Shape-Dependent Biomimetic Inhibition of Enzyme by Nanoparticles and Their Antibacterial Activity

Current advances in black phosphorus-based antibacterial nanoplatform for infection therpy

Black phosphorus (BP) has attracted much attention due to its excellent physiochemical properties. However, due to its biodegradability and simple antibacterial mechanism, using only BP nanomaterials to combat bacterial infections caused by drug-resistant pathogens remains a significant challenge. In order to improve the antibacterial efficiency and avoid the emergence of drug resistance, BP nanomaterials have been combined with other functional materials to form black phosphorus-based antibacterial nanoplatform (BPANP), which provides unprecedented opportunities for the treatment of drug-resistant infections. This article reviews the performance of BPANP and its multiple antibacterial mechanisms while emphatically introducing its design direction and latest application progress in antibacterial fields. Moreover, this paper additionally summarizes and discusses the current challenges and inadequacies of BPANP that need to be improved in future research. We believe that this review will provide researchers with an up-to-date and multifaceted reference, and provide new ideas for designing effective strategies against drug-resistant bacteria.

Biosynthesis of iron oxide nanoparticles using plant extracts and evaluation of their antibacterial activity

The biosynthesis of iron oxide nanoparticles has received increasing attention in the field of food nanotechnology because of their non-toxicity, high efficiency, high antibacterial power, and decontamination features. Therefore, biosynthesis of iron oxide nanoparticles (nFe) was prepared from the leaves of some vegetables, such as cabbage (C) and turnips (T), as well as moringa leaves (M). Alcoholic extracts of these nanoparticles were also tested on Staphylococcus aureus and Escherichia coli to evaluate their antibacterial activity. The results revealed that the particle sizes of the biosynthesis nanomaterials studied ranged from 12.99 to 22.72 nm, and the particles were spherical, irregular, and surrounded by black color. It also contains many functional groups and minerals. Iron nanoparticles modified with Moringa oleifera extract at a concentration of 200 ppm had the highest phenol content compared to other biosynthesis nanoparticles studied. TnFe and MnFe at 200 ppm had a maximum zone of inhibition of 25 mm and 24 mm against Staphylococcus aureus and Escherichia coli, respectively. While the minimum inhibition zone of 8.0 mm was observed at 25 ppm for nFe against Escherichia coli. Therefore, it is recommended to use these extracts of biosynthesis iron oxide nanoparticles as antibacterial agents for stored foods.

Influence of Physicochemical Properties of Iron Oxide Nanoparticles on Their Antibacterial Activity

The increasing occurrence of infectious diseases caused by antimicrobial resistance organisms urged the necessity to develop more potent, selective, and safe antimicrobial agents. The unique magnetic and tunable properties of iron oxide nanoparticles (IONPs) make them a promising candidate for different theragnostic applications, including antimicrobial agents. Though IONPs act as a nonspecific antimicrobial agent, their antimicrobial activities are directly or indirectly linked with their synthesis methods, synthesizing precursors, size, shapes, concentration, and surface modifications. Alteration of these parameters could accelerate or decelerate the production of reactive oxygen species (ROS). An increase in ROS role production disrupts bacterial cell walls, cell membranes, alters major biomolecules (e.g., lipids, proteins, nucleic acids), and affects metabolic processes (e.g., Krebs cycle, fatty acid synthesis, ATP synthesis, glycolysis, and mitophagy). In this review, we will investigate the antibacterial activity of bare and surface-modified IONPs and the influence of physiochemical parameters on their antibacterial activity. Additionally, we will report the potential mechanism of IONPs' action in driving this antimicrobial activity.

Compartmentalization into Outer and Inner Shells of Hollow Nanospheres for Antibiosis Based on Chemistry and Physical Damages

There is a substantially ascending demand for nonantibiotic strategies to overcome the resistance of bacterial infections. Here, the discovery of a distinctive antibacterial structure is reported. The novel structure of nanoparticle strategy is proposed for appreciable bacteria killing by the smart design of the delayed addition of crosslinkers into the reaction mixture. [2-(methacryloyloxy)ethyl]trimethylammonium chloride solution (MTCl), a water-soluble ionic liquid (IL), has narrow-size material distribution, good whiteness, and high weather resistance. The quaternary ammonium salt is utilized to efficiently permeate cell membranes through electrostatic interaction, accordingly, boasting a beneficiary of antibacterial properties. More importantly, it allows bacteria to attach the nanomaterials easily, especially the double-shelled nanosphere. In light of the introduction of 9-amino(9-deoxy)ep-quinine (QNNH2) on its inner shell, it blocks the nucleic acid and glucose metabolism in bacteria, which is betterment of the antibacterial activity of double-shelled structure nanoparticle compared to other structure of nanomaterials. This physical/chemical/biological triple antibacterial process eliminates the need for traditional antibiotics, and the fabrication strategies and material properties described here provide insights into the design of antibacterial nanomaterials based on chemical and physical effects.

Nanoenzymes: A Radiant Hope for the Early Diagnosis and Effective Treatment of Breast and Ovarian Cancers

Breast and ovarian cancers, despite having chemotherapy and surgical treatment, still have the lowest survival rate. Experimental stages using nanoenzymes/nanozymes for ovarian cancer diagnosis and treatment are being carried out, and correspondingly the current treatment approaches to treat breast cancer have a lot of adverse side effects, which is the reason why researchers and scientists are looking for new strategies with less side effects. Nanoenzymes have intrinsic enzyme-like activities and can reduce the shortcomings of naturally occurring enzymes due to the ease of storage, high stability, less expensive, and enhanced efficiency. In this review, we have discussed various ways in which nanoenzymes are being used to diagnose and treat breast and ovarian cancer. For breast cancer, nanoenzymes and their multi-enzymatic properties can control the level of reactive oxygen species (ROS) in cells or tissues, for example, oxidase (OXD) and peroxidase (POD) activity can be used to generate ROS, while catalase (CAT) or superoxide dismutase (SOD) activity can scavenge ROS. In the case of ovarian cancer, most commonly nanoceria is being investigated, and also when folic acid is combined with nanoceria there are additional advantages like inhibition of beta galactosidase. Nanocarriers are also used to deliver small interfering RNA that are effective in cancer treatment. Studies have shown that iron oxide nanoparticles are actively being used for drug delivery, similarly ferritin carriers are used for the delivery of nanozymes. Hypoxia is a major factor in ovarian cancer, therefore MnO2-based nanozymes are being used as a therapy. For cancer diagnosis and screening, nanozymes are being used in sonodynamic cancer therapy for cancer diagnosis and screening, whereas biomedical imaging and folic acid gold particles are also being used for image guided treatments. Nanozyme biosensors have been developed to detect ovarian cancer. This review article summarizes a detailed insight into breast and ovarian cancers in light of nanozymes-based diagnostic and therapeutic approaches.

Rationally Designed Functionalization of Single-Walled Carbon Nanotubes for Real-Time Monitoring of Cholinesterase Activity and Inhibition in Plasma

Enzymes play a pivotal role in regulating numerous bodily functions. Thus, there is a growing need for developing sensors enabling real-time monitoring of enzymatic activity and inhibition. The activity and inhibition of cholinesterase (CHE) enzymes in blood plasma are fluorometrically monitored using near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) as probes, strategically functionalized with myristoylcholine (MC)- the substrate of CHE. A significant decrease in the fluorescence intensity of MC-suspended SWCNTs upon interaction with CHE is observed, attributed to the hydrolysis of the MC corona phase of the SWCNTs by CHE. Complementary measurements for quantifying choline, the product of MC hydrolysis, reveal a correlation between the fluorescence intensity decrease and the amount of released choline, rendering the SWCNTs optical sensors with real-time feedback in the NIR biologically transparent spectral range. Moreover, when synthetic and naturally abundant inhibitors inhibit the CHE enzymes present in blood plasma, no significant modulations of the MC-SWCNT fluorescence are observed, allowing effective detection of CHE inhibition. The rationally designed SWCNT sensors platform for monitoring of enzymatic activity and inhibition in clinically relevant samples is envisioned to not only advance the field of clinical diagnostics but also deepen further understanding of enzyme-related processes in complex biological fluids.

Synthetic Polymer Nanoparticles as an Abiotic Artificial Inhibitor of Tyrosinase

An innovative methodology is presented for synthesizing synthetic polymer nanoparticles (TINPs) as potent tyrosinase inhibitors. This inhibition strategy combines the integration of two distinct functionalities, phenol, and phenylboronic acid, within the TINPs structure. The phenyl group mimics the natural monophenol substrate, forming a strong coordination with the catalytic copper ion, significantly inhibiting tyrosinase activity. Additionally, phenylboronic acid interacts with catechol, another tyrosinase substrate, further reducing enzyme efficiency. The shared benzene ring in phenyl and phenylboronic acid enhances binding to tyrosinase's hydrophobic pocket near its copper active site, contributing to potent inhibition. TINPs exhibit exceptional performance, boasting an impressive IC50 value of 3.5×10-8 m and an inhibition constant of 9.8×10-9 m. Validation of the approach is unequivocally demonstrated through the successful inhibition of tyrosinase activity and melanin production, substantiated in both in vitro and in vivo scenarios. The mechanism of TINP inhibition is elucidated through circular dichroism and Fourier transform infrared spectroscopy. This study introduces a versatile design approach for developing abiotic polymer-based enzyme inhibitors, expanding possibilities in enzyme inhibition research.

Tapered chiral nanoparticles as broad-spectrum thermally stable antivirals for SARS-CoV-2 variants

The incessant mutations of viruses, variable immune responses, and likely emergence of new viral threats necessitate multiple approaches to novel antiviral therapeutics. Furthermore, the new antiviral agents should have broad-spectrum activity and be environmentally stable. Here, we show that biocompatible tapered CuS nanoparticles (NPs) efficiently agglutinate coronaviruses with binding affinity dependent on the chirality of surface ligands and particle shape. L-penicillamine-stabilized NPs with left-handed curved apexes display half-maximal inhibitory concentrations (IC50) as low as 0.66 pM (1.4 ng/mL) and 0.57 pM (1.2 ng/mL) for pseudo-type SARS-CoV-2 viruses and wild-type Wuhan-1 SARS-CoV-2 viruses, respectively, which are about 1,100 times lower than those for antibodies (0.73 nM). Benefiting from strong NPs-protein interactions, the same particles are also effective against other strains of coronaviruses, such as HCoV-HKU1, HCoV-OC43, HCoV-NL63, and SARS-CoV-2 Omicron variants with IC50 values below 10 pM (21.8 ng/mL). Considering rapid response to outbreaks, exposure to elevated temperatures causes no change in the antiviral activity of NPs while antibodies are completely deactivated. Testing in mice indicates that the chirality-optimized NPs can serve as thermally stable analogs of antiviral biologics complementing the current spectrum of treatments.

Versatility of copper-iron bimetallic nanoparticles fabricated using Hibiscus rosa-sinensis flower phytochemicals: various enzymes inhibition, antibiofilm effect, chromium reduction and dyes removal

Bimetallic nanoparticles (NPs) are considered superior in terms of stability and function with respect to its monometallic counterparts. Hence, in the present study Hibiscus rosa-sinensis flower extract was used to synthesis copper-iron bimetallic nanoparticles (HF-FCNPs). HF-FCNPs was characterized and its applications (biological and environmental) were determined. HF-FCNPs were spherical in shape with high percentage of copper inducted into the NPs. HF-FCNPs inhibited mammalian glucosidases [maltase (IC50: 548.71 ± 61.01 µg/mL), sucrase (IC50: 441.34 ± 36.03 µg/mL), isomaltase (IC50: 466.37 ± 27.09 µg/mL) and glucoamylase (IC50: 403.12 ± 14.03 µg/mL)], alpha-amylase (IC50: 16.27 ± 1.73 µg/mL) and acetylcholinesterase [AChE (IC50: 0.032 ± 0.004 µg/mL)] activities. HF-FCNPs showed competitive inhibition against AChE, maltase and sucrase activities; mixed inhibition against isomaltase and glucoamylase activities; whereas non-competitive inhibition against α-amylase activity. HF-FCNPs showed zone of inhibition of 16 ± 2 mm against S. mutans at 100 µg/mL concentration. HF-FCNPs inhibited biofilm formation of dental pathogen, S. mutans. SEM and confocal microscopy analysis revealed the disruption of network formation and bacterial cell death induced by HF-FCNPs treatment on tooth model of S. mutans biofilm. HF-FCNPs efficiently removed hexavalent chromium in pH-independent manner and followed first order kinetics. Through Langmuir isotherm fit the qmax (maximum adsorption capacity) was determined to be 62.5 mg/g. Further, HF-FCNPs removed both anionic and cationic dyes. Altogether, facile synthesis of HF-FCNPs was accomplished and its biological (enzyme inhibition and antibiofilm activity) and environmental (catalyst to remove pollutants) applications have been understood.

In the View of Electrons Transfer and Energy Conversion: The Antimicrobial Activity and Cytotoxicity of Metal-Based Nanomaterials and Their Applications

The global pandemic and excessive use of antibiotics have raised concerns about environmental health, and efforts are being made to develop alternative bactericidal agents for disinfection. Metal-based nanomaterials and their derivatives have emerged as promising candidates for antibacterial agents due to their broad-spectrum antibacterial activity, environmental friendliness, and excellent biocompatibility. However, the reported antibacterial mechanisms of these materials are complex and lack a comprehensive understanding from a coherent perspective. To address this issue, a new perspective is proposed in this review to demonstrate the toxic mechanisms and antibacterial activities of metal-based nanomaterials in terms of energy conversion and electron transfer. First, the antimicrobial mechanisms of different metal-based nanomaterials are discussed, and advanced research progresses are summarized. Then, the biological intelligence applications of these materials, such as biomedical implants, stimuli-responsive electronic devices, and biological monitoring, are concluded based on trappable electrical signals from electron transfer. Finally, current improvement strategies, future challenges, and possible resolutions are outlined to provide new insights into understanding the antimicrobial behaviors of metal-based materials and offer valuable inspiration and instructional suggestions for building future intelligent environmental health.

Metal nanoparticles as inhibitors of enzymes and toxins of multidrug-resistant Staphylococcus aureus

Staphylococcus aureus is an aerobic Gram-positive spherical bacterium known to cause a broad range of infections worldwide. It is a major cause of infective skin and soft infections and severe and life-threatening conditions, such as pneumonia, bloodstream infections, and endocarditis. The emergence of drug-resistant strains of S aureus, particularly methicillin-resistant S aureus (MRSA), has become a significant concern in the healthcare community. Antibiotic-resistant S aureus is commonly acquired in hospitals and long-term care facilities. It often affects patients with weakened immune systems, those undergoing invasive medical procedures, or those who have been hospitalized for extended periods. In the US, S aureus is known to cause potentially fatal illnesses, such as toxic shock syndrome (TSS) and acute-onset toxic shock syndrome (TSS), which are characterized by fever and hypotension. It develops resistance to antibiotics through several mechanisms, such as the production of enzymes that inactivate antibiotics, target site modification, efflux pumps, and plasmid-mediated resistance. Therefore, preventing the spread of drug-resistant S aureus is needed, and there is an urgent need to explore novel approaches in the development of anti-staphylococcal agents. This article reviews the principal infections caused by S aureus, major virulence factors, mechanisms of resistance development, and nanotechnology-based solutions for the control of drug-resistant S aureus.

Mixed and non-competitive enzyme inhibition: underlying mechanisms and mechanistic irrelevance of the formal two-site model

The formal mechanism of linear mixed and non-competitive enzyme inhibition implies the binding of inhibitors to both the active site of the free enzyme in competition with the substrate, and to an allosteric site on the enzyme-substrate complex. However, it is evident from a review of the scientific literature that the two-site mechanism is frequently mistaken as the actual underlying mechanism of mixed inhibition. In this study, we conducted a comprehensive assessment of the mechanistic relevance of this type of inhibition using a statistical approach. By combining a statistical analysis of the inhibition cases documented in the BRENDA database with a theoretical investigation of inhibition models, we conclude that mixed inhibitors exclusively bind to the active site of enzymes. Hence ruling out any implication of allosteric sites and depriving the two-site model of any mechanistic relevance.

Differential Impact of Zinc Salt Precursors on Physiognomies, Anticancerous, and Antibacterial Activities of Zinc Oxide Nanoparticles

Zinc oxide nanoparticles (ZnONPs) are enormously popular semi-conductor metal oxides with diverse applications in every field of science. Many physical and chemical methods applied for the synthesis of ZnONPs are being rejected due to their environmental hazards. Therefore, ZnONPs synthesized from plant extracts are steered as eco-friendly showing more biocompatibility and biodegradability. Additionally, various synthesis conditions such as the type of precursor salt also play a role in influencing the physicochemical and biological properties of ZnONPs. In this study, green synthesis of ZnONPs from Acacia nilotica was carried out using zinc acetate (ZA-AN-ZNPs), zinc nitrate (ZN-AN-ZNPs), and zinc sulfate (ZS-AN-ZNPs) precursor salts. Surprisingly, characterization of ZnONPs using UV-visible spectroscopy, TEM, XRD, and EDX revealed the important role precursor salts played in influencing the size and shape of ZnONPs, i.e., 20-23 nm spherical (ZA-AN-ZNPs), 55-59 nm triangular (ZN-AN-ZNPs), and 94-97 nm nano-flowers (ZS-AN-ZNPs). FTIR analysis showed the involvement of alkaloids, alcohols, carboxylic acid, and phenolic compounds present in Acacia nilotica extract during the synthesis process. Since different precursor salts showed different morphology of ZnONPs, their biological activities were also variable. ZN-AN-ZNPs showed the highest cytotoxicity towards HepG2 cells with the lowest cell viability (28.92 ± 0.99%), highest ROS/RNS production (3425.3 ± 184.58 relative DHR123 fluorescence), and loss of mitochondrial membrane potential (1645.2 ± 32.12 relative fluorescence unit) as well as induced significant caspase-3 gene expression. In addition to this, studying the zone of inhibitions and minimum bactericidal and inhibitory concentrations of ZnONPs showed their exceptional potential as antibacterial agents. At MIC as low as 8 µg/mL, ZA-AN-ZNPs and ZN-AN-ZNPs exhibited significant bactericidal activities against human pathogens Klebsiella pneumoniae and Listeria monocytogenes, respectively. Furthermore, alkaline phosphatase, DNA/RNA leakage, and phosphate ion leakage studies revealed that a damage to the bacterial cell membrane and cell wall is involved in mediating the antibacterial effects of ZnONPs.

Nanomedicine for the Detection and Treatment of Ocular Bacterial Infections

Ocular bacterial infection is a prevalent cause of blindness worldwide, with substantial consequences for normal human life. Traditional treatments for ocular bacterial infections areless effective, necessitating the development of novel techniques to enable accurate diagnosis, precise drug delivery, and effective treatment alternatives. With the rapid advancement of nanoscience and biomedicine, increasing emphasis has been placed on multifunctional nanosystems to overcome the challenges posed by ocular bacterial infections. Given the advantages of nanotechnology in the biomedical industry, it can be utilized to diagnose ocular bacterial infections, administer medications, and treat them. In this review, the recent advancements in nanosystems for the detection and treatment of ocular bacterial infections are discussed; this includes the latest application scenarios of nanomaterials for ocular bacterial infections, in addition to the impact of their essential characteristics on bioavailability, tissue permeability, and inflammatory microenvironment. Through an in-depth investigation into the effect of sophisticated ocular barriers, antibacterial drug formulations, and ocular metabolism on drug delivery systems, this review highlights the challenges faced by ophthalmic medicine and encourages basic research and future clinical transformation based on ophthalmic antibacterial nanomedicine.

Recent advance on nanoparticles or nanomaterials with anti-multidrug resistant bacteria and anti-bacterial biofilm properties: A systematic review

Objective

With the wide spread of Multidrug-resistant bacteria (MDR) due to the transfer and acquisition of antibiotic resistance genes and the formation of microbial biofilm, various researchers around the world are looking for a solution to overcome these resistances. One potential strategy and the best candidate to overcome these infections is using an effective nanomaterial with antibacterial properties against them.

Methods

and analysis: In this study, we overview nanomaterials with anti-MDR bacteria and anti-biofilm properties. Hence, we systematically explored biomedical databases (Web of Sciences, Google Scholar, PubMed, and Scopus) to categorize related studies about nanomaterial with anti-MDR bacteria and anti-biofilm activities from 2007 to December 2022.

Results

In total, forty-one studies were investigated to find antibacterial and anti-biofilm information about the nanomaterial during 2007-2022. According to the collected documents, nineteen types of nanomaterial showed putative antibacterial effects such as Cu, Ag, Au, Au/Pt, TiO2, Al2O3, ZnO, Se, CuO, Cu/Ni, Cu/Zn, Fe3O4, Au/Fe3O4, Au/Ag, Au/Pt, Graphene O, and CuS. In addition, seven types of them considered as anti-biofilm agents such as Ag, ZnO, Au/Ag, Graphene O, Cu, Fe3O4, and Au/Ag.

Conclusion

According to the studies, each of nanomaterial has been designed with different methods and their effects against standard strains, clinical strains, MDR strains, and bacterial biofilms have been investigated in-vitro and in-vivo conditions. In addition, nanomaterials have different destructive mechanism on bacterial structures. Various nanoparticles (NP) introduced as the best candidate to designing new drug and medical equipment preventing infectious disease outbreaks by overcome antibiotic resistance and bacterial biofilm.

Applied Methods to Assess the Antimicrobial Activity of Metallic-Based Nanoparticles

With the rise of antibiotic resistance, the drive to discover novel antimicrobial substances and standard testing methods with the aim of controlling transmissive diseases are substantially high. In healthcare sectors and industries, although methods for testing antibiotics and other aqueous-based reagents are well established, methods for testing nanomaterials, non-polar and other particle-based suspensions are still debatable. Hence, utilities of ISO standard validations of such substances have been recalled where corrective actions had to be taken. This paper reports a serial analysis obtained from testing the antimicrobial activities of 10 metallic-based nanomaterials against 10 different pathogens using five different in vitro assays, where the technique, limitation and robustness of each method were evaluated. To confirm antimicrobial activities of metallic-based nanomaterial suspensions, it was found that at least two methods must be used, one being the agar well diffusion method, which was found to be the most reliable method. The agar well diffusion method provided not only information on antimicrobial efficacy through the size of the inhibitory zones, but it also identified antimicrobial ions and synergistic effects released by the test materials. To ascertain the effective inhibitory concentration of nanoparticles, the resazurin broth dilution method is recommended, as MIC can be determined visually without utilising any equipment. This method also overcomes the limit of detection (LoD) and absorbance interference issues, which are often found in the overexpression of cell debris and nanoparticles or quantum dots with optical profiles. In this study, bimetallic AgCu was found to be the most effective antimicrobial nanoparticle tested against across the bacterial (MIC 7 µg/mL) and fungal (MIC 62.5 µg/mL) species.

Zinc Oxide Nanoparticles Affect Early Seedlings' Growth and Polar Metabolite Profiles of Pea (Pisum sativum L.) and Wheat (Triticum aestivum L.)

The growing interest in the use of zinc oxide nanoparticles (ZnO NPs) in agriculture creates a risk of soil contamination with ZnO NPs, which can lead to phytotoxic effects on germinating seeds and seedlings. In the present study, the susceptibility of germinating seeds/seedlings of pea and wheat to ZnO NPs of various sizes (≤50 and ≤100 nm) applied at concentrations in the range of 100-1000 mg/L was compared. Changes in metabolic profiles in seedlings were analyzed by GC and GC-MS methods. The size-dependent harmful effect of ZnO NPs on the seedling's growth was revealed. The more toxic ZnO NPs (50 nm) at the lowest concentration (100 mg/L) caused a 2-fold decrease in the length of the wheat roots. In peas, the root elongation was slowed down by 20-30% only at 1000 mg/L ZnO NPs. The metabolic response to ZnO NPs, common for all tested cultivars of pea and wheat, was a significant increase in sucrose (in roots and shoots) and GABA (in roots). In pea seedlings, an increased content of metabolites involved in the aspartate-glutamate pathway and the TCA cycle (citrate, malate) was found, while in wheat, the content of total amino acids (in all tissues) and malate (in roots) decreased. Moreover, a decrease in products of starch hydrolysis (maltose and glucose) in wheat endosperm indicates the disturbances in starch mobilization.

Chiral Sulfur Nanosheets for Dual-Selective Inhibition of Gram-Positive Bacteria

Elemental sulfur is the oldest known antimicrobial agent. However, conventional sulfur in the clinic suffers from poor aqueous solubility and limited antibacterial activity, greatly hindering its practical use. Herein, we report a reform strategy coupling dimension engineering with chirality transfer to convert conventional 3D sulfur particles into chiral 2D sulfur nanosheets (S-NSs), which exhibit 50-fold improvement of antibacterial capability and dual-selective inhibition against Gram-positive bacteria. Benefiting from the inherent selectivity of S-NSs and chirality selectivity from decorated d-histidine, the obtained chiral S-NSs are proven to precisely kill Gram-positive drug-resistant bacteria, while no obvious bacterial inhibition is observed for Gram-negative bacteria. Mechanism studies reveal that S-NSs produce numerous reactive oxygen specipoes and hydrogen sulfide after incubation with bacteria, thus causing bacterial membrane destruction, respiratory chain damage, and ATP production inhibition. Upon spraying chiral S-NSs dispersions onto MRSA-infected wounds, the skin healing process was greatly accelerated in 8 days due to metabolism inhibition and oxidative damage of bacteria, indicating the excellent treatment efficiency of MRSA-infected wounds. This work converts the traditional well-known sulfur into modern antibacterial agents with a superior Gram-selectivity bactericidal capability.

Synergistic Antibacterial Effects of Amoxicillin and Gold Nanoparticles: A Therapeutic Option to Combat Antibiotic Resistance

Compacted Au@16-mph-16/DNA-AMOX (NSi) nanosystems were prepared from amoxicillin (AMOX) and precursor Au@16-mph-16 gold nanoparticles (Ni) using a Deoxyribonucleic acid (DNA) biopolymer as a glue. The synthesized nanocarrier was tested on different bacterial strains of Escherichia coli, Staphylococcus aureus, and Streptococcus pneumoniae to evaluate its effectiveness as an antibiotic as well as its internalization. Synthesis of the nanosystems required previous structural and thermodynamic studies using circular dichroism (CD) and UV-visible techniques to guarantee optimal complex formation and maximal DNA compaction, characteristics which facilitate the correct uptake of the nanocarrier. Two nanocomplexes with different compositions and structures, denoted NS1 and NS2, were prepared, the first involving external Au@16-mph-16 binding and the second partial intercalation. The Ni and NSi nanosystems obtained were characterized via transmission electron microscopy (TEM), zeta potential, and dynamic light scattering (DLS) techniques to measure their charge, aggregation state and hydrodynamic size, and to verify their presence inside the bacteria. From these studies, it was concluded that the zeta potential values for gold nanoparticles, NS1, and NS2 nanosystems were 67.8, -36.7, and -45.1 mV. Moreover, the particle size distribution of the Au@16-mph-16 gold nanoparticles and NS2 nanoformulation was found to be 2.6 nm and 69.0 nm, respectively. However, for NS1 nanoformulation, a bimodal size distribution of 44 nm (95.5%) and 205 nm (4.5%) was found. Minimal inhibitory concentration (MIC) values were determined for the bacteria studied using a microdilution plates assay. The effect on Escherichia coli bacteria was notable, with MIC values of 17 µM for both the NS1 and NS2 nanosystems. The Staphylococcus aureus chart shows a greater inhibition effect of NS2 and NP2 in non-diluted wells, and clearly reveals a great effect on Streptococcus pneumoniae, reaching MIC values of 0.53 µM in more diluted wells. These results are in good agreement with TEM internalization studies of bacteria that reveal significant internalization and damage in Streptococcus pneumoniae. In all the treatments carried out, the antibiotic capacity of gold nanosystems as enhancers of amoxicillin was demonstrated, causing both the precursors and the nanosystems to act very quickly, and thus favoring microbial death with a small amount of antibiotic. Therefore, these gold nanosystems may constitute an effective therapy to combat resistance to antibiotics, in addition to avoiding the secondary effects derived from the administration of high doses of antibiotics.

Emerging antibacterial nanozymes for wound healing

Wound infections continuously impose a huge economic and social burden on public healthcare. Despite the effective treatment of bacteria-infected wounds after using traditional antibiotics, the misuse of antibiotics usually causes the spread of bacterial resistance and decreases therapeutic outcomes. Therefore, the development of efficient antibacterial agents is urgently needed. Nanozymes, as a new generation of artificial enzymes, combine the intrinsic abilities of nanomaterials and natural enzymes. Recently, nanozymes has been widely developed to kill bacteria and treat wound infections by catalyzing the generation of various reactive oxygen species. Thus, this new concept of "antibacterial nanozymes" will promote the further advances of connecting nanozymes and bacterial elimination. To highlight these achievements, we summarize different types of antibacterial nanozymes for wound healing. It is believed that such a promising therapeutic strategy of developing antibacterial nanozymes will make a great contribution in the field of skin regeneration. We expect that antibacterial nanozymes will play the significant roles in both basic research and clinical applications.

Phytofabrication of Selenium Nanoparticles with Moringa oleifera (MO-SeNPs) and Exploring Its Antioxidant and Antidiabetic Potential

The advancement in nanotechnology is the trigger for exploring the synthesis of selenium nanoparticles and their use in biomedicine. Therefore, this study aims to synthesize selenium nanoparticles using M. oleifera as a reducing agent and evaluate their antioxidant and antidiabetic potential. Our result demonstrated a change in the color of the mixture from yellow to red, and UV-Vis spectrometry of the suspension solution confirmed the formation of MO-SeNPs with a single absorbance peak in the range of 240-560 nm wavelength. FTIR analysis revealed several bioactive compounds, such as phenols and amines, that could possibly be responsible for the reduction and stabilization of the MO-SeNPs. FESEM + EDX analysis revealed that the amorphous MO-SeNPs are of high purity, have a spherical shape, and have a size of 20-250 nm in diameter, as determined by HRTEM. MO-SeNPs also exhibit the highest DPPH scavenging activity of 84% at 1000 μg/mL with an IC50 of 454.1 μg/mL and noteworthy reducing ability by reducing power assay. Furthermore, MO-SeNPs showed promising antidiabetic properties with dose-dependent inhibition of α-amylase (26.7% to 44.53%) and α-glucosidase enzyme (4.73% to 19.26%). Hence, these results demonstrated that M. oleifera plant extract possesses the potential to reduce selenium ions to SeNPs under optimized conditions with notable antioxidant and antidiabetic activities.

Transition metal-based nanoparticles as potential antimicrobial agents: recent advancements, mechanistic, challenges, and future prospects

Bacterial transmission is considered one of the potential risks for communicable diseases, requiring promising antibiotics. Traditional drugs possess a limited spectrum of effectiveness, and their frequent administration reduces effectiveness and develops resistivity. In such a situation, we are left with the option of developing novel antibiotics with higher efficiency. In this regard, nanoparticles (NPs) may play a pivotal role in managing such medical situations due to their distinct physiochemical characteristics and impressive biocompatibility. Metallic NPs are found to possess extraordinary antibacterial effects that are useful in vitro as well as in vivo as self-modified therapeutic agents. Due to their wide range of antibacterial efficacy, they have potential therapeutic applications via diverse antibacterial routes. NPs not only restrict the development of bacterial resistance, but they also broaden the scope of antibacterial action without binding the bacterial cell directly to a particular receptor with promising effectiveness against both Gram-positive and Gram-negative microbes. This review aimed at exploring the most relevant types of metal NPs employed as antimicrobial agents, particularly those based on Mn, Fe, Co, Cu, and Zn metals, and their antimicrobial mechanisms. Further, the challenges and future prospects of NPs in biological applications are also discussed.

Effects of NO3-, Cl-, and CH3COO- anions and diethylene glycol on the morphological, structural, antidiabetic, and cell viability properties of CeO2 nanoparticles

Cerium oxide (CeO₂) nanoparticles (NPs) were synthesized using a modified conventional polyol method. The ratio of diethylene glycol (DEG) and water in the synthesis was varied, and three different cerium precursor salts (Ce(NO₃)₃, CeCl₃, and Ce(CH₃COO)₃) were used. The structure, size, and morphology of the synthesized CeO₂ NPs were studied. An average crystallite size of 13 to 33 nm was obtained from the XRD analysis. Spherical and elongated morphologies of the synthesized CeO₂ NPs were acquired. Average particle sizes in the range of 16-36 nm were obtained by varying different ratios of DEG and water. The presence of DEG molecules on the surface of CeO₂ NPs was confirmed using FTIR. Synthesized CeO₂ NPs were used to study the antidiabetic and cell viability (cell cytotoxicity) properties. Antidiabetic studies were carried out using α-glucosidase enzymes inhibition activity. CeO₂ synthesized using Ce(NO₃)₃ and CeCl₃ precursors showed approximately 40.0% α-glucosidase enzyme inhibition activity, while CeO₂ synthesized using Ce(CH₃COO)₃ showed the lowest α-glucosidase enzyme inhibition activity. Cell viability properties of CeO₂ NPs were investigated using an in vitro cytotoxicity test. CeO₂ NPs prepared using Ce(NO₃)₃ and CeCl₃ were non-toxic at lower concentrations, while CeO₂ NPs prepared using Ce(CH₃COO)₃ were non-toxic at all concentrations. Therefore, polyol-mediated synthesized CeO₂ NPs showed quite good α-glucosidase inhibition activity and biocompatibility.

Flexible free-standing antibacterial nanoporous Ag ribbon

The biomedical field has the potential to significantly benefit from the use of flexible free-standing Ag nanostructures due to their outstanding mechanical and antibacterial properties. However, the intricate process of synthesizing these nanostructures, as well as the potential toxicity of nanostructured Ag, pose significant challenges. This study used a facile etching method to synthesize the free-standing nanoporous Ag (NP-Ag) ribbons with a homogeneous and bicontinuous three-dimensional ligament structure. The free-standing NP-Ag ribbons demonstrated stable mechanical performance and excellent flexibility when subjected to various deformation states on artificial fingers. Additionally, the NP-Ag ribbons exhibited remarkable antibacterial capacity with rates of 99.81 ± 0.14% against Escherichia coli, 96.11 ± 1.49% against Staphylococcus aureus, and 95.37 ± 1.24% against methicillin-resistant Staphylococcus aureus. The antibacterial mechanism of NP-Ag is attributed to the rapid release of Ag ions (Ag⁺) in 24 h, causing damage to the bacterial membrane. Moreover, the in vivo results demonstrate that the NP-Ag ribbons provide rapid antibacterial efficacy and are biosafe due to the long-term stable Ag⁺ release of NP-Ag. The development of these free-standing flexible NP-Ag ribbons offers a new avenue for wearable antibacterial applications.

Domain-agnostic predictions of nanoscale interactions in proteins and nanoparticles

Although challenging, the accurate and rapid prediction of nanoscale interactions has broad applications for numerous biological processes and material properties. While several models have been developed to predict the interaction of specific biological components, they use system-specific information that hinders their application to more general materials. Here we present NeCLAS, a general and efficient machine learning pipeline that predicts the location of nanoscale interactions, providing human-intelligible predictions. NeCLAS outperforms current nanoscale prediction models for generic nanoparticles up to 10-20 nm, reproducing interactions for biological and non-biological systems. Two aspects contribute to these results: a low-dimensional representation of nanoparticles and molecules (to reduce the effect of data uncertainty), and environmental features (to encode the physicochemical neighborhood at multiple scales). This framework has several applications, from basic research to rapid prototyping and design in nanobiotechnology.

Three-dimension chitosan hydrogel loading melanin composite nanoparticles for wound healing by anti-bacteria, immune activation and macrophage autophagy promotion

Application of Combined photodynamic therapy (PDT) and photothermal therapy (PTT) has become one of the most promising strategy to replace antibiotics and avoid the epidemic of drug-resistant strains during wound healing. However, high amount of reactive oxygen species (ROS) and high temperature cause severe stress response to normal tissues, leading to potential risks of wound healing. Herein, a three-dimension chitosan hydrogel melanin-glycine-C60 nanoparticles (MGC NPs) were prepared to realized effective anti-bacterial activity, immune activation and macrophage autophagy promotion in three-dimensional wound space without triggering stress response. MGC NP is a composite polymer material composed of natural melanin polymer, oligopeptide and carbon-based material, which showed excellent biological safety. By regulating the peptide length between melanin and C60 and nanoparticle content, a high ROS/heat environment at the upper wound site and a low ROS/heat environment at the lower region adjacent to the wound tissue were established to obtain a three-dimension hydrogel with precise PDT and PTT efficiency in different regions. Highly effective PDT/PTT was used to kill microorganisms in upper region, thus providing a barrier to reduce microbial infection. Mild PDT/PTT in lower region promoted the polarization of M1 macrophage to M2 macrophage and activated autophagy of M2 macrophages, regulating the immune microenvironment and promoting wound repair. In conclusion, the novel three-dimensional PDT/PTT therapy based on natural macromolecules proposed in this study accelerates wound healing through dual pathways on the premise of avoiding wound stress response, which is of great significance for the development of clinical strategies for phototherapy.

Glucose Oxidase-Integrated Metal-Polyphenolic Network as a Microenvironment-Activated Cascade Nanozyme for Hyperglycemic Wound Disinfection

The high systemic blood glucose concentration of hyperglycemic wound microenvironment (WME) severely impedes the disinfection and healing of infected skin wounds. Herein, a WME-activated smart natural product, integrated GOx-GA-Fe nanozyme (GGFzyme), is engineered, which combines a nanozyme and natural enzyme to promote reactive oxygen species (ROS) generation in situ for hyperglycemic wound disinfection. GGFzyme can consume a high concentration of glucose in hyperglycemia wounds and generate H₂O₂. The conversion of glucose into gluconic acid not avails starvation treatment but reduces the pH of WME to elevate the catalytic activities of both the nanozyme (GA-Fe) and natural enzyme (GOx). And H₂O₂ is then high efficiently catalyzed into ^•OH and O₂^•- in situ to combat pathogenic bacteria and promote wound disinfection. The high catalytic antibacterial capacity and superior biosafety, combined with beneficial WME modulation, demonstrate that GGFzyme is a promising therapeutic agent for hyperglycemic wounds.

Struct2Graph: a graph attention network for structure based predictions of protein–protein interactions

Background

Development of new methods for analysis of protein–protein interactions (PPIs) at molecular and nanometer scales gives insights into intracellular signaling pathways and will improve understanding of protein functions, as well as other nanoscale structures of biological and abiological origins. Recent advances in computational tools, particularly the ones involving modern deep learning algorithms, have been shown to complement experimental approaches for describing and rationalizing PPIs. However, most of the existing works on PPI predictions use protein-sequence information, and thus have difficulties in accounting for the three-dimensional organization of the protein chains.

Results

In this study, we address this problem and describe a PPI analysis based on a graph attention network, named Struct2Graph, for identifying PPIs directly from the structural data of folded protein globules. Our method is capable of predicting the PPI with an accuracy of 98.89% on the balanced set consisting of an equal number of positive and negative pairs. On the unbalanced set with the ratio of 1:10 between positive and negative pairs, Struct2Graph achieves a fivefold cross validation average accuracy of 99.42%. Moreover, Struct2Graph can potentially identify residues that likely contribute to the formation of the protein–protein complex. The identification of important residues is tested for two different interaction types: (a) Proteins with multiple ligands competing for the same binding area, (b) Dynamic protein–protein adhesion interaction. Struct2Graph identifies interacting residues with 30% sensitivity, 89% specificity, and 87% accuracy.

Conclusions

In this manuscript, we address the problem of prediction of PPIs using a first of its kind, 3D-structure-based graph attention network (code available at https://github.com/baranwa2/Struct2Graph). Furthermore, the novel mutual attention mechanism provides insights into likely interaction sites through its unsupervised knowledge selection process. This study demonstrates that a relatively low-dimensional feature embedding learned from graph structures of individual proteins outperforms other modern machine learning classifiers based on global protein features. In addition, through the analysis of single amino acid variations, the attention mechanism shows preference for disease-causing residue variations over benign polymorphisms, demonstrating that it is not limited to interface residues.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12859-022-04910-9.

Detection and Quantification of Nanoparticle-Induced Intracellular ROS in Live Cells by Laser Scanning Confocal Microscopy

All living organisms utilise reactive oxygen species (ROS) for essential cellular functions, the majority of which involve signal transduction pathways, such as enzyme regulation, cell growth and differentiation signalling, and inflammation mediation. Increased ROS in cancer cells can be caused by abnormalities in the tumor environment. However, using fluorescence microscopy to detect and quantify ROS changes in biological systems is difficult for several reasons: (1) lack of specificity of ROS-sensitive probes, (2) high turnover of ROS species, (3) rapid decrease in ROS fluorescence with time, and (4) detection and quantification techniques with insufficient sensitivity. Existing approaches to ROS measurement using confocal microscopy imaging focus solely on ROS detection rather than quantification. A novel fluorescence-based ROS detection and quantification technique has been developed for the purpose of resolving the limitations of existing methods. In general, ROS is detected by fluorescence using instrumentation such as flow cytometry and laser scanning confocal microscopy. However, these approaches confirm only the presence or absence of ROS; they are not quantitative, which is essential for therapeutic applications. In the newly developed technique, cerium-based ROS-generating nanoparticles have been used to elevate the ROS in HT-1080 fibrosarcoma cells. The elevated ROS levels are detected using an H2DCFDA fluorescence probe, which is used widely for this application, and captured as digital images using a 488 nm fluorescence channel. Quantification of the ROS is achieved using script in MATLAB software to convert the fluorescence intensities to numerical values. Thus, this technique nearly simultaneously integrates both detection and quantification of the ROS, which provides the statistical justification necessary to support therapeutic translation.

Copper-containing nanoparticles: Mechanism of antimicrobial effect and application in dentistry-a narrative review

Copper has been used as an antimicrobial agent long time ago. Nowadays, copper-containing nanoparticles (NPs) with antimicrobial properties have been widely used in all aspects of our daily life. Copper-containing NPs may also be incorporated or coated on the surface of dental materials to inhibit oral pathogenic microorganisms. This review aims to detail copper-containing NPs' antimicrobial mechanism, cytotoxic effect and their application in dentistry.

Advanced Strategies in Enzyme Activity Regulation for Biomedical Applications

Enzymes are important macromolecular biocatalysts that accelerate chemical and biochemical reactions in living organisms. Most human diseases are related to alterations in enzyme activity. Moreover, enzymes are potential therapeutic tools for treating different diseases, such as cancer, infections, and cardiovascular and cerebrovascular diseases. Precise remote enzyme activity regulation provides new opportunities to combat diseases. This review summarizes recent advances in the field of enzyme activity regulation, including reversible and irreversible regulation. It also discusses the mechanisms and approaches for on-demand control of these activities. Furthermore, a range of stimulus-responsive inhibitors, polymers, and nanoparticles for regulating enzyme activity and their prospective biomedical applications are summarized. Finally, the current challenges and future perspectives on enzyme activity regulation are discussed.

Enzyme Nanoscale Interactions with Manganese Zinc Sulfide Give Insight into Potential Antiviral Mechanisms and SARS-CoV-2 Inhibition

Recent interest in nanomedicine has skyrocketed because of mRNA vaccine lipid nanoparticles (LNPs) against COVID-19. Ironically, despite this success, the innovative nexus between nanotechnology and biochemistry, and the impact of nanoparticles on enzyme biochemical activity is poorly understood. The studies of this group on zinc nanoparticle (ZNP) compositions suggest that nanorod morphologies are preferred and that ZNP doped with manganese or iron can increase activity against model enzymes such as luciferase, DNA polymerase, and β-galactosidase (β-Gal), with the latter previously being associated with antimicrobial activity. SARS-CoV-2 encodes several of these types of oxido-reductase, polymerase, or hydrolase types of enzymes, and while metamaterials or nanoparticle composites have become important in many fields, their application against SARS-CoV-2 has only recently been considered. Recently, this group discovered the antiviral activity of manganese-doped zinc sulfide (MnZnS), and here the interactions of this nanoparticle composite with β-Gal, angiotensin converting enzyme (ACE), and human ACE2 (hACE2), the SARS-CoV-2 receptor, are demonstrated. Low UV, circular dichroism, and zeta potential results confirm their enzyme interaction and inhibition by fluorometric area under the curve (AUC) measurements. The IC₅₀ of enzyme activity varied depending on the manganese percentage and surface ranging from 20 to 50 μg/mL. MnZnS NPs give a 1–2 log order inhibition of SARS-CoV-2; however, surface-capping with cysteine does not improve activity. These data suggest that Mn substituted ZNP interactions to hACE2 and potentially other enzymes may underlie its antiviral activity, opening up a new area of pharmacology ready for preclinical translation.

Zinc associated nanomaterials and their intervention in emerging respiratory viruses: Journey to the field of biomedicine and biomaterials

Respiratory viruses represent a severe public health risk worldwide, and the research contribution to tackle the current pandemic caused by the SARS-CoV-2 is one of the main targets among the scientific community. In this regard, experts from different fields have gathered to confront this catastrophic pandemic. This review illustrates how nanotechnology intervention could be valuable in solving this difficult situation, and the state of the art of Zn-based nanostructures are discussed in detail. For virus detection, learning from the experience of other respiratory viruses such as influenza, the potential use of Zn nanomaterials as suitable sensing platforms to recognize the S1 spike protein in SARS-CoV-2 are shown. Furthermore, a discussion about the antiviral mechanisms reported for ZnO nanostructures is included, which can help develop surface disinfectants and protective coatings. At the same time, the properties of Zn-based materials as supplements for reducing viral activity and the recovery of infected patients are illustrated. Within the scope of noble adjuvants to improve the immune response, the ZnO NPs properties as immunomodulators are explained, and potential prototypes of nanoengineered particles with metallic cations (like Zn2+) are suggested. Therefore, using Zn-associated nanomaterials from detection to disinfection, supplementation, and immunomodulation opens a wide area of opportunities to combat these emerging respiratory viruses. Finally, the attractive properties of these nanomaterials can be extrapolated to new clinical challenges.

Silica Nanoparticle Acute Toxicity on Male Rattus norvegicus Domestica: Ethological Behavior, Hematological Disorders, Biochemical Analyses, Hepato-Renal Function, and Antioxidant-Immune Response

With extensive production and various applications of silica nanoparticles (SiNPs), there is a controversy regarding the ecotoxicological impacts of SiNPs. Therefore, the current study was aimed to assess the acute toxicity of silica nanoparticles in male Rattus norvegicus domestica after 24 and 96 h. Hematological, serum biochemical, stress biomarker, and immune-antioxidant parameters were addressed. Chemical composition, crystal structure, and the particle shape and morphology of SiNPs were investigated using XRD, FTIR, BET, UV-Vis, and SEM, while TEM was used to estimate the average size distribution of particles. For the exposure experiment, 48 male rats were divided into four groups (12 rat/group) and gavaged daily with different levels of zero (control), 5, 10, and 20 mg of SiNPs corresponding to zero, 31.25, 62.5, and 125 mg per kg of body weight. Sampling was carried out after 24 and 96 h. Relative to the control group, the exposure to SiNPs induced clear behavioral changes such as inactivity, lethargy, aggressiveness, and screaming. In a dose-dependent manner, the behavior scores recorded the highest values. Pairwise comparisons with the control demonstrated a significant (p < 0.05) decrease in hematological and immunological biomarkers [lysozymes and alternative complement activity (ACH50)] with a concomitant reduction in the antioxidant enzymes [catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD)] in all exposed groups to SiNPs. On the contrary, there was a noticeable increase in biochemical parameters (glucose, cortisol, creatinine, urea, low-density lipoproteins (LDL), high-density lipoproteins (HDL), total protein, and albumin) and hepato-renal indicators, including alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), of all SiNP-exposed groups. It was observed that SiNPs induced acute toxicity, either after 24 h or 96 h, post-exposure of rats to SiNPs evidenced by ethological changes, hepato-renal dysfunction, hyperlipemia, and severe suppression in hematological, protein, stress, and immune-antioxidant biomarkers reflecting an impaired physiological status. The obtained outcomes create a foundation for future research to consider the acute toxicity of nanoparticles to preserve human health and sustain the environment.

Unifying structural descriptors for biological and bioinspired nanoscale complexes

Biomimetic nanoparticles are known to serve as nanoscale adjuvants, enzyme mimics and amyloid fibrillation inhibitors. Their further development requires better understanding of their interactions with proteins. The abundant knowledge about protein-protein interactions can serve as a guide for designing protein-nanoparticle assemblies, but the chemical and biological inputs used in computational packages for protein-protein interactions are not applicable to inorganic nanoparticles. Analysing chemical, geometrical and graph-theoretical descriptors for protein complexes, we found that geometrical and graph-theoretical descriptors are uniformly applicable to biological and inorganic nanostructures and can predict interaction sites in protein pairs with accuracy >80% and classification probability ~90%. We extended the machine-learning algorithms trained on protein-protein interactions to inorganic nanoparticles and found a nearly exact match between experimental and predicted interaction sites with proteins. These findings can be extended to other organic and inorganic nanoparticles to predict their assemblies with biomolecules and other chemical structures forming lock-and-key complexes.

Se nanoparticles stabilized with Allamanda cathartica L. flower extract inhibited phytopathogens and promoted mustard growth under salt stress

Selenium Nanoparticles (SeNPs) exhibit tremendous application in agriculture as antimicrobials or as nano fertilizer. Present work reports the eco-friendly synthesis of SeNPs by using Allamanda cathartica L. flower extract (aqueous) as a reducing/capping agent and selenium dioxide as a precursor. The method used here is free of any toxic reducing agents and organic solvents. The synthesis process of SeNPs took 5 h at 60 °C, confirmed by the brick red colour of the solution followed by UV-Vis spectroscopy and further characterized by XRD, FTIR, EDX and SEM. The average size (diameter) of the SeNPs were found to be 60.31 nm by DLS. It has shown strong antimicrobial activity against Pseudomonas marginalis and P. aeruginosa at 2.5, 5 and 10 mg/mL concentrations. Besides, its application improved seed germination and growth parameters of Brassica campestris (TS 36 variety) under salt stress. 25 mg/L SeNPs has improved the germination percentage by around 31%, shoot length by 92%, root length by 78% and total chlorophyll content by 49% under 200 mM NaCl stress. This SeNPs could be a potential antimicrobial agent in treating plant diseases caused by the mentioned phytopathogens, having no or minimum toxicity, in fact having positive impacts on plant growth.

Photo-regulated dual-functional zinc oxide nanocomposite for synergistic sterilization and antioxidant treatment

The C-FZnO-RT composite achieved synergistic bactericidal performance against both E. coli and S. aureus under light conditions.

Modulation of Acetylcholinesterase Activity Using Molecularly Imprinted Polymer Nanoparticles

Modulation of enzyme activity allows for control over many biological pathways and while strategies for the pharmaceutical design of inhibitors are well established; methods for promoting activation, that is an...

An intrinsically thermogenic nanozyme for synergistic antibacterial therapy

Bacterial infections with a high mortality rate have become serious health issues for human beings. As natural enzymes play an important role in the survival and proliferation of bacteria, effective inhibition of bacterial natural enzyme activities is important for antimicrobial therapy. Herein, a novel enzymatic antibacterial strategy, of enhancing nanozyme activity but reducing bacterial natural enzyme activity, is developed based on yolk-shell Fe₂C@Fe₃O₄-PEG thermogenic nanozymes with highly magnetothermal properties and thermal-enhanced peroxidase-like activities. When applying an alternating magnetic field, the special yolk-shell Fe₂C@Fe₃O₄-PEG nanozymes show a better magnetothermal effect than Fe₂C (yolk) and Fe₃O₄ (shell) due to the increased value of their magnetic energy product, and the peroxidase-like activity of the nanozymes is further improved. Meanwhile, remarkably restrained by the enhanced magnetothermal effect from the nanozymes, typical natural enzyme activities of bacteria are detected with an inhibition rate of nearly 80%. Both in vitro and in vivo experiments exhibit superior synergistic antibacterial efficacy. The antimicrobial mechanisms are explained as the reduction of natural enzyme activities and the disruption of cell walls and membranes induced by the self-magnetothermal effect of nanozymes along with the production of abundant ˙OH radicals derived from the thermal-enhanced peroxidase-like activity of nanozymes. Overall, this work focuses on an intrinsically thermogenic nanozyme, which provides a potential platform for future synergistic antibacterial application.

Past and Current Progress in the Development of Antiviral/Antimicrobial Polymer Coating towards COVID-19 Prevention: A Review

The astonishing outbreak of SARS-CoV-2 coronavirus, known as COVID-19, has attracted numerous research interests, particularly regarding fabricating antimicrobial surface coatings. This initiative is aimed at overcoming and minimizing viral and bacterial transmission to the human. When contaminated droplets from an infected individual land onto common surfaces, SARS-CoV-2 coronavirus is able to survive on various surfaces for up to 9 days. Thus, the possibility of virus transmission increases after touching or being in contact with contaminated surfaces. Herein, we aim to provide overviews of various types of antiviral and antimicrobial coating agents, such as antimicrobial polymer-based coating, metal-based coating, functional nanomaterial, and nanocomposite-based coating. The action mode for each type of antimicrobial agent against pathogens is elaborated. In addition, surface properties of the designed antiviral and antimicrobial polymer coating with their influencing factors are discussed in this review. This paper also exhibits several techniques on surface modification to improve surface properties. Various developed research on the development of antiviral/antimicrobial polymer coating to curb the COVID-19 pandemic are also presented in this review.

Plant-derived nanotherapeutic systems to counter the overgrowing threat of resistant microbes and biofilms

Since antiquity, the survival of human civilization has always been threatened by the microbial infections. An alarming surge in the resistant microbial strains against the conventional drugs is quite evident in the preceding years. Furthermore, failure of currently available regimens of antibiotics has been highlighted by the emerging threat of biofilms in the community and hospital settings. Biofilms are complex dynamic composites rich in extracellular polysaccharides and DNA, supporting plethora of symbiotic microbial life forms, that can grow on both living and non-living surfaces. These enforced structures are impervious to the drugs and lead to spread of recurrent and non-treatable infections. There is a strong realization among the scientists and healthcare providers to work out alternative strategies to combat the issue of drug resistance and biofilms. Plants are a traditional but rich source of effective antimicrobials with wider spectrum due to presence of multiple constituents in perfect synergy. Other than the biocompatibility and the safety profile, these phytochemicals have been repeatedly proven to overcome the non-responsiveness of resistant microbes and films via multiple pathways such as blocking the efflux pumps, better penetration across the cell membranes or biofilms, and anti-adhesive properties. However, the unfavorable physicochemical attributes and stability issues of these phytochemicals have hampered their commercialization. These issues of the phytochemicals can be solved by designing suitably constructed nanoscaled structures. Nanosized systems can not only improve the physicochemical features of the encapsulated payloads but can also enhance their pharmacokinetic and therapeutic profile. This review encompasses why and how various types of phytochemicals and their nanosized preparations counter the microbial resistance and the biofouling. We believe that phytochemical in tandem with nanotechnological innovations can be employed to defeat the microbial resistance and biofilms. This review will help in better understanding of the challenges associated with developing such platforms and their future prospects.

Regulation of the Enzymatic Activities of Lysozyme by the Surface Ligands of Ultrasmall Gold Nanoclusters: The Role of Hydrophobic Interactions

Nanomaterials for biological applications would inevitably encounter and interact with biomolecules, which have a profound impact on the properties, functions, and even fates of both nanomaterials and biomolecules. Among the biomolecules, lysozyme (Lys) is of great importance in defending the bacterial intruder and maintaining health. Here, the interactions between fluorescent gold nanoclusters (AuNCs) (∼2 nm) capped with different surface ligands and Lys were thoroughly investigated. Fluorescence spectroscopic studies showed that dihydrolipoic acid (DHLA)-capped and glutathione (GSH)-capped AuNCs both quenched the intrinsic fluorescence of Lys by different quenching mechanisms. Agarose gel electrophoresis and zeta-potential assays showed that statistically one DHLA-AuNC could bind one Lys, while one GSH-AuNC could bind 3-4 Lys, providing new examples for the concept of a "protein complex". Activity assays indicated that DHLA-AuNCs heavily inhibited the enzymatic activity of Lys, while GSH-AuNCs had little effect. By synchronous fluorescence and circular dichroism spectroscopic studies, it was deduced that both AuNCs would interact with Lys by electrostatic attractions due to the distinct surface charges, and then DHLA-AuNCs would further interact with Lys by hydrophobic interactions, probably due to the hydrophobic carbon chain of DHLA and the hydrophobic side chains of amino acid residues in Lys, which was proved by the significant secondary structure changes caused by DHLA-AuNCs. Meanwhile, conformational changes induced by GSH-AuNCs with zwitterionic ligands were neglectable. Therefore, this work provided a comprehensive study of the consequences and mechanisms of the interactions between Lys and AuNCs, which was essential for the design and better use of nanomaterials as biological agents.

Hedgehog artificial macrophage with atomic-catalytic centers to combat Drug-resistant bacteria

Pathogenic drug-resistant bacteria represent a threat to human health, for instance, the methicillin-resistant Staphylococcus aureus (MRSA). There is an ever-growing need to develop non-antibiotic strategies to fight bacteria without triggering drug resistance. Here, we design a hedgehog artificial macrophage with atomic-catalytic centers to combat MRSA by mimicking the “capture and killing” process of macrophages. The experimental studies and theoretical calculations reveal that the synthesized materials can efficiently capture and kill MRSA by the hedgehog topography and substantial generation of •O₂⁻ and HClO with its Fe₂N₆O catalytic centers. The synthesized artificial macrophage exhibits a low minimal inhibition concentration (8 μg/mL Fe-Art M with H₂O₂ (100 μM)) to combat MRSA and rapidly promote the healing of bacteria-infected wounds on rabbit skin. We suggest that the application of this hedgehog artificial macrophage with “capture and killing” capability and high ROS-catalytic activity will open up a promising pathway to develop antibacterial materials for bionic and non-antibiotic disinfection strategies.

The increase in drug-resistant bacteria is a world-wide health issue that demands the development of alternatives to standard antibiotic treatments. In this study, the authors synthesise a hedgehog artificial macrophage with heme-mimetic catalytic centres, and peroxidase- and haloperoxidase-mimicking activities, for the treatment of methicillin-resistant Staphylococcus aureus.

Current approaches for the exploration of antimicrobial activities of nanoparticles

Infectious diseases of bacterial and viral origins contribute to substantial mortality worldwide. Collaborative efforts have been underway between academia and the industry to develop technologies for a more effective treatment for such diseases. Due to their utility in various industrial applications, nanoparticles (NPs) offer promising potential as antimicrobial agents against bacterial and viral infections. NPs have been established to possess potent antimicrobial activities against various types of pathogens due to their unique characteristics and cell-damaging ability through several mechanisms. The recently accepted antimicrobial mechanisms possessed by NPs include metal ion release, oxidative stress induction, and non-oxidative mechanisms. Another merit of NPs lies in the low likelihood of the development of microbial tolerance towards NPs, given the multiple simultaneous mechanisms of action against the pathogens targeting numerous gene mutations in these pathogens. Moreover, NPs provide a fascinating opportunity to curb microbial growth before infections: this outstanding feature has led to their utilization as active antimicrobial agents in different industrial applications, e.g. the coating of medical devices, incorporation in food packaging, promoting wound healing and encapsulation with other potential materials for wastewater treatment. This review discusses the progress and achievements in the antimicrobial applications of NPs, factors contributing to their actions, mechanisms underlying their efficiency, and risks of their applications, including the antimicrobial action of metal nanoclusters (NCs). The review concludes with a discussion of the restrictions on present studies and future prospects of nanotechnology-based NPs development.