50 value of 19.4 µg/mL. AO/EB staining indicated early and late apoptotic cell death of breast cancer cells under fluorescence microscopy. The results of hemolytic activity validated the biocompatibility of the ZnONPs. Thus, the unique properties of the green-synthesized ZnONPs suggest their potential as effective drug carriers for targeted delivery in cancer therapy and the treatment of biofilm-related infections.

Plantago major and Plantago lanceolata Exhibit Antioxidant and Borrelia burgdorferi Inhibiting Activities.

Lyme disease, caused by Borrelia burgdorferi sensu lato infection, is the most widespread vector-borne illness in the Northern Hemisphere. Unfortunately, using targeted antibiotic therapy is often an ineffective cure. The antibiotic resistance and recurring symptoms of Lyme disease are associated with the formation of biofilm-like aggregates of B. burgdorferi. Plant extracts could provide an effective alternative solution as many of them exhibit antibacterial or biofilm inhibiting activities. This study demonstrates the therapeutic potential of Plantago major and Plantago lanceolata as B. burgdorferi inhibitors. Hydroalcoholic extracts from three different samples of each plant were first characterised based on their total concentrations of polyphenolics, flavonoids, iridoids, and antioxidant capacity. Both plants contained substantial amounts of named phytochemicals and showed considerable antioxidant properties. The major non-volatile constituents were then quantified using HPLC-DAD-MS analyses, and volatile constituents were quantified using HS-SPME-GC-MS. The most prevalent non-volatiles were found to be plantamajoside and acteoside, and the most prevalent volatiles were ß-caryophyllene, D-limonene, and α-caryophyllene. The B. burgdorferi inhibiting activity of the extracts was tested on stationary-phase B. burgdorferi culture and its biofilm fraction. All extracts showed antibacterial activity, with the most effective lowering the residual bacterial viability down to 15%. Moreover, the extracts prepared from the leaves of each plant additionally demonstrated biofilm inhibiting properties, reducing its formation by 30%.

Is Silver Addition to Scaffolds Based on Polycaprolactone Blended with Calcium Phosphates Able to Inhibit Candida albicans and Candida auris Adhesion and Biofilm Formation?

Candida spp. periprosthetic joint infections are rare but difficult-to-treat events, with a slow onset, unspecific symptoms or signs, and a significant relapse risk. Treatment with antifungals meets with little success, whereas prosthesis removal improves the outcome. In fact, Candida spp. adhere to orthopedic devices and grow forming biofilms that contribute to the persistence of this infection and relapse, and there is insufficient evidence that the use of antifungals has additional benefits for anti-biofilm activity. To date, studies on the direct antifungal activity of silver against Candida spp. are still scanty. Additionally, polycaprolactone (PCL), either pure or blended with calcium phosphate, could be a good candidate for the design of 3D scaffolds as engineered bone graft substitutes. Thus, the present research aimed to assess the antifungal and anti-biofilm activity of PCL-based constructs by the addition of antimicrobials, for instance, silver, against C. albicans and C. auris. The appearance of an inhibition halo around silver-functionalized PCL scaffolds for both C. albicans and C. auris was revealed, and a significant decrease in both adherent and planktonic yeasts further demonstrated the release of Ag+ from the 3D constructs. Due to the combined antifungal, osteoproliferative, and biodegradable properties, PCL-based 3D scaffolds enriched with silver showed good potential for bone tissue engineering and offer a promising strategy as an ideal anti-adhesive and anti-biofilm tool for the reduction in prosthetic joints of infections caused by Candida spp. by using antimicrobial molecule-targeted delivery.

Novel extracellular synthesized silver nanoparticles using thermophilic Anoxybacillus flavithermus and Geobacillus stearothermophilus and their evaluation as nanodrugs.

In this investigation, two new thermophilic bacteria were isolated. The new isolates were characterized by 16S rRNA, biochemical, morphological, and physiological analyzes and the isolates were identified as Geobacillus stearothermophilus strain Gecek20 and thermophilic Anoxybacillus flavithermus strain Gecek19. Various biological activities of extracellular Ag-NPs synthesized from thermophilic G. stearothermophilus strain Gecek20 and thermophilic A. flavithermus strain Gecek19 were evaluated. The produced NPs were analyzed by SEM, SEM-EDX, and XRD analyses. The antioxidant abilities of new synthesized Ag-NPs from thermophilic G. stearothermophilus strain Gecek20 (T1-Ag-NPs) and new synthesized Ag-NPs from thermophilic A. flavithermus strain Gecek19 (T2-Ag-NPs) were studied by DPPH inhibition and metal chelating ability. The highest DPPH and metal chelating abilities of T1-Ag-NPs and T2-Ag-NPs at 200 mg/L concentration were 93.17 and 90.85%, and 75.80 and 83.64%, respectively. The extracellular green synthesized T1-Ag-NPs and T2-AgN-Ps showed DNA nuclease activity at all tested concentrations. Moreover, both new synthesized Ag-NPs had antimicrobial activity against the strains studied, especially on Gram positive bacteria. T1-Ag-NPs and T2-AgNPs also showed powerful Escherichia coli growth inhibition. The highest biofilm inhibition percentages of T1-Ag-NPs and T2-Ag-NPs against Pseudomonas aeruginosa and Staphylococcus aureus were 100.0%, respectively, at 500 mg/L.