Investigating the Production of Antimicrobial Nanoparticles by Chlorella vulgaris and the Link to Its Loss of Viability

Chlorella vulgaris from Al-Ahsa, KSA was proved to be an active silver and gold nanoparticle producer. Nanogold and nanosilver particles were characterized using UV-visible spectroscopy, Fourier-transform infrared spectroscopy, and scanning electronmicroscopy. Both nanoparticles were used in the antimicrobial bioassay. The two nanoparticles showed antibacterial activities, with the silver nanoparticles being the most effective. To investigate the argumentative nature of their biosynthesis (i.e., whether it is a biotic or abiotic process), we isolated total ribonucleic acid RNA as an indicator of vitality. RNA was completely absent in samples taken after one week of incubation with silver nitrate and even after one or two days. However, successful extraction was only achievable in samples taken after incubation for one and four hours with silver nitrate. Most importantly, the gel image showed recognizable shearing of the nucleic acid after 4 h as compared to the control. An assumption can be drawn that the synthesis of nanoparticles may start biotically by the action of enzyme(s) and abiotically by action of reducing entities. Nonetheless, with prolonged incubation, excessive nanoparticle accumulation can be deadly. Hence, their synthesis continues abiotically. From the RNA banding profile, we suggest that nanosilver production starts both biotically and abiotically in the first few hours of incubation and then continues abiotically. Nanosilver particles proved to have more of an antimicrobial impact than nanogold and hence are recommended for different applications as antibacterial agents.

Intake of nanoparticles and impact on gut microbiota: in vitro and animal models available for testing

ABSTRACT The oral delivery of compounds associated with diet or medication have an impact on the gut microbiota balance, which in turn, influences the physiologic process. Several reports have shown significant advances in clarifying the impact, interactions and outcomes of oral intake of nanoparticles and the human gut. These interactions may affect the bioavailability of the delivered compounds. In addition, there is a considerable breakthrough in the development of antimicrobial nanoparticles for intestinal pathogenic bacteria. Several in vitro fermentation and in vivo models have been developed throughout the years and were used to test these systems. The methodologies and studies carried out so far on the modulation of human and animal gut microbiome by oral delivery nanosized materials were reviewed. Overall, the available in vitro studies mimic the real physiological events enabling to select the best production conditions of nanoparticulate systems in a preliminary stage of research. On the other hand, animal studies can be used to access the dosage effect, safety and correlation between haematological, biochemical and symptoms, with gut microbiota groups and metabolites.

Influence of Antimicrobial Nanoparticles on Flexural Strength and Hardness of Polymethylmethacrylate

BACKGROUND: Polymethylmethacrylate (PMMA) is commonly used for dental appliances but has several shortcomings that could benefit from improvement with the use of nanoparticles (NPs). AIM: The purpose of this study was to modify PMMA with three different antimicrobial NPs; Graphene oxide nanosheets (nGO), Titanium dioxide NPs (TiO2 NPs) and curcumin (CUR)-loaded graphene oxide nanosheets alone, and in combination and assess the flexural strength and hardness of the different groups. MATERIALS AND METHODS: The material used in this study was chemically cured PMMA that was modified with nGO, TiO2 NPs and GOCUR alone and in combination to give 6 groups; Group A: PMMA, Group B: PMMA with nGO, Group C: PMMA with TiO2 NPs, Group D: PMMA with TiO2 and GO NPs, Group E: PMMA with GOCUR, and Group F: PMMA with TiO2 NP, and GOCUR. The Six groups were tested for flexural strength and hardness. Statistical analysis was and data were expressed as means and standard deviation. Data was explored for normality using the Kolmogorov-Smirnov test of normality. The ANOVA test was used to compare between groups, followed by Bonferroni’s post hoc test for pairwise comparison. The significance level was set at p ≤ 0.05. RESULTS: The highest flexural strength was recorded in Group C (52.26 ± 5.48 MPa) and the lowest value was in Group A (24.94 ± 5.37 MPa). The highest hardness was recorded in Group F (23.29 ± 0.8 HV) and the lowest value was in Group A (15.88 ± 1.02 HV). CONCLUSION: The modification of PMMA with NPs with proven antimicrobial activity can increase the flexural strength and hardness of the material. GO, TiO2 and, GOCUR NPs were each used alone and in different combinations, and all the groups displayed higher flexural strength and hardness than the unmodified PMMA.

EMPLOYING ANTIMICROBIAL NANOPARTICLES TO REDUCE ORAL BIOFILMS

Oral biofilm is a major problem in almost all individuals as they cause dysbiosis of the oral cavity and lead to various microbial infections and related ailments. Currently, antibiotics and antifungal drugs are the major way to control oral biofilm, but the rapid increase in antibiotic-resistant bacterial strains has limited the treatment options and increased the virulence factors of these bacteria. With the inception of nanotechnology, metals such as gold, silver, copper and titanium can be converted to nanoparticles, which are target-oriented particles with enhanced therapeutic values and antimicrobial efficacy with minimum side effects. The application of nanoparticles in antimicrobial drugs increases in potential, as a function of their biocidal, anti-adhesive, and delivery capabilities, shows much potential.

Design of Zn1-xCuxO Nanocomposite Ag-doped As An Efficient Antibacterial Agent

This study aims at the preparation of antimicrobial nanoparticles hybrid based on silver (Ag) doped Zn1-xCuxO. Zn1-xCuxO nanocomposite Ag-doped prepared via wet chemical route, co-precipitation, and impregnation method, respectively. The inclusion of silver in the nanocomposite did not change its structure. However, the insertion of CuO into the ZnO structure has no impact due to the similarity of Cu ion radius with Zn ion radius (0.74 toward 0.73 Å). Hybrid nanomaterials characterized by XRD, FT-IR, and FESEM technique. The effect of loading of CuO nanoparticles into ZnO nanomaterials investigated on their antimicrobial behavior. For this purpose, CuO with a variety ratio doped on the ZnO nanoparticles, and then Ag entrapped by impregnation methods. Minimum inhibitory concentration (MIC) measurements were carried out to measure the antimicrobial behavior of ZnO(Ag) and mixed hybrid Zn1-xCuxO(Ag) towards gram-negative and gram-positive bacteria and fungus. gram-positive and gram-negative bacteria were generally more sensitive to ZnO and CuO nanoparticles, respectively. Then, these hybrid nanomaterials can be an excellent candidate for both gram-positive and gram-negative bacteria.

Nanomaterials can inhibit planktonic and biofilm bacteria and can be used as topical therapy for mouth and wound-related infections

Nanomaterials are an emerging therapeutic option for resistant planktonic MDR and biofilm diseases. The adjustable properties of nanomaterials, especially their surface functionalities, give design opportunities that can be fine-tuned to maximize therapeutic effectiveness while lowering host toxicity. This review shows how nanoparticles can attack bacteria in both planktonic and biofilm forms. Nanomaterials can access new multimodal antibacterial pathways, lowering or avoiding antibiotic resistance. Nanoparticles can be employed as topical treatments for mouth and wound biofilm-related infections. Strategies combining bactericidal effects with biofilm dispersion, however, are best for total biofilm eradication. Stimulated nanoparticles that take advantage of particular microenvironments at infection sites, such as pH and pathogen-derived metabolites, are one of numerous strategies to target nanomaterial MDR bacteria. Nanoparticles' long-term effects on the body and their systemic safety remain important challenges to therapeutic use. Nanoparticles' pharmacokinetic profile is presently being defined to better comprehend their bodily destiny. Effective antimicrobial nanomaterials need interdisciplinary collaboration between chemists, biological researchers (including microbiologists), and engineers. Cooperation across basic, translational, and industrial groups will be important in delivering antimicrobial nanoparticles to the clinic. Overall, nanomaterial-based treatment approaches offer a feasible alternative to antibiotics for difficult-to-treat diseases, alleviating post-antibiotic issues.

Exploitation of Antimicrobial Nanoparticles and Their Applications in Biomedical Engineering

Antibiotic resistance is a major threat to public health, which contributes largely to increased mortality rates and costs in hospitals. The severity and widespread nature of antibiotic resistance result in limited treatments to effectively combat antibiotic-resistant pathogens. Nanoparticles have different or enhanced properties in contrast to their bulk material, including antimicrobial efficacy towards a broad range of microorganisms. Their beneficial properties can be utilised in various bioengineering technologies. Thus, antimicrobial nanoparticles may provide an alternative to challenge antibiotic resistance. Currently, nanoparticles have been incorporated into materials, such as fibres, glass and paints. However, more research is required to elucidate the mechanisms of action fully and to advance biomedical applications further. This paper reviews the antimicrobial efficacies and the intrinsic properties of different metallic nanoparticles, their potential mechanisms of action against certain types of harmful pathogens and how these properties may be utilised in biomedical and healthcare products with the aim to reduce cross contaminations, disease transmissions and usage of antibiotics.

Strategies to Use Nanofiber Scaffolds as Enzyme-Based Biocatalysts in Tissue Engineering Applications

Nanofibers are considered versatile materials with remarkable potential in tissue engineering and regeneration. In addition to their extracellular matrix-mimicking properties, nanofibers can be functionalized with specific moieties (e.g., antimicrobial nanoparticles, ceramics, bioactive proteins, etc.) to improve their overall performance. A novel approach in this regard is the use of enzymes immobilized onto nanofibers to impart biocatalytic activity. These nanofibers are capable of carrying out the catalysis of various biological processes that are essential in the healing process of tissue. In this review, we emphasize the use of biocatalytic nanofibers in various tissue regeneration applications. Biocatalytic nanofibers can be used for wound edge or scar matrix digestion, which reduces the hindrance for cell migration and proliferation, hence displaying applications in fast tissue repair, e.g., spinal cord injury. These nanofibers have potential applications in bone regeneration, mediating osteogenic differentiation, biomineralization, and matrix formation through direct enzyme activity. Moreover, enzymes can be used to undertake efficient crosslinking and fabrication of nanofibers with better physicochemical properties and tissue regeneration potential.

Synthesis and self-assembly of curcumin-modified amphiphilic polymeric micelles with antibacterial activity

Background The ubiquitous nature of bacterial biofilms combined with the enhanced resistance towards antimicrobials has led to the development of an increasing number of strategies for biofilm eradication. Such strategies must take into account the existence of extracellular polymeric substances, which obstruct the diffusion of antibiofilm agents and assists in the maintenance of a well-defended microbial community. Within this context, nanoparticles have been studied for their drug delivery efficacy and easily customised surface. Nevertheless, there usually is a requirement for nanocarriers to be used in association with an antimicrobial agent; the intrinsically antimicrobial nanoparticles are most often made of metals or metal oxides, which is not ideal from ecological and biomedical perspectives. Based on this, the use of polymeric micelles as nanocarriers is appealing as they can be easily prepared using biodegradable organic materials. Results In the present work, micelles comprised of poly(lactic-co-glycolic acid) and dextran are prepared and then functionalised with curcumin. The effect of the functionalisation in the micelle’s physical properties was elucidated, and the antibacterial and antibiofilm activities were assessed for the prepared polymeric nanoparticles against Pseudomonas spp. cells and biofilms. It was found that the nanoparticles have good penetration into the biofilms, which resulted in enhanced antibacterial activity of the conjugated micelles when compared to free curcumin. Furthermore, the curcumin-functionalised micelles were efficient at disrupting mature biofilms and demonstrated antibacterial activity towards biofilm-embedded cells. Conclusion Curcumin-functionalised poly(lactic-co-glycolic acid)-dextran micelles are novel nanostructures with an intrinsic antibacterial activity tested against two Pseudomonas spp. strains that have the potential to be further exploited to deliver a secondary bioactive molecule within its core. Graphic Abstract