Influence of Silver-hydroxyapatite Nanocomposite Coating on Biofilm Formation of Joint Prosthesis and Its Mechanism

Targeting bacterial biofilm-related genes with nanoparticle-based strategies

Persistent infection caused by biofilm is an urgent in medicine that should be tackled by new alternative strategies. Low efficiency of classical treatments and antibiotic resistance are the main concerns of the persistent infection due to biofilm formation which increases the risk of morbidity and mortality. The gene expression patterns in biofilm cells differed from those in planktonic cells. One of the promising approaches against biofilms is nanoparticle (NP)-based therapy in which NPs with multiple mechanisms hinder the resistance of bacterial cells in planktonic or biofilm forms. For instance, NPs such as silver (Ag), zinc oxide (ZnO), titanium dioxide (TiO2), copper oxide (Cu), and iron oxide (Fe3O4) through the different strategies interfere with gene expression of bacteria associated with biofilm. The NPs can penetrate into the biofilm structure and affect the expression of efflux pump, quorum-sensing, and adhesion-related genes, which lead to inhibit the biofilm formation or development. Therefore, understanding and targeting of the genes and molecular basis of bacterial biofilm by NPs point to therapeutic targets that make possible control of biofilm infections. In parallel, the possible impact of NPs on the environment and their cytotoxicity should be avoided through controlled exposure and safety assessments. This study focuses on the biofilm-related genes that are potential targets for the inhibition of bacterial biofilms with highly effective NPs, especially metal or metal oxide NPs.

In vitro Evaluation of Antibacterial Activity of Synthetic Zeolite Supported AgZno Nanoparticle Against a Selected Group of Bacteria

Background

The development of novel and intriguing nanoparticle (NP)-based materials with antibacterial activity has recently received attention due to the problem of bacterial resistance to conventional antibiotics becoming more and more frequent. Thus, this study aimed to investigate the antibacterial effectiveness of a synthetic zeolite-supported AgZnO nanoparticle against selected bacteria in vitro.

Methods

Using the disc diffusion method, the antibacterial activity of synthetic zeolite-supported AgZnO nanoparticles was assessed against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Zinc oxide (ZnO) and Ag/ZnO nanoparticles were used to create the zeolite-supported Ag/ZnO composite. Chloramphenicol was used as a standard drug. The nanoparticles and composites were characterized using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and atomic absorption spectroscopy (AAS).

Results

Synthetic zeolite-supported AgZnO nanoparticles showed promising antibacterial properties with the largest zone of inhibition against S. aureus bacteria in comparison to E. coli. The synthetic zeolite-supported AgZnO nanoparticle displayed a zone of inhibition against S. aureus and E. coli without a remarkable difference compared to the respective standard drug (Chloramphenicol). Zinc peaks were visible in the X-ray diffractograms, which supported the theory that the characteristic hexagonal wurtzite structure of zinc oxide was present.

Conclusion

All types of ZnO, AgZnO, and AgZnO-Zeolite showed wide-spectrum activity with better effect against gram-positive bacteria, while the Zeolite-Ag/ZnO composite showed even better antibacterial activity. The findings suggest a potential bactericide that needs further evaluation in future studies was observed in synthetic zeolite-supported Ag/ZnO nanoparticles.

Antimicrobial Activity Enhancers: Towards Smart Delivery of Antimicrobial Agents

The development of effective treatments against infectious diseases is an extensive and ongoing process due to the rapid adaptation of bacteria to antibiotic-based therapies. However, appropriately designed activity enhancers, including antibiotic delivery systems, can increase the effectiveness of current antibiotics, overcoming antimicrobial resistance and decreasing the chance of contributing to further bacterial resistance. The activity/delivery enhancers improve drug absorption, allow targeted antibiotic delivery, improve their tissue and biofilm penetration and reduce side effects. This review provides insights into various antibiotic activity enhancers, including polymer, lipid, and silver-based systems, designed to reduce the adverse effects of antibiotics and improve formulation stability and efficacy against multidrug-resistant bacteria.

Antibacterial Activity Evaluation of ZnO, CuO, and TiO2 Nanoparticles in Solution and Thin Films

This chapter introduces unique methodology of antibacterial activity evaluation of nanoparticles in both solution and thin films. Nanoparticles of ZnO, TiO₂, and CuO are synthesized via the sol-gel method. Antibacterial tests are carried out against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria using disk diffusion and bioluminescence. To perform antibacterial tests on thin films and to overcome bacterial strains recuperation on the supports, a new method of bacterial detaching from the slides is developed based on French standard NF EN 14561.

Nanomaterials in Wound Healing and Infection Control

Wounds continue to be a serious medical concern due to their increasing incidence from injuries, surgery, burns and chronic diseases such as diabetes. Delays in the healing process are influenced by infectious microbes, especially when they are in the biofilm form, which leads to a persistent infection. Biofilms are well known for their increased antibiotic resistance. Therefore, the development of novel wound dressing drug formulations and materials with combined antibacterial, antibiofilm and wound healing properties are required. Nanomaterials (NM) have unique properties due to their size and very large surface area that leads to a wide range of applications. Several NMs have antimicrobial activity combined with wound regeneration features thus give them promising applicability to a variety of wound types. The idea of NM-based antibiotics has been around for a decade at least and there are many recent reviews of the use of nanomaterials as antimicrobials. However, far less attention has been given to exploring if these NMs actually improve wound healing outcomes. In this review, we present an overview of different types of nanomaterials explored specifically for wound healing properties combined with infection control.

Key Properties of a Bioactive Ag-SiO2/TiO2 Coating on NiTi Shape Memory Alloy as Necessary at the Development of a New Class of Biomedical Materials

Recent years have seen the dynamic development of methods for functionalizing the surface of implants using biomaterials that can mimic the physical and mechanical nature of native tissue, prevent the formation of bacterial biofilm, promote osteoconduction, and have the ability to sustain cell proliferation. One of the concepts for achieving this goal, which is presented in this work, is to functionalize the surface of NiTi shape memory alloy by an atypical glass-like nanocomposite that consists of SiO2-TiO2 with silver nanoparticles. However, determining the potential medical uses of bio(nano)coating prepared in this way requires an analysis of its surface roughness, tribology, or wettability, especially in the context of the commonly used reference coat-forming hydroxyapatite (HAp). According to our results, the surface roughness ranged between (112 ± 3) nm (Ag-SiO2)-(141 ± 5) nm (HAp), the water contact angle was in the range (74.8 ± 1.6)° (Ag-SiO2)-(70.6 ± 1.2)° (HAp), while the surface free energy was in the range of 45.4 mJ/m2 (Ag-SiO2)-46.8 mJ/m2 (HAp). The adhesive force and friction coefficient were determined to be 1.04 (Ag-SiO2)-1.14 (HAp) and 0.247 ± 0.012 (Ag-SiO2) and 0.397 ± 0.034 (HAp), respectively. The chemical data showed that the release of the metal, mainly Ni from the covered NiTi substrate or Ag from Ag-SiO2 coating had a negligible effect. It was revealed that the NiTi alloy that was coated with Ag-SiO2 did not favor the formation of E. coli or S. aureus biofilm compared to the HAp-coated alloy. Moreover, both approaches to surface functionalization indicated good viability of the normal human dermal fibroblast and osteoblast cells and confirmed the high osteoconductive features of the biomaterial. The similarities of both types of coat-forming materials indicate an excellent potential of the silver-silica composite as a new material for the functionalization of the surface of a biomaterial and the development of a new type of functionalized implants.

Direct detection of microorganisms in sonicated orthopedic devices after in vitro biofilm production and different processing conditions

BACKGROUND

The gold standard for microbial detection in prosthetic joint infections is the multiple culture of the peri-prosthetic tissue. The fluid cultures after sonication can improve the recovery of the microorganisms.

OBJECTIVE

The aim of this study was to evaluate the sonication technique with a plastic bag and the effect of refrigeration on microorganism detection with conventional culturing, MALDI-TOF MS and qPCR assay on an orthopedic screw model.

METHODS

We produced biofilms of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans on orthopedic screws, which were stored under different conditions and temperatures before sonication. After sonication, the mass spectrometry by MALDI-TOF, qPCR and culture protocols was performed using the sonicated fluid, for detecting the microorganisms involved in the biofilm.

RESULTS

The bacterial bioburden decreased by approximately one log after the refrigeration period, in the screws containing P. aeruginosa and S. aureus biofilms. All the microorganisms involved in the screw biofilms were detected with MALDI-TOF and qPCR. Significant reductions in CFU counts occurred only in groups stored in the plastic bag, indicating that changes in temperature and humidity may favor cell death. However, this variation is not important for this model as it did not affect the detection owing to the high counts obtained.

CONCLUSION

Microbial identification by MALDI-TOF in sonicated fluid is feasible. With qPCR, there were no differences between the detection in the screws processed immediately or after refrigeration. It is necessary to consider whether or not the refrigeration period would affect microbial recovery in an explanted prosthesis.

Emerging Strategies to Combat β-Lactamase Producing ESKAPE Pathogens

Since the discovery of penicillin by Alexander Fleming in 1929 as a therapeutic agent against staphylococci, β-lactam antibiotics (BLAs) remained the most successful antibiotic classes against the majority of bacterial strains, reaching a percentage of 65% of all medical prescriptions. Unfortunately, the emergence and diversification of β-lactamases pose indefinite health issues, limiting the clinical effectiveness of all current BLAs. One solution is to develop β-lactamase inhibitors (BLIs) capable of restoring the activity of β-lactam drugs. In this review, we will briefly present the older and new BLAs classes, their mechanisms of action, and an update of the BLIs capable of restoring the activity of β-lactam drugs against ESKAPE (Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pathogens. Subsequently, we will discuss several promising alternative approaches such as bacteriophages, antimicrobial peptides, nanoparticles, CRISPR (clustered regularly interspaced short palindromic repeats) cas technology, or vaccination developed to limit antimicrobial resistance in this endless fight against Gram-negative pathogens.

Preparation of a New Biocomposite Designed for Cartilage Grafting with Antibiofilm Activity

New polymer–inorganic composites with antibiofilm features based on the granulated poly(tetrafluoroethylene) (PTFE) and apatite materials were obtained using a standard hydraulic press. The study was performed in hydroxy- and fluorapatites doped with different amounts of silver ions and followed by heat treatment at 600 °C. The structural, morphological, and physicochemical properties were determined by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy-energy-dispersive spectrometry (SEM-EDS), and transition electron microscopy (TEM). The antibacterial properties of the obtained materials were evaluated against Gram-negative pathogens such as Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli as well as against Gram-positive bacteria Staphylococcus epidermidis. The cytotoxicity assessment was carried out on the red blood cells (RBC) as a cell model for in vitro study. Moreover, the biofilm formation on the biocomposite surface was studied using confocal laser scanning microscopy (CLSM).

Recent Advances in Metal Decorated Nanomaterials and Their Various Biological Applications: A Review

Nanoparticles (nanoparticles) have received much attention in biological application because of their unique physicochemical properties. The metal- and metal oxide-supported nanomaterials have shown significant therapeutic effect in medical science. The mechanisms related to the interaction of nanoparticles with animal and plant cells can be used to establish its significant role and to improve their activity in health and medical applications. Various attempts have been made to discuss the antibiotic resistance and antimicrobial activity of metal-supported nanoparticles. Despite all these developments, there is still a need to investigate their performance to overcome modern challenges. In this regard, the present review examines the role of various types of metal-supported nanomaterials in different areas such as antibacterial, antifungal, anticancer, and so on. Based on the significant ongoing research and applications, it is expected that metal-supported nanomaterials play an outstanding role not only in medical but also in other important areas.

Metal-Based Nanostructures/PLGA Nanocomposites: Antimicrobial Activity, Cytotoxicity, and Their Biomedical Applications

Among the different synthetic polymers developed for biomedical applications, poly(lactic-co-glycolic acid) (PLGA) has attracted considerable attention because of its excellent biocompatibility and biodegradability. Nanocomposites based on PLGA and metal-based nanostructures (MNSs) have been employed extensively as an efficient strategy to improve the structural and functional properties of PLGA polymer. The MNSs have been used to impart new properties to PLGA, such as antimicrobial properties and labeling. In the present review, the different strategies available for the fabrication of MNS/PLGA nanocomposites and their applications in the biomedical field will be discussed, beginning with a description of the preparation routes, antimicrobial activity, and cytotoxicity concerns of MNS/PLGA nanocomposites. The biomedical applications of these nanocomposites, such as carriers and scaffolds in tissue regeneration and other therapies are subsequently reviewed. In addition, the potential advantages of using MNS/PLGA nanocomposites in treatment illnesses are analyzed based on in vitro and in vivo studies, to support the potential of these nanocomposites in future research in the biomedical field.

Mechanistic Insights into the Antimicrobial Actions of Metallic Nanoparticles and Their Implications for Multidrug Resistance

Multiple drug-resistant bacteria are a severe and growing public health concern. Because relatively few antibiotics have been approved over recent years and because of the inability of existing antibiotics to combat bacterial infections fully, demand for unconventional biocides is intense. Metallic nanoparticles (NPs) offer a novel potential means of fighting bacteria. Although metallic NPs exert their effects through membrane protein damage, superoxide radicals and the generation of ions that interfere with the cell granules leading to the formation of condensed particles, their antimicrobial potential, and mechanisms of action are still debated. This article discusses the action of metallic NPs as antibacterial agents, their mechanism of action, and their effect on bacterial drug resistance. Based on encouraging data about the antibacterial effects of NP/antibiotic combinations, we propose that this concept be thoroughly researched to identify means of combating drug-resistant bacteria.

Acitretin modulates HaCaT cells proliferation through STAT1- and STAT3-dependent signaling

Acitretin has been a valuable option for the treatment of psoriasis, however, the molecular events of acitretin leading to the normalization of keratinocytes differentiation on psoriasis patients have not been fully explored. To investigate whether there were certain relationship between keratinocytes proliferation and JAK/STAT signaling pathways in psoriasis, and how acitretin modulated the signaling pathways. HaCaT cells, an in vitro immortal human keratinocyte cell line, was chosen as a in vitro model of psoriasis. The small interfering RNA targeting STAT1 (siRNA-STAT1) and STAT3 (siRNA-STAT3) were subsequently transfected into the HaCaT cells which were treated with or without acitretin. We found that HaCaT cells proliferation and the expression of STAT1 or STAT3 were inhibited by acitretin, siRNA-STAT1 and siRNA-STAT3. Our experimental data shows that acitretin might inhibit HaCaT cells proliferation in psoriasis by decreasing the expression of STAT- and STAT3-dependent mechanism.

The comparative study of clinical efficacy and safety of baclofen vs tolperisone in spasticity caused by spinal cord injury

In the present study we compared the clinical efficacy and safety of baclofen vs tolperisone in spasticity caused by spinal cord injury. A total of 150 patients were enrolled in the present study and were divided into two groups with 75 patients in each group, receiving baclofen or tolperisone, respectively. We used Modified Ashworth Scale, Medical research council scale, Barthel Index, and Coefficient of efficacy to measure clinical efficacy. After 6-week treatment, both groups demonstrated significant improvement in muscle tone, muscle strength and functional outcome (Group I, 1.55 ± 0.053, 2.79 ± 0.032, 59.31 ± 1.32; Group II, 1.57 ± 0.053, 3.04 ± 0.032, 73 ± 1.32 respectively). There was no significant difference regarding improvement in muscle tone and muscle strength between the two groups (Group I, 1.055 ± 0.053 vs Group II, 1.57 ± 0.053; Group I, 2.79 ± 0.032 vs Group II, 3.04 ± 0.032, p > 0.05). However, the improvement in functional outcomes was greater in group II as compared to that in group I (Group I, 59.31 ± 1.32 vs Group II, 73 ± 1.32, p < 0.05). In addition, overall efficacy coefficient was greater for group II as compared to group I (Group I, 3.6 vs Group II, 2.3, p < 0.05). Group I had more side effects compared to Group II. Compared to baclofen, tolperisone offers greater improvement in activities of daily living compared to baclofen.

Effect of Motherwort total alkaloids on the prostate hyperplasia mice model of pathological changes of related tissue morphology induced by the fetal urogenital sinus implants

Aim

The research was to study the effect of Motherwort total alkaloids on the prostate hyperplasia mice model of pathological changes of related tissue morphology.

Results

Compared with the model group(MG), Motherwort total alkaloid high, medium dose group(HD, MD) could significantly reduced the pathological changes of the prostate (P < 0.01); Finasteride(FG) and Motherwort total alkaloid low dose group(LD) could significantly reduce the pathological changes of the prostate (P < 0.05); Longbishu capsules(LG), Finasteride, Motherwort total alkaloid medium dose group could significantly reduce the pathological changes of the kidney (P < 0.01); Motherwort total alkaloid low dose group could significantly reduce the pathological changes of the kidney (P < 0.05); Motherwort total alkaloids could improve the pathological changes of the thymus and spleen.

Conclusion

Motherwort total alkaloid can improve the pathological changes of prostatic hyperplasia in mice.

Effects of the Rabdosia rubescens total flavonoids on focal cerebral ischemia reperfusion model in rats

The effect of the Rabdosia rubescens total flavonoids on focal cerebral ischemia reperfusion model in rats was observed. The model group, nimodipine group, cerebral collateral group, and large, medium and small dose group of the Rabdosia rubescens total flavonoids were administered with corresponding drugs but sham operation group and model group were administered the same volume of 0.5%CMC, 1 times a day, continuous administration of 7 d. After 1 h at 7 d to medicine, left incision in the middle of the neck of rats after anesthesia, we can firstly expose and isolate the left common carotid artery (CCA), and then expose external carotid artery (ECA) and internal carotid artery (ICA). The common carotid artery and the external carotid artery are ligated. Then internal carotid artery with arterial clamp is temporarily clipped. Besides, cut the incision of 0.2 mm from 5 cm of the bifurcation of the common carotid artery. A thread Line bolt is inserted with more than 18-20 mm from bifurcation of CCA into the internal carotid artery until there is resistance. Then the entrance of the middle cerebral artery is blocked and internal carotid artery is ligated (the blank group only exposed the left blood vessel without Plugging wire). Finally it is gently pulled out the plug line after 2 h. Results: Compared with the model mice, Rabdosia rubescens total flavonoids can significantly relieve the injury of brain in hippocampus and cortex nerve cells; experimental rat focal cerebral ischemia was to improve again perfusion model of nerve function defect score mortality; significantly reduce brain homogenate NOS activity and no content, MDA, IL-1, TNF-a, ICAM-1 content; increase in brain homogenate SOD and ATPase activity (P < 0.05, P < 0.01); and reduce the serum S-100β protein content. Each dose group of the Rabdosia rubescens total flavonoids has a better Improvement effect on focal cerebral ischemia reperfusion model in rats.

The effects of low-molecular-weight heparin on lung and pulmonary artery injuries in acute pulmonary embolism rat model via platelet-derived growth factor-β

Objective

To evaluate the effects of anticoagulant agent (low-molecular-weight heparin, LMWH) on the pulmonary artery intima hyperplasia of rats with acute pulmonary embolism (APE) by assaying platelet-derived growth factor-β (PDGF-β).

Methods

A total of 90 Sprague-Dawley rats were randomly assigned into the sham, APE, and LMWH groups with 30 rats in each group. The APE rat models were established by injecting autologous blood clots via external jugular veins. In each group, six mice were sacrificed at the 1st day (D1), 4th day (D4), 7th day (D7), 14th day (D14), and 28th (D28) subsequent to the induction of APE to collect the lungs. Right ventricle pressure (RVP) and mean pulmonary arterial pressure (mPAP) were measured. Western blot and RT-PCR analyses were used to assess PDGF-β expression at various time points. In addition, changes in lung pathology were evaluated using hematoxylin and eosin (H&E) staining and electron microscope.

Results

The overall success rate of establishing APE rat models was 85.7% (60/70). There was no difference in mPAP between the sham group and the APE group at the D1, D4, D7, and D14. However, at the D28, mPAP in the APE group was significantly higher than that in the sham group. There was no difference among the three groups regarding RVP. PDGF-β expression were decreased in the LMWH group at all time points compared with the sham and APE groups (P < 0.01). Furthermore, pulmonary embolism, alveolar wall necrosis and hemorrhage, and inflammation were significantly attenuated in the LMWH group compared with the sham and APE groups subsequent to the induction of APE.

Conclusion

LMWH attenuates lung and pulmonary artery injuries and improves prognosis. Decreased PDGF-β in the lungs may be the important factor in the effects observed.

The influence of connective tissue growth factor on rabbit ligament injury repair

Objectives

The injured anterior cruciate ligament (ACL) is deemed to exhibit an impaired healing response and attempts at surgical repair have not been successful. Connective tissue growth factor (CTGF) is reported to be associated with wound healing, probably through transforming growth factor beta1 (TGF-β1).

Methods

A rabbit ACL injury model was used to study the effect of CTGF on ligament recovery. Quantitative real-time PCR was performed for detection of changes in RNA levels of TGF-β1, type 1 collagen (COL-I), type 2 collagen (COL-II), SRY-related high mobility group-box gene9 (Sox9), metalloproteinase-1 (TIMP-1) as well as matrix metallopeptidase 13 (MMP-13). And expression of related proteins was detected by western blotting.

Results

The current study showed that CTGF could promote the recovery of inured anterior cruciate ligament. It can up-regulate the mRNA and expression of TGF-β1, COL-I, COL-II, Sox9, as well as the tissue inhibitor of TIMP-1, and down-regulated the mRNA and expression of MMP-13, suggesting the curative effect of CTGF on injured rabbit ligament is through regulating these cellular factors.

Conclusion

This finding revealed the mechanism of CTFG’s healing role in injured tissues and provided new possibilities of treating injured tissues and wound healing by using CTFG.

Impacts of triamcinolone acetonide on femoral head chondrocytic structures in lumbosacral plexus block

Objective: To investigate impacts of triamcinolone acetonide (TRI) on femoral head chondrocytic (FHC) structures when used for lumbosacral plexus block (LPB). Methods: A total of 32 6-month-old New Zealand white rabbits were selected (averagely weighing 2.75–3.25 kg) and added TRI into nerve block solution for LPB. The rabbit were randomly divided into four groups: group A1: 2.5 ml × 2 times, group A2 2.5 ml × 4 times, group B1 5 ml × 2 times, and group B2 5 ml × 4 times; the time interval among the injection was 5 days, and the structural changes of FHC were the observed using 50/100/200 light microscope; the modified Mankin pathological scoring was also performed for the evaluation. Results: There exhibited significant microscopic changes of FHC structures between the rabbits performed LPB and the normal rabbits, among which group B2 exhibited the most serious FHC damages, and the Mankin pathological score in group B2 was much higher than those in the other three groups, and the scores of the experimental group were higher than the control group. Conclusions: The addition of TRI in LPB can damage the FHC structures, and large-dose (5 ml/once) and long-course (four times) will result in more serious injuries.

Investigation on the immunomodulatory activities of Sarcodon imbricatus extracts in a cyclophosphamide (CTX)-induced immunosuppressanted mouse model

Aims: Sarcodon imbricatus, an edible fungus, is widely used in Asian medicine because of its significant pharmacological activities. In the present study, we investigated the immunomodulatory effects of polysaccharide-enriched S. imbricatus extracts (SP) in cyclophosphamide (CTX)-induced immunosuppressed mice. Results: Astragalus polysaccharide (AP) was used as a positive control. Compared with CTX-induced immunosuppressed mice, thirty-day SP treatment strongly enhanced the organ indexes of spleen and thymus and suppressed hind paw swelling. Both AP and SP increased the serum levels of immunoglobulin (IgA, IgG, and IgM), and suppressed the overproduction of interleukin-2 (IL-2). Moreover, SP reduced methane dicarboxylic aldehyde levels, and increased the total antioxidant capacity, superoxide dismutase, and glutathione peroxidase in both serum and liver tissues of CTX-induced immunosuppressed mice. Conclusion: S. imbricatus extracts significantly improved immune function in CTX-induced immunosuppressed mice via modulation of oxidative systems.

The antimicrobial activity of nanoparticles: present situation and prospects for the future

Nanoparticles (NPs) are increasingly used to target bacteria as an alternative to antibiotics. Nanotechnology may be particularly advantageous in treating bacterial infections. Examples include the utilization of NPs in antibacterial coatings for implantable devices and medicinal materials to prevent infection and promote wound healing, in antibiotic delivery systems to treat disease, in bacterial detection systems to generate microbial diagnostics, and in antibacterial vaccines to control bacterial infections. The antibacterial mechanisms of NPs are poorly understood, but the currently accepted mechanisms include oxidative stress induction, metal ion release, and non-oxidative mechanisms. The multiple simultaneous mechanisms of action against microbes would require multiple simultaneous gene mutations in the same bacterial cell for antibacterial resistance to develop; therefore, it is difficult for bacterial cells to become resistant to NPs. In this review, we discuss the antibacterial mechanisms of NPs against bacteria and the factors that are involved. The limitations of current research are also discussed.