Trans-Cinnamaldehyde-Fighting Streptococcus mutans Using Nature.

Streptococcus mutans (S. mutans) is the main cariogenic bacterium with acidophilic properties, in part due to its acid-producing and -resistant properties. As a result of this activity, hard tooth structures may demineralize and form caries. Trans-cinnamaldehyde (TC) is a phytochemical from the cinnamon plant that has established antibacterial properties for Gram-positive and -negative bacteria. This research sought to assess the antibacterial and antibiofilm effects of trans-cinnamaldehyde on S. mutans. TC was diluted to a concentration range of 156.25-5000 µg/mL in dimethyl sulfoxide (DMSO) 0.03-1%, an organic solvent. Antibacterial activity was monitored by testing the range of TC concentrations on 24 h planktonic growth compared with untreated S. mutans. The subminimal bactericidal concentrations (MBCs) were used to evaluate the bacterial distribution and morphology in the biofilms. Our in vitro data established a TC MBC of 2500 µg/mL against planktonic S. mutans using a microplate spectrophotometer. Furthermore, the DMSO-only controls showed no antibacterial effect against planktonic S. mutans. Next, the sub-MBC doses exhibited antibiofilm action at TC doses of ≥625 µg/mL on hydroxyapatite discs, as demonstrated through biofilm analysis using spinning-disk confocal microscopy (SDCM) and high-resolution scanning electron microscopy (HR-SEM). Our findings show that TC possesses potent antibacterial and antibiofilm properties against S. mutans. Our data insinuate that the most effective sub-MBC of TC to bestow these activities is 625 µg/mL.

Antibacterial Orthodontic Adhesive Incorporating Polyethyleneimine Nanoparticles.

PURPOSE: To evaluate the antibacterial, mechanical and biocompatibility characteristics of an orthodontic adhesive that contains quaternary ammonium polyethyleneimine (QPEI) nanoparticles. MATERIALS AND METHODS: QPEI nanoparticles were added to an orthodontic adhesive at 0%, 1% and 1.5% wt/wt. Antibacterial activity was tested after aging for 14 days using the direct contact test (DCT). The degree of monomer conversion (DC) was measured using Fourier transform infrared (FTIR) spectroscopy. Shear bond atrength (SBS) was tested on the etched enamel of extracted human teeth. Biocompatibility was tested using keratinocyte and neutrophil cell lines in the XTT assay. RESULTS: The DCT results showed significant bacterial growth inhibition in the test group incorporating 1.5% wt/wt QPEI nanoparticles (p < 0.05). The DC of the 0%, 1%, and 1.5% wt/wt samples measured immediately and after 10 min was 62.2-71.0%, 59.1-68.7%, and 52.9-58.6%, respectively, and the average SBS were 9.25 MPa, 11.57 MPa, and 9.10 MPa, respectively. Keratinocyte and neutrophil viability did not change following the addition of QPEI to the orthodontic adhesives. CONCLUSIONS: The incorporation of QPEI nanoparticles into orthodontic cement provides long-lasting antibacterial activity against Streptococcus mutans without reducing the strength of adhesion to enamel, the degree of double bond conversion during the polymerisation, or the biocompatibility of the orthodontic cement.

Antibacterial effect of composite resin foundation material incorporating quaternary ammonium polyethyleneimine nanoparticles.

STATEMENT OF PROBLEM: As caries is the most frequent cause of the failure of composite resin-based restorations, composite resins with antibacterial properties are desirable. However, whether quaternary ammonium polyethyleneimine nanoparticles can be effectively incorporated is unknown. PURPOSE: The purpose of this in vitro study was to evaluate the antibacterial activity against Streptococcus mutans and Actinomyces viscosus of a foundation material incorporating quaternary ammonium polyethyleneimine (QPEI) nanoparticles. MATERIAL AND METHODS: QPEI antimicrobial nanoparticles were incorporated in a commercially available foundation material (Q Core; BJM Laboratories Ltd) at 1% wt/wt. Antibacterial efficacy against S mutans (106 colony-forming units [CFU]/mL) and A viscosus (106 CFU/mL) was examined by the direct contact test (DCT), and the agar diffusion test (ADT) with and without surface polishing. Bacterial outgrowth was recorded with a spectrophotometer. RESULTS: Growth of S mutans and A viscosus was inhibited, showing a decrease by 6 orders of magnitude in bacterial viability in specimens incorporating the nanoparticles, even after polishing the foundation material (P<.05). Growth inhibition was not observed in specimens without nanoparticles. CONCLUSIONS: Antibacterial properties can be achieved in a commercially available foundation material by incorporating polycationic antibacterial nanoparticles. This antibacterial effect did not diminish after surface polishing.

Synthesis variants of quaternary ammonium polyethyleneimine nanoparticles and their antibacterial efficacy in dental materials.

BACKGROUND: Resin-based dental materials allow bacterial growth on their surface and lack antibacterial activity, leading to functional and esthetic failure. Quaternary ammonium polyethyleneimine (QPEI) nanoparticles (NPs) incorporated in resin-based composite at 2% wt/wt have demonstrated prolonged and complete inhibition of bacterial growth. This study focused on optimization of QPEI NP synthesis to reduce the concentration required for bacterial growth inhibition. The objective here was to enhance antimicrobial efficacy by excess base neutralization, using phosphoric or hydrochloric acid, and by using surfactants. METHODS: QPEI NP variants were prepared (i) under controlled neutralization of acid, using NaHCO3, (ii) under controlled carbonate ion neutralization with HCl or H3PO4 and (iii) by treatment with N-lauroylsarcosine or glycerol monostearate. NPs incorporated in the dental materials were examined for their antibacterial effect against Enterococcus faecalis. RESULTS: Controlled addition of NaHCO3 resulted in modified QPEI NPs with an increased ability to inhibit bacterial growth. Surface treatment with N-lauroylsarcosine resulted in enhanced antibacterial activity at 0.5% wt/wt concentration in acrylate and epoxy resin-based dental materials. CONCLUSIONS: The antimicrobial efficacy of QPEI NP may be improved significantly by controlling the addition of NaHCO3, neutralization of excess base and the surface-agent effect.

Lethal bacterial trap: Cationic surface for endodontic sealing.

Insoluble antibacterial cationic nanoparticles have been previously shown to have potent and long-lasting antibacterial properties. Our tested hypothesis was that root canal pathogens will be attracted to and eliminated when exposed to epoxy resin-based surfaces incorporating cationic nanoparticles. In our research, an epoxy resin-based surface incorporating quaternary ammonium polyethyleneimine (QPEI) nanoparticles was evaluated. Surface characterization was performed using atomic force microscopy and X-ray photoelectron spectra. The surface anti-Enterococcus faecalis effect was evaluated in an anti-gravitational model. Cell membrane potential, viability, biofilm thickness, and biomass were tested using flow cytometry and confocal laser scanning microscopy. Additionally, the antibiofilm activity of the bacterial supernatant was assessed. The surface characterization showed QPEI nanoparticle embedment on the modified sealer. The epoxy resin-based surface incorporating the QPEI nanoparticles actively attracted bacteria, causing membrane destabilization, and bacterial death. The supernatant of bacteria pre-exposed to QPEI showed an antibacterial effect. In conclusion, the tested epoxy resin-based surface incorporating QPEI nanoparticles traps and kills bacteria. The nanoparticles attracted bacteria, reducing their viability, and promoting cell death.

Anti-biofilm properties of wound dressing incorporating nonrelease polycationic antimicrobials.

Polycationic nanoparticles show biocompatible, broad-spectrum bactericidal properties in vitro and in vivo when incorporated in denture lining material post-maxillectomy in head and neck cancer patients. In the present study, the synthesized Crosslinked quaternary ammonium polyethylenimine nanoparticles were found to have a strong bactericidal activity against a wide variety of microorganisms rapidly killing bacterial cells when incorporated at small concentrations into soft lining materials without compromising mechanical and biocompatibility properties. This appears advantageous over conventional released antimicrobials with regard to in vivo efficacy and safety, and may provide a convenient platform for the development of non-released antimicrobials. This is a crucial issue when it comes to giving an answer to the serious and life-threatening problems of contaminations in immunocompromised patients such as orofacial cancer patient.

Rapid kill-novel endodontic sealer and Enterococcus faecalis.

With growing concern over bacterial resistance, the identification of new antimicrobial means is paramount. In the oral cavity microorganisms are essential to the development of periradicular diseases and are the major causative factors associated with endodontic treatment failure. As quaternary ammonium compounds have the ability to kill a wide array of bacteria through electrostatic interactions with multiple anionic targets on the bacterial surface, it is likely that they can overcome bacterial resistance. Melding these ideas, we investigated the potency of a novel endodontic sealer in limiting Enterococcus faecalis growth. We used a polyethyleneimine scaffold to synthesize nano-sized particles, optimized for incorporation into an epoxy-based endodontic sealer. The novel endodontic sealer was tested for its antimicrobial efficacy and evaluated for biocompatibility and physical eligibility. Our results show that the novel sealer foundation affixes the nanoparticles, achieving surface bactericidal properties, but at the same time impeding nanoparticle penetration into eukaryotic cells and thereby mitigating a possible toxic effect. Moreover, adequate physical properties are maintained. The nanosized quaternary amine particles interact within minutes with bacteria, triggering cell death across wide pH values. Throughout this study we demonstrate a new antibacterial perspective for endodontic sealers; a novel antibacterial, effective and safe antimicrobial means.