Evaluation of the anti-biofilm effect of poloxamer-based thermoreversible gel of silver nanoparticles as a potential medication for root canal therapy

In Situ Gelling Behavior and Biopharmaceutical Characterization of Nano-Silver-Loaded Poloxamer Matrices Designed for Nasal Drug Delivery

A combination of Poloxamer 407 (P407) and hydroxypropyl methylcellulose (HPMC) hydrosols is proposed as an in situ thermo-gelling vehicle for the nasal drug delivery of chlorhexidine-silver nanoparticles conjugates (SN-CX). Optimization of the formulation was carried out by applying varying ratios of P407 and HPMC in the presence and absence of SN-CX so that gelation would occur in the temperature range of the nasal cavity (30-34 °C). Mechanisms for the observed gelation phenomena were suggested based on viscosimetry, texture analysis, and dynamic light scattering. Tests were carried out for sprayability, washout time, in vitro drug release, ex vivo permeation, and antimicrobial activity. When applied separately, HPMC was found to lower the P407 gelation temperature (Tg), whereas SN-CX increased it. However, in the presence of HPMC, SN-CX interfered with the P407 micellar organization in a principally contrasting way while leading to an even further decrease in Tg. SN-CX-loaded nasal formulations composed of P407 16% and HPMC 0.1% demonstrated a desired gelation at 31.9 °C, good sprayability (52.95% coverage of the anterior nasal cavity), mucoadhesion for 70 min under simulated nasal clearance, expedient release and permeation, and preserved anti-infective activity against seasonal Influenza virus and beta-coronavirus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and other pathogens. Our findings suggest that the current development could be considered a potential formulation of a protective nasal spray against respiratory infections.

Nanoarchitectonics-Based Materials as a Promising Strategy in the Treatment of Endodontic Infections

Endodontic infections arise from the interactive activities of microbial communities colonizing in the intricate root canal system. The present study aims to update the latest knowledge of nanomaterials, their antimicrobial mechanisms, and their applications in endodontics. A detailed literature review of the current knowledge of nanomaterials used in endodontic applications was performed using the PubMed database. Antimicrobial nanomaterials with a small size, large specific surface area, and high chemical activity are introduced to act as irrigants, photosensitizer delivery systems, and medicaments, or to modify sealers. The application of nanomaterials in the endodontic field could enhance antimicrobial efficiency, increase dentin tubule penetration, and improve treatment outcomes. This study supports the potential of nanomaterials as a promising strategy in treating endodontic infections.

Application of Nanomaterials in Endodontics

Recent advancements in nanotechnology have introduced a myriad of potential applications in dentistry, with nanomaterials playing an increasing role in endodontics. These nanomaterials exhibit distinctive mechanical and chemical properties, rendering them suitable for various dental applications in endodontics, including obturating materials, sealers, retro-filling agents, and root-repair materials. Certain nanomaterials demonstrate versatile functionalities in endodontics, such as antimicrobial properties that bolster the eradication of bacteria within root canals during endodontic procedures. Moreover, they offer promise in drug delivery, facilitating targeted and controlled release of therapeutic agents to enhance tissue regeneration and repair, which can be used for endodontic tissue repair or regeneration. This review outlines the diverse applications of nanomaterials in endodontics, encompassing endodontic medicaments, irrigants, obturating materials, sealers, retro-filling agents, root-repair materials, as well as pulpal repair and regeneration. The integration of nanomaterials into endodontics stands poised to revolutionize treatment methodologies, presenting substantial potential advancements in the field. Our review aims to provide guidance for the effective translation of nanotechnologies into endodontic practice, serving as an invaluable resource for researchers, clinicians, and professionals in the fields of materials science and dentistry.

A novel small-molecule compound S-342-3 effectively inhibits the biofilm formation of Staphylococcus aureus

IMPORTANCE

Biofilms are an important virulence factor in Staphylococcus aureus and are characterized by a structured microbial community consisting of bacterial cells and a secreted extracellular polymeric matrix. Inhibition of biofilm formation is an effective measure to control S. aureus infection. Here, we have synthesized a small molecule compound S-342-3, which exhibits potent inhibition of biofilm formation in both MRSA and MSSA. Further investigations revealed that S-342-3 exerts inhibitory effects on biofilm formation by reducing the production of polysaccharide intercellular adhesin and preventing bacterial adhesion. Our study has confirmed that the inhibitory effect of S-342-3 on biofilm is achieved by downregulating the expression of genes responsible for biofilm formation. In addition, S-342-3 is non-toxic to Galleria mellonella larvae and A549 cells. Consequently, this study demonstrates the efficacy of a biologically safe compound S-342-3 in inhibiting biofilm formation in S. aureus, thereby providing a promising antibiofilm agent for further research.

Matrix-Mediated Delivery of Silver Nanoparticles for Prevention of Staphylococcus aureus and Pseudomonas aeruginosa Biofilm Formation in Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a chronic health condition affecting the sinonasal cavity. CRS-associated mucosal inflammation leads to sinonasal epithelial cell death and epithelial cell barrier disruption, which may result in recurrent bacterial infections and biofilm formation. For patients who fail medical management and elect endoscopic sinus surgery for disease control, bacterial biofilm formation is particularly detrimental, as it reduces the efficacy of surgical intervention. Effective treatments that prevent biofilm formation in post-operative patients in CRS are currently limited. To address this unmet need, we report the controlled release of silver nanoparticles (AgNps) with silk-elastinlike protein-based polymers (SELPs) to prevent bacterial biofilm formation in CRS. This polymeric network is liquid at room temperature and forms a hydrogel at body temperature, and is hence, capable of conforming to the sinonasal cavity upon administration. SELP hydrogels demonstrated sustained AgNp and silver ion release for the studied period of three days, potent in vitro antibacterial activity against Pseudomonas aeruginosa (**** p < 0.0001) and Staphylococcus aureus (**** p < 0.0001), two of the most commonly virulent bacterial strains observed in patients with post-operative CRS, and high cytocompatibility with human nasal epithelial cells. Antibacterial controlled release platform shows promise for treating patients suffering from prolonged sinonasal cavity infections due to biofilms.

Silver Nanoparticles and Their Therapeutic Applications in Endodontics: A Narrative Review

The efficient elimination of microorganisms and their byproducts from infected root canals is compromised by the limitations in conventional root canal disinfection strategies and antimicrobials. Silver nanoparticles (AgNPs) are advantageous for root canal disinfection, mainly due to their wide-spectrum anti-microbial activity. Compared to other commonly used nanoparticulate antibacterials, AgNPs have acceptable antibacterial properties and relatively low cytotoxicity. Owing to their nano-scale, AgNPs penetrate deeper into the complexities of the root canal systems and dentinal tubules, as well as enhancing the antibacterial properties of endodontic irrigants and sealers. AgNPs gradually increase the dentin hardness in endodontically treated teeth and promote antibacterial properties when used as a carrier for intracanal medication. The unique properties of AgNPs make them an ideal additive for different endodontic biomaterials. However, the possible side effects of AgNPs, such as cytotoxicity and tooth discoloration potential, merits further research.

Smart delivery systems for microbial biofilm therapy: Dissecting design, drug release and toxicological features

Bacterial biofilms are highly protected surface attached communities of bacteria that typically cause chronic infections. To address their recalcitrance to antibiotics and minimise side effects of current therapies, smart drug carriers are being explored as promising platforms for antimicrobials. Herein, we briefly summarize recent efforts and considerations that have been applied in the design of these smart carriers. We guide readers on a journey on how they can leverage the inherent biofilm microenvironment, external stimuli, or combine both types of stimuli in a predictable manner. The specific carrier features that are responsible for their 'on-demand' properties are detailed and their impact on antibiofilm property are further discussed. Moreover, an analysis on the impact of such features on drug release profiles is provided. Since nanotechnology represents a significant slice of the drug delivery pie, some insights on the potential toxicity are also depicted. We hope that this review inspires researchers to use their knowledge and creativity to design responsive systems that can eradicate biofilm infections.

Effect of Enhanced Recovery after Surgery (ERAS) Concept and Cluster Nursing on Psychological State and Pain of Oral Outpatients Undergoing Root Canal Therapy

Objective

The effect of the concept of enhanced recovery after surgery (ERAS) and pain of patients undergoing root canal therapy in oral clinic.

Methods

200 participants in an oral clinic from March 2020 to March 2022 were enrolled in our study. The control group (n = 100) accepted ERAS-based care and the research group (n = 100) accepted ERAS concept and cluster nursing. Nursing satisfaction, comfort, self-efficacy, subjective well-being, self-rating anxiety scale (SAS), and self-rating depression scale (SDS) scores were compared.

Results

The research group had 100% satisfaction rate; the control group had 87% satisfaction rate. After nursing, the scores of comforts and self-efficacy of the two groups increased and the scores of comforts and self-efficacy of the research group were higher than those of the control group. After nursing, the scores of subjective well-being of the two groups increased. Furthermore, the higher scores of life satisfaction, interpersonal harmony, and self-efficacy in the research group were found. There was no significant difference in the scores of SAS and SDS between the two groups before nursing (P > 0.05), but after nursing, the scores of SAS and SDS in the two groups decreased, and the scores of SAS and SDS in the research group were lower than those in the control group, and there are statistically significant differences between the groups (P < 0.05). The scores of visual analogue score (VAS) and numerical rating scale (NRS) following intervention decreased, and there are statistically significant differences between the groups (P < 0.05). The less physiological, psychological, social functions, and health self-cognition in the research group were displayed, and there are statistically significant differences between groups (P < 0.05).

Conclusion

The adoption of the concept of ERAS and cluster nursing can effectively improve the psychological state and pain score of oral outpatients undergoing root canal therapy, improve comfort and self-efficacy, and enhance subjective well-being and quality of life. ERAS and cluster nursing is of great significance in relieving pain after root canal therapy in the outpatient department, reducing patients' pain and improving patients' quality of life.

Potential of Bouea macrophylla kernel extract as an intracanal medicament against mixed-species bacterial-fungal biofilm. An in vitro and ex vivo study

OBJECTIVE

To investigate the antimicrobial activity of B. macrophylla kernel extract against mixed-species biofilms of E. faecalis, S. gordonii and C. albicans in vitro. To evaluate the efficacy of the extract as an intracanal medicament compared with Ca(OH)₂ and chlorhexidine in ex vivo tooth model.

METHODS

The antibiofilm effect of B. macrophylla kernel extract was determined by AlamarBlue™ assay and the effect on biofilms was visualized by LIVE/DEAD® BacLight™ viability test. Mixed-species biofilms were incubated into the tooth model (N = 42) for 21 days. The teeth were randomly divided into 4 medicament groups for 7 days: (i) normal saline, (ii) calcium hydroxide (Ca(OH)₂), (iii) chlorhexidine gel, (iv) B. macrophylla kernel extract. Dentine samples were collected, qPCR with PMA was used to quantify the viability and species composition of each sample. SEM was used to visualize the effect of medicament on biofilm structure.

RESULTS

The MBIC was 6.25 mg/mL and the MBEC was 50 mg/mL. The integrity of microbial cells was progressively compromised as concentration increased, resulting in greater cell death. Ex vivo tooth model revealed that biofilm treated with 50 mg/mL of the B. macrophylla extract demonstrated a significantly higher proportions of dead cells than in Ca(OH)₂, chlorhexidine and normal saline groups (p < 0.01). Disruption of biofilm structure and enlargement of dentinal tubules was observed in B. macrophylla group on SEM.

CONCLUSION

The extract of B. macrophylla kernel exhibited significant antibiofilm effect against the mixed-species biofilms of E. faecalis, S. gordonii and C. albicans.

Compare the physicochemical and biological properties of engineered polymer-functionalized silver nanoparticles against Porphyromonas gingivalis

Background

Some polymer-functionalized AgNPs (P-AgNPs) have been developed to optimize the biological properties of AgNPs. However, there are no studies in the literature comparing the differences in physicochemical and biological properties of AgNPs caused by various polymer-functionalizations and providing evidence for the selection of polymers to optimize AgNPs.

Methods

Two AgNPs with similar nano-size and opposite surface charges were synthesized and functionalized by seven polymers. Their physicochemical properties were evaluated by UV-Visible absorption, dynamic light scattering, transmission electron microscopy and inductively coupled plasma optical emission spectroscopy. Their biological properties against Porphyromonas gingivalis and human gingival fibroblast were investigated by MIC determination, time-dependent antibacterial assay, antibiofilm activity and cell viability assay. Silver diamine fluoride, AgNO3 and metronidazole were used as positive controls.

Results

Comparative analysis found that there were no significant differences between P-AgNPs and AgNPs in nano-size and in surface charge. Raman spectroscopy analysis provided evidence about the attachment of polymers on AgNPs. For antibacterial property, among the negatively charged AgNPs, only polyvinylpyrrolidone (PVP)-functionalized AgNPs-1 showed a significant lower MIC value than AgNPs-1 (0.79 vs. 4.72 μg/ml). Among the positively charged AgNPs, the MIC values of all P-AgNPs (0.34–4.37 μg/ml) were lower than that of AgNPs-2 (13.89 μg/ml), especially PVP- and Pluronic127-AgNPs-2 (1.75 and 0.34 μg/ml). For antibiofilm property, PVP-AgNPs-1 (7.86 μg/ml, P = 0.002) and all P-AgNPs-2 (3.42–31.14 μg/ml, P &lt; 0.001) showed great antibiofilm effect against P. gingivalis biofilm at 5* to 10*MIC level. For cytotoxicity, all negatively charged AgNPs and PVP-AgNPs-2 showed no cytotoxicity at MIC level, but significant cytotoxicity was detected at 2.5* to 10*MIC levels.

Conclusion

Among the polymers studied, polymer functionalization does not significantly alter the physical properties of AgNPs, but modifies their surface chemical property. These modifications, especially the functionalization of PVP, contribute to optimize the antibacterial and antibiofilm properties of AgNPs, while not causing cytotoxicity at the MIC level.

Antifungal activity of alexidine dihydrochloride in a novel diabetic mouse model of dermatophytosis

Dermatophytosis is one of the most prevalent fungal infections and a major public health problem worldwide. Recent years have seen a change in the epidemiological patterns of infecting fungi, corresponding to an alarming rise in the prevalence of drug-recalcitrant dermatophyte infections. In patients with diabetes mellitus, dermatophytosis is more severe and recurrent. The potency of promising new antifungal drugs in the pipeline must be expanded to include dermatophytosis. To facilitate this effort, we established a clinically pertinent mouse model of dermatophyte infections, in which diabetic mice were infected with Trichophyton mentagrophytes on abraded skin. The diabetic mouse model was optimized as a simple and robust system for simulating dermatophytoses in diabetic patients. The outcome of infection was measured using clinical and mycological parameters. Infected mice with fungal lesions were treated with oral and topical formulations of terbinafine or topical administration of the FDA-approved and repurposed pan-antifungal drug alexidine dihydrochloride (AXD). In this model, AXD was found to be highly effective, with outcomes comparable to those of the standard of care drug terbinafine.

Niclosamide-loaded nanoparticles disrupt Candida biofilms and protect mice from mucosal candidiasis

Candida albicans biofilms are a complex multilayer community of cells that are resistant to almost all classes of antifungal drugs. The bottommost layers of biofilms experience nutrient limitation where C. albicans cells are required to respire. We previously reported that a protein Ndu1 is essential for Candida mitochondrial respiration; loss of NDU1 causes inability of C. albicans to grow on alternative carbon sources and triggers early biofilm detachment. Here, we screened a repurposed library of FDA-approved small molecule inhibitors to identify those that prevent NDU1-associated functions. We identified an antihelminthic drug, Niclosamide (NCL), which not only prevented growth on acetate, C. albicans hyphenation and early biofilm growth, but also completely disengaged fully grown biofilms of drug-resistant C. albicans and Candida auris from their growth surface. To overcome the suboptimal solubility and permeability of NCL that is well known to affect its in vivo efficacy, we developed NCL-encapsulated Eudragit EPO (an FDA-approved polymer) nanoparticles (NCL-EPO-NPs) with high niclosamide loading, which also provided long-term stability. The developed NCL-EPO-NPs completely penetrated mature biofilms and attained anti-biofilm activity at low microgram concentrations. NCL-EPO-NPs induced ROS activity in C. albicans and drastically reduced oxygen consumption rate in the fungus, similar to that seen in an NDU1 mutant. NCL-EPO-NPs also significantly abrogated mucocutaneous candidiasis by fluconazole-resistant strains of C. albicans, in mice models of oropharyngeal and vulvovaginal candidiasis. To our knowledge, this is the first study that targets biofilm detachment as a target to get rid of drug-resistant Candida biofilms and uses NPs of an FDA-approved nontoxic drug to improve biofilm penetrability and microbial killing.

Poloxamer-Based Scaffolds for Tissue Engineering Applications: A Review

Poloxamer is a triblock copolymer with amphiphilicity and reversible thermal responsiveness and has wide application prospects in biomedical applications owing to its multifunctional properties. Poloxamer hydrogels play a crucial role in the field of tissue engineering and have been regarded as injectable scaffolds for loading cells or growth factors (GFs) in the last few years. Hydrogel micelles can maintain the integrity and stability of cells and GFs and form an appropriate vascular network at the application site, thus creating an appropriate microenvironment for cell growth, nerve growth, or bone integration. The injectability and low toxicity of poloxamer hydrogels make them a noninvasive method. In addition, they can also be good candidates for bio-inks, the raw material for three-dimensional (3D) printing. However, the potential of poloxamer hydrogels has not been fully explored owing to the complex biological challenges. In this review, the latest progress and cutting-edge research of poloxamer-based scaffolds in different fields of application such as the bone, vascular, cartilage, skin, nervous system, and organs in tissue engineering and 3D printing are reviewed, and the important roles of poloxamers in tissue engineering scaffolds are discussed in depth.

Combinatorial Therapeutic Strategy of Biogenics Derived from Lactobacillus fermentum PUM and Zingerone Against Pseudomonas aeruginosa PAO1-Induced Surgical Site Infection: an Experimental Study

Pseudomonas aeruginosa, a WHO-prioritized multidrug-resistant Gram-negative bacteria, is one of the frequently implicated pathogen in surgical site infection (SSI) due to its virulence phenotypes and biofilm-forming ability. In the present study, cell-free supernatant (CFS) and biogenics (organic acids and precipitated protein fraction) of indigenous potential probiotic, Lactobacillus fermentum PUM both alone and in combination with zingerone were found to inhibit pyocyanin, pyochelin, protease, elastase, the virulence factors, and motility of P. aeruginosa PAO1. Furthermore, scanning electron microscopy indicated that biofilm formation was attenuated maximally by CFS of L. fermentum combined with zingerone. In vivo study revealed reduced P. aeruginosa burden, suppuration at surgical site vis-a-vis reduced levels of oxidants, pro-inflammatory cytokines, ameliorated anti-oxidants, and healed infected surgical site compared with counter controls. In totality, combination of L. fermentum PUM-derived biogenics and zingerone could be employed to treat P. aeruginosa-induced SSI that needs to be correlated clinically.

Semiconducting Polymer Nanoparticles with Intramolecular Motion-Induced Photothermy for Tumor Phototheranostics and Tooth Root Canal Therapy

Much effort is devoted to develop agents with superior photoacoustic/photothermal properties for improved disease diagnosis and treatment. Herein, a new fused two isoindigo (DIID)-based semiconducting conjugated polymer (named PBDT-DIID) is rationally designed and synthesized with a strong near-infrared absorption band ranging from 700 to 1000 nm. Water-dispersing nanoparticles (NPs) of PBDT-DIID are prepared with good biocompatibility and a rather high photothermal conversion efficiency (70.6%), as the active excited-state intramolecular twist around the central double bonds in DIID permits most of the absorbed excitation energy flow to heat deactivation pathway through internal conversion. The photoacoustic signal can be further magnified by incorporation of polylactide (PLA) in the NP core to confine the generated heat of PBDT-DIID within NPs. The resultant doped NPs show excellent performance in photoacoustic imaging-guided photothermal therapy in an orthotopic 4T1 breast tumor-bearing mouse model. It is also found that the photothermal effect of the PBDT-DIID NPs is safe and quite efficacious to highly improve the root canal treatment outcome by heating the 1% NaClO solution inside the root canal upon 808 nm laser irradiation in a human extracted tooth root canal infection model.

Nanostructures as Targeted Therapeutics for Combating Oral Bacterial Diseases

Pathogenic oral biofilms are now recognized as a key virulence factor in many microorganisms that cause the heavy burden of oral infectious diseases. Recently, new investigations in the nanotechnology field have propelled the development of novel biomaterials and approaches to control bacterial biofilms, either independently or in combination with other substances such as drugs, bioactive molecules, and photosensitizers used in antimicrobial photodynamic therapy (aPDT) to target different cells. Moreover, nanoparticles (NPs) showed some interesting capacity to reverse microbial dysbiosis, which is a major problem in oral biofilm formation. This review provides a perspective on oral bacterial biofilms targeted with NP-mediated treatment approaches. The first section aims to investigate the effect of NPs targeting oral bacterial biofilms. The second part of this review focuses on the application of NPs in aPDT and drug delivery systems.