The discovery of antibiotics was hailed as a historic breakthrough for the human race in the fight against bacterial and malignant infections. However, in a very short time, owing to their acute and aggressive nature, bacteria have developed resistance against antibiotics and other chemotherapeutics agents. Potentially, this situation could again result in bacterial infection outbreaks. Metal and metal oxide nanoparticles have been proven as better alternatives; the combination of antibiotics and metal oxide nanoparticles was shown to decrease the toxicity and enhance the antibacterial, antiviral, and anticancer efficacy of the agents. This review provides a detailed view about the role of metal and metal oxide nanoparticles in the treatment of infections in conjunction with antibiotics, their modes of action, and synergism. In addition, the problems of multidrug resistance are addressed and will allow the development of a comprehensive, reliable, and rational treatment plan. It is expected that this comprehensive review will lead to new research opportunities, which should be helpful for future applications in biomedical science.

The aim of the current investigation was to determine the antibacterial and antibiofilm potential of MgO nanoparticles (NPs) against antibiotic‐resistant clinical strains of bacteria. MgO NPs were synthesized by a wet chemical method and further characterized by scanning electron microscopy and energy dispersive X‐ray. Antibacterial activity was determined by broth microdilution and agar diffusion methods. The Bradford method was used to assess cellular protein leakage as a result of loss of membrane integrity. Microtiter plate assay following crystal violet staining was employed to determine the effect of MgO NPs on biofilm formation and removal of established biofilms. MIC values ranged between 125 and 500 μg/mL. Moreover, treatment with MgO NPs accelerated rate of membrane disruption, measured as a function of leakage of cellular proteins. Leakage of cellular protein content was greater among gram‐negative bacteria. Cell adherence assay indicated 25.3–49.8% inhibition of bacterial attachment to plastic surfaces. According to a static biofilm method, MgO NPs reduced biofilm formation potential from 31% to 82.9% in a time‐dependent manner. Moreover, NPs also significantly reduced the biomass of 48, 72, 96 and 120 hr old biofilms (P < 0.05). Cytotoxicity experiments using a neutral red assay revealed that MgO NPs are non‐toxic to HeLa cells at concentrations of 15–120 μg/mL. These data provide in vitro scientific evidence that MgO NPs are effective and safe antibiofilm agents that inhibit adhesion, biofilm formation and removal of established biofilms of multidrug‐resistant bacteria.

Phytonanotechnology plays a crucial part in the production of good quality and high-yield food. It can also alter the plant's production systems, hence permitting the efficient, controlled and stable release of agrochemicals such as fertilizers and pesticides. An advanced understanding of nanomaterials interaction with plant responses like localization and uptake, etc. could transfigure the production of crops with high disease resistance and efficient nutrients utilization. In agriculture, the use of nanomaterials has gained acceptance due to their wide-range applications. However, their toxicity and bioavailability are the major hurdles for their massive employment. Undoubtedly, nanoparticles positively influence seeds germination, growth and development, stress management and post-harvest handling of vegetables and fruits. These nanoparticles may also cause toxicity in plants through oxidative stress by generation of excessive reactive oxygen species thus affecting the cellular biomolecules and targeting different channels. Nanoparticles have shown to exert various effects on plants that are mainly affected by various attributes such as physicochemical features of nanomaterials, coating materials for nanoparticles, type of plant, growth stages and growth medium for plants. This article discusses the interaction, accretion and toxicity of nanomaterials in plants. The factors inducing nanotoxicity and the mechanisms followed by nanomaterials causing toxicity are also instructed. At the end, detoxification mechanism of plant is also presented.

The delayed healing of wounds among people with diabetes is a severe problem worldwide. Hyperglycemia and increased levels of free radicals are the major inhibiting factors of wound healing in diabetic patients. Plant extracts are a rich source of polyphenols, allowing them to be an effective agent for wound healing. Drying temperature and extraction solvent highly affect the stability of polyphenols in plant materials. However, there is a need to optimize the extraction protocol to ensure the efficacy of the final product. For this purpose, the effects of drying temperature and solvents on the polyphenolic composition and diabetic wound healing activity of Moringa oleifera leaves were examined in the present research. Fresh leaves were oven dried at different temperatures (10 °C, 30 °C, 50 °C, and 100 °C) and extracted in three solvents (acetone, ethanol, and methanol) to obtain twelve extracts in total. The extracts were assessed for free radical scavenging and antihyperglycemic effects using DPPH (2,2-diphenylpicrylhydrazyl) and α- glucosidase inhibition assays. Alongside this, a scratch assay was performed to evaluate the cell migration activity of M. oleifera on the human retinal pigment epithelial cell line. The cytotoxicity of the plant extracts was assessed on human retinal pigment epithelial (RPE) and hepatocellular carcinoma (Huh-7) cell lines. Using high-performance liquid chromatography, phenolic compounds in extracts of M. oleifera were identified. We found that an ethanol-based extract prepared by drying the leaves at 10 °C contained the highest amounts of identified polyphenols. Moringa oleifera extracts showed remarkable antioxidant, antidiabetic, and cell migration properties. The best results were obtained with leaves dried at 10 °C and 30 °C. Decreased activities were observed with drying temperatures of 50 °C and above. Moreover, M. oleifera extracts exhibited no toxicity on RPE cells, and the same extracts were cytotoxic for Huh-7 cells. This study revealed that M. oleifera leaves extracts can enhance wound healing in diabetic conditions due to their antihyperglycemic, antioxidant, and cell migration effects. The leaves of this plant can be an excellent therapeutic option when extracted at optimum conditions.

Acinetobacter baumannii is a biofilm forming multidrug resistant (MDR) pathogen responsible for respiratory tract infections. In this study, aluminium oxide nanoparticles (Al₂O₃ NPs) were synthesized and characterized by TEM and EDX and shown to be spherical shaped nanoparticles with a diameter < 10 nm. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) for the Al₂O₃ NPs ranged between 125 and 1,000 µg ml⁻¹. Exposure to NPs caused cellular membrane disruption, indicated by an increase in cellular leakage of the contents. Biofilm inhibition was 11.64 to 70.2%, whereas attachment of bacteria to polystyrene surfaces was reduced to 48.8 to 51.9% in the presence of NPs. Nanoparticles also reduced extracellular polymeric substance production and the biomass of established biofilms. The data revealed the non-toxic nature of Al₂O₃ NPs up to a concentrations of 120 µg ml⁻¹ in HeLa cell lines. These results demonstrate an effective and safer use of Al₂O₃ NPs against the MDR A. baumannii by targeting biofilm formation, adhesion and EPS production.

Plant growth enhancement using plant beneficial bacteria has been viewed in the sustainable agriculture as an alternative to chemical fertilizers. Actinobacteria, among the group of important plant-associated bacteria, have been widely studied for its plant growth promotion activities. Actinobacteria are considered as a limelight among agriculturists for their beneficial aspects toward plants. They are naturally occurring spore-forming bacteria inhabiting the soil and known for their plant growth-promoting and biocontrol properties. The mechanisms behind these activities include nitrogen fixation, phosphate solubilization, siderophore production, and other attributes such as antifungal production of metabolites, phytohormones, and volatile organic compound. All these activities not only enhance the plant growth but also provide resistance in plants to withstand unfavorable conditions of the environment. Hence, this chapter emphasizes on the plant growth traits of actinobacteria and how far it was studied for enhanced growth and bio-fortification.