The role of nanomaterials and antibiotics in microbial resistance and environmental impact: an overview

Eco-friendly moxifloxacin removal using date seed waste and Ni-Fe LDH: Adsorption efficiency and antimicrobial potential

BACKGROUND

New pharmacological remediation techniques were needed due to their detrimental impacts on human health and aquatic ecosystems. Layer double hydroxide (LDH) can be made inexpensively and readily available using easy preparation techniques. Three nanomaterials date seed powder (DSP), Ni-Fe LDH, and Ni-Fe LDH/(DSP) composite are used to eliminate Moxifloxacin (MOX).

OBJECTIVE

Providing the date seed powder (DSP), Ni-Fe LDH, and Ni-Fe LDH/(DSP) composite multifunction as an ecofriendly adsorbents for antibiotic residues also its assessing antibacterial effectiveness in addition to other fungal organisms.

METHODS

The catalysts were synthesized via co-precipitation and characterized using HRTEM, FESEM, FT-IR, X-ray, PZC and BET analyses. Adsorption experiments were conducted to evaluate the effects of pH, adsorbent dose, and contact time, while kinetic and isotherm models were employed to elucidate the adsorption mechanisms. Minimum Inhibitory Concentration (MIC), Minimum Fungicidal Concentration (MFC), Minimum Bactericidal Concentration (MBC), and Disc Diffusion assays for bacterial activity were applied for antifungal study.

RESULTS

The removal percent of the MOX was 35.37 % at pH 3, 44.91 % at pH 7, and 83.50 % at pH 5 for (DSP), Ni-Fe LDH and Ni-Fe LDH /(DSP) composite, respectively. The Langmuir- Freundlich model is the best suitable model for three nanomaterials (DSP), Ni-Fe LDH and Ni-Fe LDH /(DSP), R2 were (0.97,0.99 and 0.99, respectively) and qmax were (212.77, 206.7 and 251,6 respectively).

CONCLUSION

current research indicates that the Ni-Fe LDH/(DSP) composite is a promising nanomaterial for treating wastewater and has a greater antimicrobial efficacy than each alone against both bacterial and fungal pathogens.

Novel nanomaterials-based combating strategies against drug-resistant bacteria

Numerous types of contemporary antibiotic treatment regimens have become ineffective with the increasing incidence of drug tolerance. As a result, it is pertinent to seek novel and innovative solutions such as antibacterial nanomaterials (NMs) for the prohibition and treatment of hazardous microbial infections. Unlike traditional antibiotics (e.g., penicillin and tetracycline), the unique physicochemical characteristics (e.g., size dependency) of NMs endow them with bacteriostatic and bactericidal potential. However, it is yet difficult to mechanistically predict or decipher the networks of molecular interaction (e.g., between NMs and the biological systems) and the subsequent immune responses. In light of such research gap, this review outlines various mechanisms accountable for the inception of drug tolerance in bacteria. It also delineates the primary factors governing the NMs-induced molecular mechanisms against microbes, specifically drug-resistant bacteria along with the various NM-based mechanisms of antibacterial activity. The review also explores future directions and prospects for NMs in combating drug-resistant bacteria, while addressing challenges to their commercial viability within the healthcare industry.

Effects of coexisting nanomaterials on the photodegradation behavior and ecotoxicity of antibiotics in the aqueous

Nanomaterials (NPs) and antibiotics, as two emergent pollutants, forms a complex contamination through their interaction, potentially causing adverse effects on the organism. This study systematically examined the influence of two NPs (CuO NPs and carbon nanotubes, CNTs) on the photodegradation behavior of tetracycline (TC) and their combined toxic effects on Chlorella vulgaris. The results showed that CuO NPs significantly accelerated TC photodegradation compared to CNTs, increasing the TC photodegradation rate constant by187.6%. Electron spin resonance (ESR) indicated that under the coexistence of CuO NPs or CNTs, 1O2、O2•- and •OH were the main active species promoting TC photodegradation. Probe and quenching experiments confirmed the predominant role of O2•- and 1O2 in the presence of CuO NPs and CNTs. Additionally, three possible TC photodegradation pathways were proposed for the coexistence of CuO NPs and CNTs. In the Chlorella vulgaris growth inhibition experiment, the combined toxicity of CuO NPs or CNTs and TC was higher than that of individual substance, indicating significant synergistic effects, especially with the combination of CNTs and TC. This study provides a new perspective on accurately assessing the environmental behaviors and risks when NPs and antibiotics coexist.

Innovative Biomedical and Technological Strategies for the Control of Bacterial Growth and Infections

Antibiotics comprise one of the most successful groups of pharmaceutical products. Still, they have been associated with developing bacterial resistance, which has become one of the most severe problems threatening human health today. This context has prompted the development of new antibiotics or co-treatments using innovative tools to reverse the resistance context, combat infections, and offer promising antibacterial therapy. For the development of new alternatives, strategies, and/or antibiotics for controlling bacterial growth, it is necessary to know the target bacteria, their classification, morphological characteristics, the antibiotics currently used for therapies, and their respective mechanisms of action. In this regard, genomics, through the sequencing of bacterial genomes, has generated information on diverse genetic resources, aiding in the discovery of new molecules or antibiotic compounds. Nanotechnology has been applied to propose new antimicrobials, revitalize existing drug options, and use strategic encapsulating agents with their biochemical characteristics, making them more effective against various bacteria. Advanced knowledge in bacterial sequencing contributes to the construction of databases, resulting in advances in bioinformatics and the development of new antimicrobials. Moreover, it enables in silico antimicrobial susceptibility testing without the need to cultivate the pathogen, reducing costs and time. This review presents new antibiotics and biomedical and technological innovations studied in recent years to develop or improve natural or synthetic antimicrobial agents to reduce bacterial growth, promote well-being, and benefit users.

Biofilm-responsive encapsulated-phage coating for autonomous biofouling mitigation in water storage systems

Biofilms in water storage systems may harbor pathogens that threaten public health. Chemical disinfectants are marginally effective in eradicating biofilms due to limited penetration, and often generate harmful disinfection byproducts. To enhance biofouling mitigation in household water storage tanks, we encapsulated bacteriophages (phages) in chitosan crosslinked with tri-polyphosphate and 3-glycidoxypropyltrimethoxysilane. Phages served as self-propagating green biocides that exclusively infect bacteria. This pH-responsive encapsulation (244 ± 11 nm) enabled autonomous release of phages in response to acidic pH associated with biofilms (corroborated by confocal microscopy with pH-indicator dye SNARF-4F), but otherwise remained stable in pH-neutral tap water for one month. Encapsulated phages instantly bind to plasma-treated plastic and fiberglass surfaces, providing a facile coating method that protects surfaces highly vulnerable to biofouling. Biofilm formation assays were conducted in tap water amended with 200 mg/L glucose to accelerate growth and attachment of Pseudomonas aeruginosa, an opportunistic pathogen commonly associated with biofilms in drinking water distribution and storage systems. Biofilms formation on plastic surfaces coated with encapsulated phages decreased to only 6.7 ± 0.2% (on a biomass basis) relative to the uncoated controls. Likewise, biofilm surface area coverage (4.8 ± 0.2 log CFU/mm²) and live/dead fluorescence ratio (1.80) were also lower than the controls (6.6 ± 0.2 log CFU/mm² and live/dead ratio of 11.05). Overall, this study offers proof-of-concept of a chemical-free, easily implementable approach to control problematic biofilm-dwelling bacteria and highlights benefits of this bottom-up biofouling control approach that obviates the challenge of poor biofilm penetration by biocides.

Antibiofilm Synergistic Activity of Streptomycin in Combination with Thymol-Loaded Poly (Lactic-co-glycolic Acid) Nanoparticles against Klebsiella pneumoniae Isolates

Background. Thymol is an important component of essential oils found in the oil of thyme, is extracted mainly from Thymus vulgaris, and was shown to act synergistically with streptomycin against Klebsiella pneumoniae biofilms. Additionally, thymol could be encapsulated into poly (lactic-co-glycolic acid) (PLGA) nanoparticles to overcome issues related to its low water solubility and high volatility. The present study aimed to investigate the antibiofilm activity of thymol-loaded PLGA nanoparticles (Thy-NPs) alone and in combination with streptomycin against biofilms of K. pneumoniae isolates. Methods. The broth microdilution method was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The antibiofilm activities were determined by the safranin dye assay. The synergistic effect of Thy-NPs with streptomycin was assessed by the checkerboard method. The kinetic study of the biofilm biomass and time-kill assay were further performed. Results. Thy-NPs exhibited the highest antibacterial activity against K. pneumoniae isolates, with MIC values ranging from 1 to 8 µg/mL. Additionally, Thy-NPs showed the highest antibiofilm activity against K. pneumoniae isolates with minimal biofilm inhibitory concentration (MBIC) and minimal biofilm eradication concentration (MBEC) values ranging from 16 to 64 µg/mL and from 32 to 128 µg/Ml, respectively. The combination treatment combining Thy-NPs with streptomycin showed a synergistic effect against the inhibition of biofilm formation and eradication of biofilms of K. pneumoniae isolates with fractional inhibitory concentration index values ranging from 0.13 to 0.28. In addition, the MBIC and MBEC values of streptomycin against K. pneumoniae isolates were dramatically reduced (up to 128-fold) in combination with Thy-NPs, suggesting that Thy-NPs would enhance the antibiofilm activity of streptomycin. The biomass and time-kill kinetics analysis confirmed the observed synergistic interactions and showed the bactericidal activity of streptomycin in combination with Thy-NPs. Conclusions. Our results indicate that the synergistic bactericidal effect between streptomycin and Thy-NPs could be a promising approach in the control of biofilm-associated infections caused by K. pneumoniae.