Antibacterial and cytotoxic assessment of poly (methyl methacrylate) based hybrid nanocomposites

Incorporating versus coating antimicrobials for polymethyl methacrylate: A systematic review

STATEMENT OF PROBLEM

Incorporating and coating with antimicrobials are techniques that can confer antimicrobial action on polymethyl methacrylate (PMMA) denture bases, which can accumulate microorganisms and promote oral and systemic disease.

PURPOSE

The purpose of this systematic review was to answer the question: "Do techniques for incorporating and coating antimicrobial agents in PMMA promote antimicrobial action?"

MATERIAL AND METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist guidelines were followed, and the SCOPUS, PubMed/Medline, EMBASE, and Science Direct databases searched. The studies were selected in 2 stages, reading the titles and abstracts and then reading the selected studies in full. The risk of bias was analyzed by adapting the quasi-experimental studies tool by the Joanna Briggs Institute (JBI).

RESULTS

A total of 970 articles were found in the databases; 71 were duplicates and, after reading the abstracts, 38 were selected for full reading. From these, 6 were excluded because they did not fulfill the inclusion criteria, and 32 studies were included in this review. Autopolymerizing, heat- polymerizing, and light-polymerizing resins were evaluated, with the incorporating technique prevailing over the coating, but both techniques effectively promoted antimicrobial activity.

CONCLUSIONS

Incorporating and coating antimicrobial agents are effective methods of promoting antimicrobial activity in PMMA. Combining the 2 methods led to increased antimicrobial activity compared with each individually.

Janus silk fibroin/polycaprolactone-based scaffold with directionally aligned fibers and porous structure for bone regeneration

To promote bone repair, it is desirable to develop three-dimensional multifunctional fiber scaffolds. The densely stacked and tightly arranged conventional two-dimensional electrospun fibers hinder cell penetration into the scaffold. Most of the existing three-dimensional structural materials are isotropic and monofunctional. In this research, a Janus nanofibrous scaffold based on silk fibroin/polycaprolactone (SF/PCL) was fabricated. SF-encapsulated SeNPs demonstrated stability and resistance to aggregation. The outside layer (SF/PCL/Se) of the Janus nanofiber scaffold displayed a structured arrangement of fibers, facilitating cell growth guidance and impeding cell invasion. The inside layer (SF/PCL/HA) featured a porous structure fostering cell adhesion. The Janus fiber scaffold containing SeNPs notably suppressed S. aureus and E. coli activities, correlating with SeNPs concentration. In vitro, findings indicated considerable enhancement in alkaline phosphatase (ALP) activity of MC3T3-E1 osteoblasts and upregulation of genes linked to osteogenic differentiation with exposure to the SF/PCL/HA/Se Janus nanofibrous scaffold. Moreover, in vivo, experiments demonstrated successful critical bone defect repair in mouse skulls using the SF/PCL/HA/Se Janus nanofiber scaffold. These findings highlight the potential of the SF/PCL-based Janus nanofibrous scaffold, integrating SeNPs and nHA, as a promising biomaterial in bone tissue engineering.

Antibacterial and Cytotoxic Study of Hybrid Films Based on Polypropylene and NiO or NiFe2O4 Nanoparticles

This study presents an in vitro analysis of the bactericidal and cytotoxic properties of hybrid films containing nickel oxide (NiO) and nickel ferrite (NiFe2O4) nanoparticles embedded in polypropylene (PP). The solvent casting method was used to synthesize films of PP, PP@NiO, and PP@NiFe2O4, which were characterized by different spectroscopic and microscopic techniques. The X-ray diffraction (XRD) patterns confirmed that the small crystallite sizes of NiO and NiFe2O4 NPs were maintained even after they were incorporated into the PP matrix. From the Raman scattering spectroscopy data, it was evident that there was a significant interaction between the NPs and the PP matrix. Additionally, the Scanning Electron Microscopy (SEM) analysis revealed a homogeneous dispersion of NiO and NiFe2O4 NPs throughout the PP matrix. The incorporation of the NPs was observed to alter the surface roughness of the films; this behavior was studied by atomic force microscopy (AFM). The antibacterial properties of all films were evaluated against Pseudomonas aeruginosa (ATCC®: 43636™) and Staphylococcus aureus (ATCC®: 23235™), two opportunistic and nosocomial pathogens. The PP@NiO and PP@ NiFe2O4 films showed over 90% bacterial growth inhibition for both strains. Additionally, the effects of the films on human skin cells, such as epidermal keratinocytes and dermal fibroblasts, were evaluated for cytotoxicity. The PP, PP@NiO, and PP@NiFe2O4 films were nontoxic to human keratinocytes. Furthermore, compared to the PP film, improved biocompatibility of the PP@NiFe2O4 film with human fibroblasts was observed. The methodology utilized in this study allows for the production of hybrid films that can inhibit the growth of Gram-positive bacteria, such as S. aureus, and Gram-negative bacteria, such as P. aeruginosa. These films have potential as coating materials to prevent bacterial proliferation on surfaces.

Gum Arabic polysaccharide embedded L-cysteine capped copper oxide nanocarriers selectively inhibit fluconazole-resistant C. albicans biofilm and remove the toxic dye from wastewater

Copper oxide nanocarriers have attracted increasing interest in the scientific community, including antimicrobial applications. Candida biofilm developed causes serious clinical problems, leading to drug failure caused by its inherent drug tolerance. Nanocarriers are a good alternative approach to solving this challenge because of their excellent penetration power inside biofilms. Hence, main objectives of this research were to prepare gum arabic-embedded L-cysteine-capped copper oxide nanocarriers (GCCuO NCs) and tested against C. albicans and explore another application. To achieve the main research objectives, GCCuO NCs were synthesized and investigated for antibiofilm potency against C. albicans. Various methods were employed to measure antibiofilm potency such as biofilm assay etc., of NCs. The nano size of GCCuO NCs is advantageous for augmenting penetration power and retention into biofilms. GCCuO NCs at 100 μg/mL exhibited significant antibiofilm activity against the C. albicans DAY185 by switching of yeast-to-hyphae and gene perturbation. The level of CR dye adsorption was 58.96 % using 30 μg/mL of NCs. Based on effective C. albicans biofilm inhibition and CR dye adsorption capacity of NCs, it can be suggested that present research work opens an innovative path to treat biofilm-associated fungal infections, and these NCs can be used for environmental remedies.

In vitro toxicity of naringin and berberine alone, and encapsulated within PMMA nanoparticles

Phytochemical compounds, such as naringin and berberine, have been used for many years due to their antioxidant activities, and consequently, beneficial health effects. In this study, it was aimed to evaluate the antioxidant properties of naringin, berberine and poly(methylmethacrylate) (PMMA) nanoparticles (NPs) encapsulated with naringin or berberine and their possible cytotoxic, genotoxic, and apoptotic effects on mouse fibroblast (NIH/3 T3) and colon cancer (Caco-2) cells. According to the results of the study, it was found that the 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition antioxidant activity of naringin, berberine, and naringin or berberine encapsulated PMMA NPs, was significantly increased at higher tested concentrations due to the antioxidant effects of naringin, berberine and naringin or berberine encapsulated PMMA NPs. As a result of the cytotoxicity assay, after 24-, 48- and 72-h of exposure, all of the studied compounds caused cytotoxic effects in both cell lines. Genotoxic effects of studied compounds were not registered at lower tested concentrations. Based on these data, polymeric nanoparticles encapsulated with naringin or berberine may contribute to new treatment approaches for cancer, but further in vivo and in vitro research is required.

Novel Microwave Synthesis of Copper Oxide Nanoparticles and Appraisal of the Antibacterial Application

The exceptional characteristics of bio-synthesized copper oxide nanoparticles (CuO NPs), including high surface-to-volume ratio and high-profit strength, are of tremendous interest. CuO NPs have cytotoxic, catalytic, antibacterial, and antioxidant properties. Fruit peel extract has been recommended as a valuable alternative method due to the advantages of economic prospects, environment-friendliness, improved biocompatibility, and high biological activities, such as antioxidant and antimicrobial activities, as many physical and chemical methods have been applied to synthesize metal oxide NPs. In the presence of apple peel extract and microwave (MW) irradiation, CuO NPs are produced from the precursor CuCl₂. 2H₂O. With the help of TEM analysis, and BET surface area, the average sizes of the obtained NPs are found to be 25-40 nm. For use in antimicrobial applications, CuO NPs are appropriate. Disk diffusion tests were used to study the bactericidal impact in relation to the diameter of the inhibition zone, and an intriguing antibacterial activity was confirmed on both the Gram-positive bacterial pathogen Staphylococcus aureus and Gram-negative bacterial pathogen Escherichia coli. Moreover, CuO NPs did not have any toxic effect on seed germination. Thus, this study provides an environmentally friendly material and provides a variety of advantages for biomedical applications and environmental applications.

One Pot Synthesis of Copper Oxide Nanoparticles for Efficient Antibacterial Activity

The unique semiconductor and optical properties of copper oxides have attracted researchers for decades. However, using fruit waste materials such as peels to synthesize the nanoparticles of copper oxide (CuO NPs) has been rarely described in literature reviews. The main purpose of this part of the research was to report on the CuO NPs with the help of apple peel extract under microwave irradiation. Metal salts and extracts were irradiated at 540 W for 5 min in a microwave in a 1:2 ratio. The crystallinity of the NPs was confirmed by the XRD patterns and the crystallite size of the NPs was found to be 41.6 nm. Elemental mapping of NPs showed homogeneous distributions of Cu and O. The NPs were found to contain Cu and O by EDX and XPS analysis. In a test involving two human pathogenic microbes, NPs showed antibacterial activity and the results revealed that the zone of inhibition grew significantly with respect to the concentration of CuO NPs. In a biofilm, more specifically, NPs at 25.0 µg/mL reduced mean thickness and biomass values of S. aureus and E. coli biofilms by >85.0 and 65.0%, respectively, with respect to untreated controls. In addition, environmentally benign materials offer a number of benefits for pharmaceuticals and other biomedical applications as they are eco-friendly and compatible.

Bacterial Response to the Surface Aging of PLA Matrices Loaded with Active Compounds

The use of active components in biomaterials improves the properties of existing ones and makes it possible to obtain new devices with antibacterial properties that prevent infections after implantation, thus guaranteeing the success of the implant. In this work, cetyltrimethylammonium bromide (CTAB) and magnesium particles were incorporated into polylactic acid (PLA) films to assess the extent to which progressive aging of the new surfaces resists bacterial colonization processes. For this purpose, the films' surface was characterized by contact angle measurements, ToF-SIMS and AFM, and adhesion, viability and biofilm growth of Staphylococcus epidermidis bacteria on these films were also evaluated. The results show that the inclusion of Mg and CTAB in PLA films changes their surface properties both before and after aging and also modifies bacterial adhesion on the polymer. Complete bactericidal activity is exhibited on non-degraded films and films with CTAB. This antibacterial behavior is maintained after degradation for three months in the case of films containing a higher amount of CTAB.

Antibiotic-free antimicrobial poly (methyl methacrylate) bone cements: A state-of-the-art review

Prosthetic joint infection (PJI) is the most serious complication following total joint arthroplasty, this being because it is associated with, among other things, high morbidity and low quality of life, is difficult to prevent, and is very challenging to treat/manage. The many shortcomings of antibiotic-loaded poly (methyl methacrylate) (PMMA) bone cement (ALBC) as an agent for preventing and treating/managing PJI are well-known. One is that microorganisms responsible for most PJI cases, such as methicillin-resistant S. aureus, have developed or are developing resistance to gentamicin sulfate, which is the antibiotic in the vast majority of approved ALBC brands. This has led to many research efforts to develop cements that do not contain gentamicin (or, for that matter, any antibiotic) but demonstrate excellent antimicrobial efficacy. There is a sizeable body of literature on these so-called "antibiotic-free antimicrobial" PMMA bone cements (AFAMBCs). The present work is a comprehensive and critical review of this body. In addition to summaries of key trends in results of characterization studies of AFAMBCs, the attractive features and shortcomings of the literature are highlighted. Shortcomings provide motivation for future work, with some ideas being formulation of a new generation of AFAMBCs by, example, adding a nanostructured material and/or an extract from a natural product to the powder and/or liquid of the basis cement, respectively.

Novel polymethyl methacrylate modified with metal methacrylate monomers: biological, physicomechanical, and optical properties

This study sought to evaluate the physical and antimicrobial properties of a thermopolymerizable acrylic resin (PMMA) modified with metallic methacrylate monomers -zirconia (ZM), tin (TM), and di-n-butyl (DNTMB) methacrylates. Color stability was evaluated before and after immersion of samples in a staining solution by a digital spectrophotometer. The mechanical brushing test was evaluated by the roughness test. The flexural strength test used a mechanical testing machine. Human keratinocytes were used to assess cell viability and the biofilm formation assay was carried out for 5 days, in a microcosms model after one year of specimen storage. For statistical analysis, the method chosen was based on adherence to the normal distribution model and equality of variances (p < 0.05). The addition of DNTMB to PMMA promoted great antimicrobial action, acceptable cytocompatibility, without hampering the physical-mechanical properties of the commercial material. Therefore, the modified PMMA proved to be a promisor alternative to conventional resins.This study sought to evaluate the physical and antimicrobial properties of a thermopolymerizable acrylic resin (PMMA) modified with metallic methacrylate monomers -zirconia (ZM), tin (TM), and di-n-butyldimethacrylate-tin (DNTMB) methacrylates. Color stability was evaluated before and after immersion of samples in a staining solution using a digital spectrophotometer. The mechanical brushing test was evaluated by the roughness test. The flexural strength test used a mechanical testing machine. Human keratinocytes were used to assess cell viability and the biofilm formation assay was carried out for 5 days in a microcosm model after one year of specimen storage. For statistical analysis, the method chosen was based on adherence to the normal distribution model and equality of variances (p < 0.05). The addition of DNTMB to PMMA promoted great antimicrobial action, acceptable cytocompatibility, without hampering the physical-mechanical properties of the commercial material. Therefore, the modified PMMA proved to be a promising alternative to conventional denture base resins for dental use.

Mechanical properties of new denture base material modified with gold nanoparticles

PURPOSE

Poly(methyl methacrylate) (PMMA) is the most commonly used material in the production of dental prostheses, and its application is often accompanied by the formation of biofilm. The aim of this work was the preparation of a PMMA/gold nanoparticles (AuNps) composite to improve the antimicrobial properties of heat-polymerised PMMA. The AuNPs were synthesised from gold (III) acetate by Ultrasonic Spray Pyrolysis (USP).In the present study, flexural strength and elastic modulus were investigated, as well as thermal conductivity, density and hardness of the PMMA/AuNps` nanocomposite, with different concentrations of AuNps. Flexural strength and elastic modulus were measured using a three-point bending test, and surface hardness was evaluated using the Vickers hardness test. The thermal conductivity of the samples was measured using the Transient Plane Source (TPS) technique. Density was determined by the pycnometry procedure. Statistical analysis was conducted on the data obtained from the experiments.

RESULTS

The flexural strength and elastic modulus of AuNps/PMMA nanocomposites decreased for all groups containing AuNps. Thermal conductivity and density increased in all groups containing AuNps compared to the control group, but it was not significant in all groups. Vickers hardness values increased significantly with an increase in AuNps` content, with the highest value 21.45 HV obtained at 0.74 wt% of AuNps. Statistical analysis was performed by means of the SPSS 19 software package.

CONCLUSIONS

Incorporation of AuNps into heat-polymerised PMMA resin led to decrease of the flexural strength and elastic modulus. At the same time, the density, thermal conductivity and hardness increased.

Acute Mastoiditis With Intracranial Complications in a Young Adult With History of Cranioplasty: The Rule in the Post-Antibiotic Era

The presentation of acute mastoiditis has become erratic over the last decades secondary to the wide use of broad-spectrum antibiotics. While establishing this diagnosis requires a high degree of suspicion, imaging is necessary because of the concurrence of intracranial complications. Therefore, the diagnostic hypothesis of acute mastoiditis must prompt the evaluation for the presence of intracranial complications, such as intracranial epidural abscess (ICEA) formation. Hereby, we present a case of a 33-year-old woman presented to the ED of our institution with symptoms consistent with acute mastoiditis. She had a history of a methyl-methacrylate (MMA) cranioplasty performed 10 years before presentation for debulking of an epidermoid cyst. She was found to have the formation of an ICEA. Development of infection in patients with MMA cranioplasty is seen most commonly within one year of the implantation with the late presentation being a rare occurrence. Treatment in these cases is comprised of antibiotic therapy, but most importantly of the removal of the infected foreign material to prevent further complications from the infection.

Microstructure Characterisation and Identification of the Mechanical and Functional Properties of a New PMMA-ZnO Composite

In this research work, we synthesised poly(methyl methacrylate) (PMMA) enriched with 2 wt.% zinc oxide nanoparticles (ZnO) through conventional heat polymerisation and characterised its microstructure. It was found that the distribution of ZnO nanoparticles was homogeneous through the volume of the PMMA. The mechanical testing of the PMMA-ZnO composite primarily included the determination of the compressive properties on real dentures, while density measurements were performed using a pycnometer. The testing of functional properties involved the identification of the colour of the new PMMA-ZnO composite, where pure PMMA acted as a control. In the second step, the PMMA-ZnO cytotoxicity assays were measured in vitro, which were shown to be similar to the control PMMA. Based on this, it could be concluded that the newly formed PMMA-ZnO composite did not induce direct or indirect cytotoxic effects in L929 cell cultures; therefore, according to ISO/DIN 10993-5:2009, this composite was categorised as non-cytotoxic.

A dual PMMA/calcium sulfate carrier of vancomycin is more effective than PMMA-vancomycin at inhibiting Staphylococcus aureus growth in vitro

Both antibiotic-impregnated poly(methyl acrylate, methyl methacrylate) (PMMA) and antibiotic-impregnated calcium sulfate have been successfully used as local antibiotic delivery vehicles for the management of chronic osteomyelitis. Here, we examined the antibiotic elution characteristics and antibacterial properties of a composite drug delivery system consisting of PMMA/calcium sulfate carrying vancomycin (dual carrier-v) against Staphylococcus aureus, with PMMA loaded with vancomycin (PMMA-v) as a control. Vancomycin gradually degraded from dual carrier-v and PMMA-v up to about 8 and 6 weeks, respectively. At different elution time points, the inhibition zones of the dual carrier-v were larger than the inhibition zones of the PMMA-v (P < 0.05). The colony inhibition rate of the dual carrier-v was 95.57%, whereas it was 77.87% for PMMA-v. Scanning electron microscopy was used to demonstrate biofilm formation on the surface of plates treated with vancomycin-unloaded PMMA, whereas there was no biofilm formation on the surface of plates treated with dual carrier-v or PMMA-v. The dual carrier-v was more effective at antibacterial adhesion at each time point after immersion in simulated body fluid as compared with PMMA-v (P < 0.05). In conclusion, our results suggest that the dual carrier-v can release higher concentrations of antibiotics and inhibit bacteria growth more effectively in vitro as compared with PMMA-v. The dual carrier-v thus may have potential as an alternative strategy for osteomyelitis management.

Cytotoxicity, Antioxidant, Antibacterial, and Photocatalytic Activities of ZnO-CdS Powders

In this work, ZnO–CdS composite powders synthesized by a simple chemical precipitation method were thoroughly characterized. The morphological, structural, compositional, photocatalytical, and biological properties of the prepared composites were investigated in comparison with those of the pristine components and correlated with the CdS concentration. ZnO–CdS composites contain flower-like structures, their size being tuned by the CdS amount added during the chemical synthesis. The photocatalytic activity of the composites was analyzed under UV irradiation using powders impregnated with methylene blue; the tests confirming that the presence of CdS along the ZnO in composites can improve the dye discoloration. The biological properties such as antioxidant capacity, antibacterial activity, and cytotoxicity of the ZnO, CdS, and ZnO–CdS composites were evaluated. Thus, the obtained composites presented medium antioxidant effect, biocidal activity against Escherichia coli, and no toxicity (at concentrations less than 0.05 mg/mL for composites with a low CdS amount) for human fibroblast cells. Based on these results, such composites can be used as photocatalytic and/or biocidal additives for photoactive coatings, paints, or epoxy floors, which in their turn can provide a cleaner and healthier environment.

PMMA-Based Bone Cements and the Problem of Joint Arthroplasty Infections: Status and New Perspectives

Polymethyl methacrylate (PMMA)-based bone cement is a biomaterial that has been used over the last 50 years to stabilize hip and knee implants or as a bone filler. Although PMMA-based bone cement is widely used and allows a fast-primary fixation to the bone, it does not guarantee a mechanically and biologically stable interface with bone, and most of all it is prone to bacteria adhesion and infection development. In the 1970s, antibiotic-loaded bone cements were introduced to reduce the infection rate in arthroplasty; however, the efficiency of antibiotic-containing bone cement is still a debated issue. For these reasons, in recent years, the scientific community has investigated new approaches to impart antibacterial properties to PMMA bone cement. The aim of this review is to summarize the current status regarding antibiotic-loaded PMMA-based bone cements, fill the gap regarding the lack of data on antibacterial bone cement, and explore the progress of antibacterial bone cement formulations, focusing attention on the new perspectives. In particular, this review highlights the innovative study of composite bone cements containing inorganic antibacterial and bioactive phases, which are a fascinating alternative that can impart both osteointegration and antibacterial properties to PMMA-based bone cement.

Copper oxide nanoparticles as an effective anti-biofilm agent against a copper tolerant marine bacterium, Staphylococcus lentus

Biofilm formation on antifouling coatings is a serious concern in seawater cooling systems and the maritime industry. A prolific biofilm forming strain (Staphylococcus lentus), possessing high tolerance (>1,000 µg ml^-1) to dissolved copper ions (Cu⁺⁺) was isolated from titanium coupons exposed in the coastal waters of Kalpakkam, east coast of India. S. lentus formed increased biofilm (p < 0.05) at 100 µg ml^-1 of Cu⁺⁺ ions, when compared with the untreated control. To combat biofilm formation of this strain, the efficacy of copper oxide nanoparticles synthesized from copper nitrate by varying the concentrations of hexamine and cetyl trimethyl ammonium bromide (CTAB), was investigated. Complete (100%) inhibition of biofilm formation was observed with plain CuO NP (0.5 M hexamine, uncapped) at 1,000 µg ml^-1. Capping with CTAB, influenced the morphology and the purity of the synthesized CuO NPs but did not alter their surface charge. Capping reduced metal ion release from CuO NPs and their antibacterial and anti-biofilm property against S. lentus. Overall, uncapped CuO NPs were effective in controlling biofilm formation of S. lentus. Concurrent release of copper ions and contact mediated physical damage by CuO NPs offer a promising approach to tackle metal tolerant biofilm bacteria.