Novel nanomaterial-based antibacterial photodynamic therapies to combat oral bacterial biofilms and infectious diseases

Progress and trends in photodynamic therapy research in oral science: A bibliometric analysis

BACKGROUND

Photodynamic therapy is garnering increasing attention in oral science. Despite its promising potential, further exploration is warranted to delve into the research paradigms and evolving trends within oral science. Therefore, this study aimed to conduct a comprehensive bibliometric analysis of photodynamic therapy in oral science (PDTOS), investigating research landscapes, identifying key contributors, analyzing collaborative networks, pinpointing emerging research directions, and exploring factors influencing high citations.

METHODS

Research and review articles in PDTOS were retrieved from the Web of Science Core Collection database up to December 31, 2023. The R package "bibliometrix" and VOSviewer were utilized for visualizing collaboration networks and keyword co-occurrence, alongside trend analysis. Negative binomial regression was used to model factors affecting citation counts.

RESULTS

A total of 2784 articles with significant international collaboration (23.14 %) were analyzed. Brazil, China, the USA, Iran, and Italy led in publications, with predominant USA-European collaborations. The University of Sao Paulo in Brazil was the most published institution in the field. Photodiagnosis and Photodynamic Therapy was the core journal in the field and has the highest number of publications. The main research fields included photodynamic therapy, antibacterial and anticancer treatment, management, and peri‑implant periodontitis, with a recent focus on peri‑implantitis. Factors such as international cooperation, funding, article age, type, author count, and references significantly influenced citations.

CONCLUSIONS

This research provided valuable insights into PDTOS trends and knowledge structures. These findings underscored a significant increase in the number of PDTOS publications, urging strengthened international cooperation. Emerging research has focused on peri‑implantitis and nano-photosensitizer materials. Authors should consider various citation-related factors in their research endeavors.

Effects of Hexagonal Boron Nitride and Mesoporous Silica Nanoparticles on the Morphology, Mechanical Properties and Antimicrobial Activity of Dental Composites

Hexagonal boron nitride (HBN), an artificial material with unique properties, is used in many industries. This article focuses on the extent to which hexagonal boron nitride and silica nanoparticles (MSN) affect the physicochemical and mechanical properties and antimicrobial activity of prepared dental composites. In this study, HBN, and MSN were used as additives in dental composites. 5% and 10% by weight of HBN are added to the structure of the composite materials. FTIR analysis were performed to determine the components of the produced boron nitride powders, hexagonal boron nitride-containing composites, and filling material applications. The structural and microstructural properties of dental composites have been extensively characterized using X-ray diffractometry (XRD). Surface morphology and distributions of nano boron nitride were determined by scanning electron microscopy (SEM)-EDS. In addition, the solubility of dental composites in water and their stability in water and chemical solution (Fenton) were determined by three repetitive experiments. Finally, the antimicrobial activity of dental composites was detected by using Minimum Inhibitory Concentration (MIC) measurement, as well as Minimum Fungicidal Concentration (MFC) method against yeast strain Saccharomyces cerevisiae, and Minimum Bactericidal Concentration (MBC) method against bacteria strains, Staphylococcus aureus and Escherichia coli. Since the HMP series have better antimicrobial activity than the HP series, they are more suitable for preventing dental caries and for long-term use of dental composites. In addition, when HMP and HP series added to the composite are compared, HMP-containing dental composites have better physicochemical and mechanical properties and therefore have a high potential for commercialization.

Membrane-anchoring selenophene viologens for antibacterial photodynamic therapy against periodontitis via restoring subgingival flora and alleviating inflammation

Antibacterial photodynamic therapy (aPDT) has emerged as a promising strategy for treating periodontitis. However, the weak binding of most photosensitizers to bacteria and the hypoxic environment of periodontal pockets severely hamper the therapeutic efficacy. Herein, two novel oxygen-independent photosensitizers are developed by introducing selenophene into viologens and modifying with hexane chains (HASeV) or quaternary ammonium chains (QASeV), which improve the adsorption to bacteria through anchoring to the negatively charged cell membrane. Notably, QASeV binds only to the bacterial surface of Porphyromonas gingivalis and Fusobacterium nucleatum due to electrostatic binding, but HASeV can insert into their membrane by strong hydrophobic interactions. Therefore, HASeV exhibits superior antimicrobial activity and more pronounced plaque biofilm disruption than QASeV when combined with light irradiation (MVL-210 photoreactor, 350-600 nm, 50 mW/cm2), and a better effect on reducing the diversity and restoring the structure of subgingival flora in periodontitis rat model was found through 16S rRNA gene sequencing analysis. The histological and Micro-CT analyses reveal that HASeV-based aPDT has a better therapeutic effect in reducing periodontal tissue inflammation and alveolar bone resorption. This work provides a new strategy for the development of viologen-based photosensitizers, which may be a favorable candidate for the aPDT against periodontitis.

Photodynamic impact of curcumin enhanced silver functionalized graphene nanocomposites on Candida virulence

Candida species are escalating resistance to conventional antifungal treatments, intensifying their virulence, and obstructing the effectiveness of antifungal medications. Addressing this challenge is essential for effectively managing Candida infections. The overarching objective is to advance the development of more efficient and precise therapies tailored to counter Candida infections. This study focuses on developing antifungal combined drugs using curcumin-enhanced silver-functionalized graphene nanocomposites (Cur-AgrGO) to effectively target key virulence factors of C. albicans, C. tropicalis, and C. glabrata (Candida spp.). The green reduction of graphene oxide (GO) using bioentities and active molecules makes this approach cost-effective and environmentally friendly. The nanocomposites were characterized using various techniques. Combining Cur-AgrGO with photodynamic therapy (PDT) demonstrated effective antifungal and antibiofilm activity with delayed growth and metabolism. The nanocomposites effectively suppressed hyphal transition and reduced key virulence factors, including proteinases, phospholipases, ergosterol levels, and cell membrane integrity. The findings suggest that Cur-AgrGO + PDT has potential as a treatment option for Candida infections. This innovative approach holds promise for treating Candida infections.

Evaluation of visible light and natural photosensitizers against Staphylococcus epidermidis and Staphylococcus saprophyticus planktonic cells and biofilm

Antimicrobial photoinactivation (API) has shown some promise in potentially treating different nosocomial bacterial infections, however, its application on staphylococci, especially other than Staphylococcus aureus or methicillin-resistant S. aureus (MRSA) species is still limited. Although S. aureus is a well-known and important nosocomial pathogen, several other species of the genus, particularly coagulase-negative Staphylococcus (CNS) species such as Staphylococcus epidermidis and Staphylococcus saprophyticus, can also cause healthcare-associated infections and foodborne intoxications. CNS are often involved in resilient biofilm formation on medical devices and can cause infections in patients with compromised immune systems or those undergoing invasive procedures. In this study, the effects of chlorophyllin and riboflavin-mediated API on S. epidermidis and S. saprophyticus planktonic cells and biofilm are demonstrated for the first time. Based on the residual growth determination and metabolic reduction ability changes, higher inactivating efficiency of chlorophyllin-mediated API was determined against the planktonic cells of both tested species of bacteria and against S. saprophyticus biofilm. Some insights on whether aqueous solutions of riboflavin and chlorophyllin, when illuminated with optimal exciting wavelength (440 nm and 402 nm, respectively) generate O2-•, are also provided in this work.

Antimicrobial Photodynamic Therapy Using Encapsulated Protoporphyrin IX for the Treatment of Bacterial Pathogens

Herein, we report on the antimicrobial photodynamic effect of polymeric nanoparticles containing the endogenous photosensitizer protoporphyrin IX. Compared to equivalent doses of the free photosensitizer, we demonstrated that the photodynamic antimicrobial efficacy of PLGA (polylactic-co-glycolic acid) nanoparticles containing protoporphyrin IX (PpIX) against pathogenic Staphylococcus aureus (S. aureus) is preserved after encapsulation, while photobleaching is reduced. In addition, compared to equivalent doses of the free porphyrin, we show that a reduction in the cytotoxicity in mammalian cell cultures is observed when encapsulated. Therefore, the encapsulation of protoporphyrin IX reduces its photodegradation, while the released photosensitizer maintains its ability to generate reactive oxygen species upon light irradiation. The polymeric nanoencapsulation promotes aqueous solubility for the hydrophobic PpIX, improves its photostability and reduces the cytotoxicity, while providing an extended release of this endogenous photosensitizer.

Cyclic peptide conjugated photosensitizer for targeted phototheranostics of gram-negative bacterial infection

Antimicrobial photodynamic therapy (PDT) is a promising alternative to antibiotics for eradicating pathogenic bacterial infections. It holds advantage of not inducing antimicrobial resistance but is limited for the treatment of gram-negative bacterial infection due to the lack of photosensitizer (PS) capable of targeted permeating the outer membrane (OM) of gram-negative bacteria. To facilitate the targeted permeability of PS, cyclic polymyxin b nonapeptide that can specifically bind to the lipopolysaccharide on OM, is conjugated to an FDA approved PS chlorin e6 via variable linkers. Based on structure to activity study, C6pCe6 with aminohexanoic linker and P2pCe6 with amino-3, 6-dioxaoctanoic linker are identified to preferentially image gram-negative bacteria. These two conjugates also exhibit improved aqueous dispersity and enhanced ROS generation, consequently enabled their selective bactericidal activities against gram-negative bacteria upon 660 nm light irradiation. The effective photobactericidal ability of P2pCe6 is further validated on P. aeruginosa infected G. mellonella. Moreover, it is demonstrated to effectively treat the P. aeruginosa infection and accelerate the healing process at the wound site of mouse. Owing to the light irradiation triggered targeted imaging and enhanced bactericidal capacities, P2pCe6 hold great potential to serve as a potent PS for mediating the phototheranostics of gram-negative bacterial infection.

Addressing Antimicrobial Properties in Guided Tissue/Bone Regeneration Membrane: Enhancing Effectiveness in Periodontitis Treatment

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) are the two surgical techniques generally used for periodontitis disease treatment. These techniques are based on a barrier membrane to direct the growth of new bone and gingival tissue at sites with insufficient volumes or dimensions of bone or gingiva for proper function, esthetics, or prosthetic restoration. Numerous studies have highlighted biocompatibility, space-creation, cell-blocking, bioactivity, and proper handling as essential characteristics of a membrane's performance. Given that bacterial infection is the primary cause of periodontitis, we strongly believe that addressing the antimicrobial properties of these membranes is of utmost importance. Indeed, the absence of effective inhibition of periodontal pathogens has been recognized as a primary factor contributing to the failure of GTR/GBR membranes. Therefore, we suggest considering antimicrobial properties as one of the key factors in the design of GTR/GBR membranes. Antibiotics are potent medications frequently administered systemically to combat microbes and mitigate bacterial infections. Nevertheless, the excessive use of antibiotics has resulted in a surge in bacterial resistance. To overcome this challenge, alternative antibacterial substances have been developed. In this review, we explore the utilization of alternative substances with antimicrobial properties for topical application in membranes. The use of antibacterial nanoparticles, phytochemical compounds, and antimicrobial peptides in this context was investigated. By carefully selecting and integrating antimicrobial agents into GTR/GBR membranes, we can significantly enhance their effectiveness in combating periodontitis. These antibacterial substances not only act as barriers against pathogenic bacteria but also promote the process of periodontal healing.

Regulation of the upconversion effect to promote the removal of biofilms on a titanium surface via photoelectrons

Biofilms on public devices and medical instruments are harmful. Hence, it is of great importance to fabricate antibacterial surfaces. In this work, we target the preparation of an antibacterial surface excited by near-infrared light via the coating of rare earth nanoparticles (RE NPs) on a titanium surface. The upconverted luminescence is absorbed by gold nanoparticles (Au NPs, absorber) to produce hot electrons and reactive oxygen species to eliminate the biofilms. The key parameters in tuning the upconversion effect to eliminate the biofilms are systematically investigated, which include the ratios of the sensitizer, activator, and matrix in the RE NPs, or the absorber Au NPs. The regulated RE NPs exhibit an upconversion quantum yield of 3.5%. Under illumination, photogenerated electrons flow through the surface to bacteria, such as E. coli, which disrupt the breath chain and eventually lead to the death of bacteria. The mild increase of the local temperature has an impact on the elimination of biofilms on the surface to a certain degree as well. Such a configuration on the surface of titanium exhibits a high reproducibility on the removal of biofilms and is functional after the penetration of light using soft tissue. This work thus provides a novel direction in the application of upconversion materials to be used in the fabrication of antibacterial surfaces.

Inhibition of pathogenic microbes in oral infectious diseases by natural products: Sources, mechanisms, and challenges

The maintenance of oral health is of utmost importance for an individual's holistic well-being and standard of living. Within the oral cavity, symbiotic microorganisms actively safeguard themselves against potential foreign diseases by upholding a multifaceted equilibrium. Nevertheless, the occurrence of an imbalance can give rise to a range of oral infectious ailments, such as dental caries, periodontitis, and oral candidiasis. Presently, clinical interventions encompass the physical elimination of pathogens and the administration of antibiotics to regulate bacterial and fungal infections. Given the limitations of various antimicrobial drugs frequently employed in dental practice, the rising incidence of oral inflammation, and the escalating bacterial resistance to antibiotics, it is imperative to explore alternative remedies that are dependable, efficacious, and affordable for the prevention and management of oral infectious ailments. There is an increasing interest in the creation of novel antimicrobial agents derived from natural sources, which possess attributes such as safety, cost-effectiveness, and minimal adverse effects. This review provides a comprehensive overview of the impact of natural products on the development and progression of oral infectious diseases. Specifically, these products exert their influences by mitigating dental biofilm formation, impeding the proliferation of oral pathogens, and hindering bacterial adhesion to tooth surfaces. The review also encompasses an examination of the various classes of natural products, their antimicrobial mechanisms, and their potential therapeutic applications and limitations in the context of oral infections. The insights garnered from this review can support the promising application of natural products as viable therapeutic options for managing oral infectious diseases.

Effect of antibacterial photodynamic therapy with chitosan nanoparticles on Aggregatibacter actinomycetemcomitans

BACKGROUND

This study aimed to assess the effect of antibacterial photodynamic therapy (aPDT) with chitosan nanoparticles on Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) in the culture medium.

MATERIALS AND METHODS

In this in vitro, experimental study, chitosan nanoparticles (CHNPs) containing indocyanine green (ICG) were first synthesized and characterized. A. actinomycetemcomitans was cultured on trypticase soy agar. The culture media containing A. actinomycetemcomitans were randomly subjected to the following six decontamination protocols: negative control subjected to sterile phosphate buffered saline (PBS) for 5 min, positive control exposed to 0.2 % chlorhexidine (CHX) for 5 min, exposure to 0.25 mg/mL ICG in the dark at 37 °C for 5 min, aPDT with 0.25 mg/mL ICG and diode laser (808 nm, 250 mW, 14.94 J/cm2, 30 s, 1 mm distance, 8 mm tip diameter), exposure to CHNPs containing 0.25 mg/mL ICG in the dark at 37 °C for 5 min, and aPDT with CHNPs containing 0.25 mg/mL ICG and diode laser. The number of colonies was counted, and analyzed by one-way ANOVA and Tamhane test (alpha=0.050).

RESULTS

Antimicrobial PDT with CHNPs, and CHX groups comparably showed the highest decontamination efficacy (P = 0.000).

CONCLUSION

The results showed optimal efficacy of aPDT with CHNPs containing 0.25 mg/mL ICG and 808 nm diode laser for reduction of A. actinomycetemcomitans colony count. Thus, aPDT appears to be as effective as CHX, but with fewer adverse effects.

Ferroptosis boosted oral cancer photodynamic therapy by carrier-free Sorafenib-Ce6 self-assembly nanoparticles

Oral cancer is a disease with high morbidity and mortality worldwide and greatly impacts the quality of life, especially in patients with advanced stages. Photodynamic therapy (PDT) is one of the most effective clinical treatments for oral cancers. However, most clinically applied photosensitizers have several deficiencies, including oxygen dependence, poor aqueous solubility, and a lack of tumor-targeting ability. Herein, the carrier-free multifunctional Sorafenib (Sor), chlorin e6 (Ce6), and Fe3+ self-assembly co-delivery nanoparticles (Sor-Ce6 NPs) were constructed via combining a ferroptosis inducer Sor and a photosensitizer Ce6 for synergetic therapy. The as-synthesized Sor-Ce6 NPs presented excellent colloidal stability and water dispersity with good in vivo tumor-targeting ability. More significantly, the low dose of Sor-Ce6 NPs had little dark toxicity but produced significantly enhanced ROS and supplied O2 sustainably to increase phototoxicity through ferroptosis pathway. Notably, the Sor-Ce6 NPs showed significantly higher in vitro and in vivo anti-tumor efficacy than the Sor/Ce6 mixture due to the improvement of cellular uptake and the incorporation of foreign Fe ions in the system, which also confer the T1 magnetic resonance-guided imaging ability to the formed Sor-Ce6 NPs. Our study demonstrates a promising self-assembled strategy for overcoming hypoxia-related PDT resistance for oral cancer treatment.

Advances in reparative materials for infectious bone defects and their applications in maxillofacial regions

Infectious bone defects are characterized by the partial loss or destruction of bone tissue resulting from bacterial contaminations subsequent to diseases or external injuries. Traditional bone transplantation and clinical methods are insufficient in meeting the treatment demands for such diseases. As a result, researchers have increasingly focused on the development of more sophisticated biomaterials for improved therapeutic outcomes in recent years. This review endeavors to investigate specific reparative materials utilized for the treatment of infectious bone defects, particularly those present in the maxillofacial region, with a focus on biomaterials capable of releasing therapeutic substances, functional contact biomaterials, and novel physical therapy materials. These biomaterials operate via heightened antibacterial or osteogenic properties in order to eliminate bacteria and/or stimulate bone cells regeneration in the defect, ultimately fostering the reconstitution of maxillofacial bone tissue. Based upon some successful applications of new concept materials in bone repair of other parts, we also explore their future prospects and potential uses in maxillofacial bone repair later in this review. We highlight that the exploration of advanced biomaterials holds promise in establishing a solid foundation for the development of more biocompatible, effective, and personalized treatments for reconstructing infectious maxillofacial defects.

Evaluation of antibacterial effect of a cationic porphyrin derivative on Pseudomonas aeruginosa in photodynamic therapy

BACKGROUND

Pseudomonas aeruginosa is a gram-negative bacterium without spores, and it is one of the pathogens that easily cause secondary infectious diseases when human immune function is low. The purpose of this study is to explore the inhibitory effect of photodynamic antibacterial chemotherapy-induced by cationic porphyrin derivative on clinical P. aeruginosa and its mechanism.

METHODS

The uptake of photosensitizer by P. aeruginosa and L929 cells was measured by an ultraviolet spectrophotometer. Effect of laser energy density on the bacterial activity of P. aeruginosa and post antibiotic effect were measured by bacterial suspension and tenfold dilution method. Flow cytometry and scanning electron microscopy were used to observe the activity and morphological changes of P. aeruginosa after PACT treatment.

RESULTS

The uptake of Tetra-ATPP-Lys-by P. aeruginosa and L929 was shown as concentration-dependent and time-dependent. However the uptake of L929 cell had a clear difference with P. aeruginosa at the same time and concentration intervals(P < 0.05).The increasing laser energy density had a high inactivation effect of on P. aeruginosa at the same Tetra-ATPP-Lys-concentration(P < 0.05). Post-antibiotic effect of Tetra-ATPP-Lys -PACT was dose-dependent(P < 0.05). Bacterial viability which evaluated by the flow cytometry method demonstrated that the proportion of viable bacteria is decreased with the photosensitizer dose-dependent. The morphology and microstructure of P. aeruginosa after Tetra-ATPP-Lys -PACT was demonstrated by a scanning electron microscope(SEM). After PACT, the morphology of P. aeruginosa was rod-shaped, the outer membrane surface was rough, and the bacteria were dry flat, sunken, shrunk and deformed.

CONCLUSIONS

Cationic porphyrin photosensitizer had a great damage effect on P. aeruginosa under the PACT, which can effectively destroy the microstructure of bacteria and lead to bacterial inactivation and death.

Titanium-Dioxide-Nanoparticle-Embedded Polyelectrolyte Multilayer as an Osteoconductive and Antimicrobial Surface Coating

Bioactive surface coatings have retained the attention of researchers and physicians due to their versatility and range of applications in orthopedics, particularly in infection prevention. Antibacterial metal nanoparticles (mNPs) are a promising therapeutic, with vast application opportunities on orthopedic implants. The current research aimed to construct a polyelectrolyte multilayer on a highly porous titanium implant using alternating thin film coatings of chitosan and alginate via the layer-by-layer (LbL) self-assembly technique, along with the incorporation of silver nanoparticles (AgNPs) or titanium dioxide nanoparticles (TiO2NPs), for antibacterial and osteoconductive activity. These mNPs were characterized for their physicochemical properties using quartz crystal microgravimetry with a dissipation system, nanoparticle tracking analysis, scanning electron microscopy, and atomic force microscopy. Their cytotoxicity and osteogenic differentiation capabilities were assessed using AlamarBlue and alkaline phosphatase (ALP) activity assays, respectively. The antibiofilm efficacy of the mNPs was tested against Staphylococcus aureus. The LbL polyelectrolyte coating was successfully applied to the porous titanium substrate. A dose-dependent relationship between nanoparticle concentration and ALP as well as antibacterial effects was observed. TiO2NP samples were also less cytotoxic than their AgNP counterparts, although similarly antimicrobial. Together, these data serve as a proof-of-concept for a novel coating approach for orthopedic implants with antimicrobial and osteoconductive properties.

Mechanisms underlying the effects, and clinical applications, of oral microbiota in lung cancer: current challenges and prospects

The oral cavity contains a site-specific microbiota that interacts with host cells to regulate many physiological processes in the human body. Emerging evidence has suggested that changes in the oral microbiota can increase the risk of lung cancer (LC), and the oral microbiota is also altered in patients with LC. Human and animal studies have shown that oral microecological disorders and/or specific oral bacteria may play an active role in the occurrence and development of LC through direct and/or indirect mechanisms. These studies support the potential of oral microbiota in the clinical treatment of LC. Oral microbiota may therefore be used in the prevention and treatment of LC and to improve the side effects of anticancer therapy by regulating the balance of the oral microbiome. Specific oral microbiota in LC may also be used as screening or predictive biomarkers. This review summarizes the main findings in research on oral microbiome-related LC and discusses current challenges and future research directions.

Cyclodextrin: A prospective nanocarrier for the delivery of antibacterial agents against bacteria that are resistant to antibiotics

Supramolecular chemistry introduces us to the macrocyclic host cyclodextrin, which has a hydrophobic cavity. The hydrophobic cavity has a higher affinity for hydrophobic guest molecules and forms host-guest complexation with non-covalent interaction. Three significant cyclodextrin kinds are α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin. The most often utilized is β-cyclodextrin (β-CD). An effective weapon against bacteria that are resistant to antibiotics is cyclodextrin. Several different kinds of cyclodextrin nanocarriers (β-CD, HP-β-CD, Meth-β-CD, cationic CD, sugar-grafted CD) are utilized to enhance the solubility, stability, dissolution, absorption, bioavailability, and permeability of the antibiotics. Cyclodextrin also improves the effectiveness of antibiotics, antimicrobial peptides, metallic nanoparticles, and photodynamic therapy (PDT). Again, cyclodextrin nanocarriers offer slow-release properties for sustained-release formulations where steady-state plasma antibiotic concentration is needed for an extended time. A novel strategy to combat bacterial resistance is a stimulus (pH, ROS)-responsive antibiotics released from cyclodextrin carrier. Once again, cyclodextrin traps autoinducer (AI), a crucial part of bacterial quorum sensing, and reduces virulence factors, including biofilm formation. Cyclodextrin helps to minimize MIC in particular bacterial strains, keep antibiotic concentrations above MIC in the infection site and minimize the possibility of antibiotic and biofilm resistance. Sessile bacteria trapped in biofilms are more resistant to antibiotic therapy than bacteria in a planktonic form. Cyclodextrin also involves delivering antibiotics to biofilm and resistant bacteria to combat bacterial resistance.

Recent advances in metal nanoparticles to treat periodontitis

The gradual deterioration of the supporting periodontal tissues caused by periodontitis, a chronic multifactorial inflammatory disease, is thought to be triggered by the colonization of dysbiotic plaque biofilms in a vulnerable host. One of the most prevalent dental conditions in the world, periodontitis is now the leading factor in adult tooth loss. When periodontitis does develop, it is treated by scraping the mineralized deposits and dental biofilm off the tooth surfaces. Numerous studies have shown that non-surgical treatment significantly improves clinical and microbiological indices in individuals with periodontitis. Although periodontal parameters have significantly improved, certain bacterial reservoirs often persist on root surfaces even after standard periodontal therapy. Periodontitis has been treated with local or systemic antibiotics as well as scaling and root planning. Since there aren't many brand-new antibiotics on the market, several researchers are currently concentrating on creating alternate methods of combating periodontal germs. There is a delay in a study on the subject of nanoparticle (NP) toxicity, which is especially concerned with mechanisms of action, while the area of nanomedicine develops. The most promising of them are metal NPs since they have potent antibacterial action. Metal NPs may be employed as efficient growth inhibitors in a variety of bacteria, making them useful for the treatment of periodontitis. In this way, the new metal NPs contributed significantly to the development of efficient anti-inflammatory and antibacterial platforms for the treatment of periodontitis. The current therapeutic effects of several metallic NPs on periodontitis are summarized in this study. This data might be used to develop NP-based therapeutic alternatives for the treatment of periodontal infections.

Effects of Surface Treatment Method Forming New Nano/Micro Hierarchical Structures on Attachment and Proliferation of Osteoblast-like Cells

Titanium (Ti) and Ti-based alloys are commonly used in dental implants, and surface modifications of dental implants are important for achieving osseointegration (i.e., direct connection between the implant surface and bone). This study investigated the effect of an eco-friendly etching solution-a hydrogen peroxide-sodium bicarbonate mixture-on the surface properties and contact angles of osteoblast adhesion and proliferation on Ti surfaces. Disk-shaped Ti specimens were prepared using different surface treatments (machining, sandblasting, and sandblasting/acid-etching), and they were immersed in the etching solution and ultrasonically cleaned. Surface characterization was performed using scanning electron microscopy, digital microscopy, contact angle analysis, and X-ray photoelectron spectroscopy. MG-63 osteoblasts were cultured on the specimens, and their adhesion to the specimen surface and proliferation were examined using staining and the MTT assay, respectively. Additional etching with the etching solution caused the formation of nano/micro hierarchical structures, increased surface roughness, and enhanced hydrophilicity. Osteoblast adhesion and proliferation were found to improve on the modified surfaces. The eco-friendly etching method has the potential to enhance the biological properties of Ti implant surfaces and thereby improve dental implant performance.

Effectiveness of Photodynamic Therapy as Antiseptic Measure for Oral Cavity and Pharynx: A Systematic Review

BACKGROUND

The complex traditional treatment of inflammation diseases in oral cavity includes the prescription of antibiotic and antiseptic therapy. This systematic review aims to evaluate the effect of photodynamic therapy as a part of management of inflammatory diseases in oral cavity; Methods: The study is presented in accordance with the preferred reporting points for systematic reviews and meta-analyses (PRISMA). This systematic review was conducted using electronic databases such as Medline PubMed, Scopus and the Cochrane Central Register of Controlled Trials. All the studies in this systematic review, were randomized, the risk of bias 2 (ROB 2) were assessed; Results: Considering the inclusion and exclusion criteria, we included 10 randomized clinical trials, published up to 2023 investigating the application of photodynamic therapy as a part of management of inflammatory diseases in oral cavity. The diode laser was used in the oral cavity in the zone of inflammatory process (gingivitis, mucositis, periimplantitis, marginal periodontitis, abscess, periostitis, osteomyelitis etc.) in nine studies or in the zone before surgical procedures in one study; Conclusion: Based on the results of clinical studies, it can be stated that photodynamic therapy shows good results for operations performed in the oral cavity and pharynx.

Novel Highly Efficient Antibacterial Chitosan-Based Films

In this study, we elaborated new chitosan-based films reinforced by iron(III)-containing chitosan nanoparticles Fe(III)-CS-NPs at different concentrations. We found that the optimum concentration of Fe(III)-CS-NPs for the improvement of antibacterial and mechanical properties of the films was 10% (σ_b = ca. 8.8 N/mm², ε_b = ca. 41%, inhibition zone for S. aureus = ca. 16.8 mm and for E. coli = ca. 11.2 mm). Also, using the click-chemistry approach (thiol-ene reaction), we have synthesized a novel water-soluble cationic derivative of chitin. The addition of this derivative of chitin to the chitosan polymer matrix of the elaborated film significantly improved its mechanical (σ_b = ca. 11.6 N/mm², ε_b = ca. 75%) and antimicrobial (inhibition zone for S. aureus = ca. 19.6 mm and for E. coli = ca. 14.2 mm) properties. The key mechanism of the antibacterial action of the obtained films is the disruption of the membranes of bacterial cells. The elaborated antibacterial films are of interest for potential biomedical and food applications.

Combinations of Photodynamic Therapy with Other Minimally Invasive Therapeutic Technologies against Cancer and Microbial Infections

The rapid rise in research and development following the discovery of photodynamic therapy to establish novel photosensitizers and overcome the limitations of the technology soon after its clinical translation has given rise to a few significant milestones. These include several novel generations of photosensitizers, the widening of the scope of applications, leveraging of the offerings of nanotechnology for greater efficacy, selectivity for the disease over host tissue and cells, the advent of combination therapies with other similarly minimally invasive therapeutic technologies, the use of stimulus-responsive delivery and disease targeting, and greater penetration depth of the activation energy. Brought together, all these milestones have contributed to the significant enhancement of what is still arguably a novel technology. Yet the major applications of photodynamic therapy still remain firmly located in neoplasms, from where most of the new innovations appear to launch to other areas, such as microbial, fungal, viral, acne, wet age-related macular degeneration, atherosclerosis, psoriasis, environmental sanitization, pest control, and dermatology. Three main value propositions of combinations of photodynamic therapy include the synergistic and additive enhancement of efficacy, the relatively low emergence of resistance and its rapid development as a targeted and high-precision therapy. Combinations with established methods such as chemotherapy and radiotherapy and demonstrated applications in mop-up surgery promise to enhance these top three clinical tools. From published in vitro and preclinical studies, clinical trials and applications, and postclinical case studies, seven combinations with photodynamic therapy have become prominent research interests because they are potentially easily applied, showing enhanced efficacy, and are rapidly translating to the clinic. These include combinations with chemotherapy, photothermal therapy, magnetic hyperthermia, cold plasma therapy, sonodynamic therapy, immunotherapy, and radiotherapy. Photochemical internalization is a critical mechanism for some combinations.

Synergistic Photodynamic/Antibiotic Therapy with Photosensitive MOF-Based Nanoparticles to Eradicate Bacterial Biofilms

Bacterial biofilms pose a serious threat to human health, as they prevent the penetration of antimicrobial agents. Developing nanocarriers that can simultaneously permeate biofilms and deliver antibacterial agents is an attractive means of treating bacterial biofilm infections. Herein, photosensitive metal-organic framework (MOF) nanoparticles were developed to promote the penetration of antibiotics into biofilms, thereby achieving the goal of eradicating bacterial biofilms through synergistic photodynamic and antibiotic therapy. First, a ligand containing benzoselenadiazole was synthesized and incorporated into MOF skeletons to construct benzoselenadiazole-doped MOFs (Se-MOFs). The growth of the Se-MOFs could be regulated to obtain nanoparticles (Se-NPs) in the presence of benzoic acid. The singlet oxygen (¹O₂) generation efficiencies of the Se-MOFs and Se-NPs were evaluated. The results show that the Se-NPs exhibited a higher ¹O₂ generation efficacy than the Se-MOF under visible-light irradiation because the small size of the Se-NPs was conducive to the diffusion of ¹O₂. Afterward, an antibiotic drug, polymyxin B (PMB), was conjugated onto the surface of the Se-NPs via amidation to yield PMB-modified Se-NPs (PMB-Se-NPs). PMB-Se-NPs exhibit a synergistic antibacterial effect by specifically targeting the lipopolysaccharides present in the outer membranes of Gram-negative bacteria through surface-modified PMB. Benefiting from the synergistic therapeutic effects of antibiotic and photodynamic therapy, PMB-Se-NPs can efficiently eradicate bacterial biofilms at relatively low antibiotic doses and light intensities, providing a promising nanocomposite for combating biofilm infections.

Green Ultrasound-Assisted Synthesis of Surface-Decorated Nanoparticles of Fe3O4 with Au and Ag: Study of the Antifungal and Antibacterial Activity

This work proposes a sonochemical biosynthesis of magnetoplasmonic nanostructures of Fe₃O₄ decorated with Au and Ag. The magnetoplasmonic systems, such as Fe₃O₄ and Fe₃O₄-Ag, were characterized structurally and magnetically. The structural characterizations reveal the magnetite structures as the primary phase. Noble metals, such as Au and Ag, are present in the sample, resulting in a structure-decorated type. The magnetic measurements indicate the superparamagnetic behavior of the Fe₃O₄-Ag and Fe₃O₄-Au nanostructures. The characterizations were carried out by X-ray diffraction and scanning electron microscopy. Complementarily, antibacterial and antifungal assays were carried out to evaluate the potential properties and future applications in biomedicine.

Versatile gold-silver-PB nanojujubes for multi-modal detection and photo-responsive elimination against bacteria

Bacterial infections have become a serious threat to global public health. Nanomaterials have shown promise in the development of bacterial biosensing and antibiotic-free antibacterial modalities, but single-component materials are often less functional and difficult to achieve dual bacterial detection and killing. Herein, we report a novel strategy based on the effective integration of multi-modal bacterial detection and elimination, by constructing the versatile gold-silver-Prussian blue nanojujubes (GSP NJs) via a facile template etching method. Such incorporation of multi-components involves the utilization of cores of gold nanobipyramids with strong surface-enhanced Raman scattering (SERS) activity, the shells of Prussian blue as both an efficient bio-silent SERS label and an active peroxidase-mimic, and functionalization of polyvinyl pyrrolidone and vancomycin, respectively endowing them with good colloidal dispersibility and specificity against S. aureus. The GSP NJs show operational convenience in the SERS detection and excellent peroxidase-like activity for the sensitive colorimetric detection. Meanwhile, they exhibit robust near-infrared photothermal/photodynamic effects, and the photo-promoted Ag⁺ ions release, ultimately achieving a high antibacterial efficiency over 99.9% in 5 min. The NJs can also effectively eliminate complex biofilms. The work provides new insights into the design of multifunctional core-shell nanostructures for the integrated bacterial detection and therapy.

Perspectives on Usage of Functional Nanomaterials in Antimicrobial Therapy for Antibiotic-Resistant Bacterial Infections

The clinical applications of nanotechnology are emerging as widely popular, particularly as a potential treatment approach for infectious diseases. Diseases associated with multiple drug-resistant organisms (MDROs) are a global concern of morbidity and mortality. The prevalence of infections caused by antibiotic-resistant bacterial strains has increased the urgency associated with researching and developing novel bactericidal medicines or unorthodox methods capable of combating antimicrobial resistance. Nanomaterial-based treatments are promising for treating severe bacterial infections because they bypass antibiotic resistance mechanisms. Nanomaterial-based approaches, especially those that do not rely on small-molecule antimicrobials, display potential since they can bypass drug-resistant bacteria systems. Nanoparticles (NPs) are small enough to pass through the cell membranes of pathogenic bacteria and interfere with essential molecular pathways. They can also target biofilms and eliminate infections that have proven difficult to treat. In this review, we described the antibacterial mechanisms of NPs against bacteria and the parameters involved in targeting established antibiotic resistance and biofilms. Finally, yet importantly, we talked about NPs and the various ways they can be utilized, including as delivery methods, intrinsic antimicrobials, or a mixture.

Antimicrobial Effect of the Amniotic Membrane Isolated and Associated with Photodynamic Therapy

Microbial control through alternative therapies, such as the amniotic membrane (AM) and antimicrobial photodynamic therapy (aPDT), has been gaining prominence with the advancement of bacterial resistance to conventional treatments. This study aimed to evaluate the antimicrobial effect of AM isolated and associated with aPDT using the PHTALOX® as a photosensitizer (PS) against Staphylococcus aureus and Pseudomonas aeruginosa biofilms. The groups studied were: C+; L; AM; AM+L; AM+PHTX; and AM+aPDT. The irradiation parameters were 660 nm, 50 J.cm−2, and 30 mW.cm−2. Two independent microbiological experiments were carried out in triplicate, and the results were analyzed by CFU/mL counting and a metabolic activity test, both statistically analyzed (p < 0.05). The integrity of the AM was verified after the treatments by a scanning electron microscope (SEM). The groups AM, AM+PHTX, and, mainly, AM+aPDT showed a statistical difference when compared to C+ regarding the decrease in CFU/mL and metabolic activity. SEM analysis showed significant morphological alterations in the AM+PHTX and AM+aPDT groups. The treatments with AM isolated or associated with PHTALOX® were adequate. The association had potentiated the biofilm effect, and the morphological differences presented by AM after treatment did not hinder its antimicrobial effect, encouraging its use in biofilm formation locals.

Nanomaterials-Based Wound Dressing for Advanced Management of Infected Wound

The effective prevention and treatment of bacterial infections is imperative to wound repair and the improvement of patient outcomes. In recent years, nanomaterials have been extensively applied in infection control and wound healing due to their special physiochemical and biological properties. Incorporating antibacterial nanomaterials into wound dressing has been associated with improved biosafety and enhanced treatment outcomes compared to naked nanomaterials. In this review, we discuss progress in the application of nanomaterial-based wound dressings for advanced management of infected wounds. Focus is given to antibacterial therapy as well as the all-in-one detection and treatment of bacterial infections. Notably, we highlight progress in the use of nanoparticles with intrinsic antibacterial performances, such as metals and metal oxide nanoparticles that are capable of killing bacteria and reducing the drug-resistance of bacteria through multiple antimicrobial mechanisms. In addition, we discuss nanomaterials that have been proven to be ideal drug carriers for the delivery and release of antimicrobials either in passive or in stimuli-responsive manners. Focus is given to nanomaterials with the ability to kill bacteria based on the photo-triggered heat (photothermal therapy) or ROS (photodynamic therapy), due to their unparalleled advantages in infection control. Moreover, we highlight examples of intelligent nanomaterial-based wound dressings that can detect bacterial infections in-situ while providing timely antibacterial therapy for enhanced management of infected wounds. Finally, we highlight challenges associated with the current nanomaterial-based wound dressings and provide further perspectives for future improvement of wound healing.

Rose bengal-decorated rice husk-derived silica nanoparticles enhanced singlet oxygen generation for antimicrobial photodynamic inactivation

Rice husks are well known for their high silica content, and the RH-derived silica nanoparticles (RH NPs) are amorphous and biocompatible; therefore, they are suitable raw materials for biomedical applications. In this study, rose bengal-impregnated rice husk nanoparticles (RB-RH NPs) were prepared for their potential photosensitization and ¹O₂ generation as antimicrobial photodynamic inactivation. RB is a halogen-xanthene type's photosensitizer showing high singlet oxygen efficiency, and the superior photophysical properties are desirable for RB in the antimicrobial photodynamic inactivation of bacteria. To enhance the binding of anionic RB to RH NPs, we conducted cationization for the RH NPs using polyethyleneimine (PEI). The control of the RB adsorption state on cationic PEI-modified RH NPs was essential for RB RH-NP photosensitizers to obtain efficient ¹O₂ generation. Minimizing RB aggregation allowed highly efficient ¹O₂ production from RB-RH NPs at the molar ratio of RB with the PEI, X_RB/PEI. = 0.1. The RB-RH NPs have significant antimicrobial activity against Streptococcus mutans compared to free RB after white light irradiation. The RB-RH NP-based antimicrobial photodynamic inactivation can be employed effectively in treating Streptococcus mutans for dental applications.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10853-023-08194-z.

Emerging nanosonosensitizers augment sonodynamic-mediated antimicrobial therapies

With the widespread prevalence of drug-resistant pathogens, traditional antibiotics have limited effectiveness and do not yield the desired outcomes. Recently, alternative antibacterial therapies based on ultrasound (US) have been explored to overcome the crisis of bacterial pathogens. Antimicrobial sonodynamic therapy (aSDT) offers an excellent solution that relies on US irradiation to produce reactive oxygen species (ROS) and achieve antibiotic-free mediated antimicrobial effects. In addition, aSDT possesses the advantage of superior tissue penetrability of US compared to light irradiation, demonstrating great feasibility in treating deep infections. Although existing conventional sonosensitizers can produce ROS for antimicrobial activity, some limitations, such as low penetration rate, nonspecific distribution and poor ROS production under hypoxic conditions, result in suboptimal sterilization in aSDT. Recently, emerging nanosonosensitizers have enormous advantages as high-performance agents in aSDT, which overcome the deficiencies of conventional sonosensitizers as described above. Thus, nanosonosensitizer-mediated aSDT has a bright future for the management of bacterial infections. This review classifies the current available nanosonosensitizers and provides an overview of the mechanisms, biomedical applications, recent advances and perspectives of aSDT.

Antibacterial nanophotosensitizers in photodynamic therapy: An update

Bacterial infections constitute a major challenge of clinical medicine, particularly in specialties such as dermatology and dental medicine. Antiseptics and antibiotics are the main adjunctive therapies to anti-infective procedures in these specialties. However, antibacterial photodynamic therapy (PDT) has been introduced as a novel and promising alternative to conventional antibacterial approaches. PDT relies on the formation of reactive oxygen species (ROS) by a photosensitizer (PS) after activation by a specific light source. Nanotechnology was later introduced to enhance the antibacterial efficacy of PS during PDT. In this review, we describe the different nanoparticles (NPs) used in PDT and their properties. Recent in vivo data of NPs in antibacterial PDT in dermatology and dental medicine and their safety concerns are also reviewed.

Near-Infrared-Enhanced Dual Enzyme-Mimicking Ag-TiO2-x@Alginate Microspheres with Antibactericidal and Oxygeneration Abilities to Treat Periodontitis

The effective treatment for periodontitis is to completely and sustainedly eradicate the bacterial pathogens from the complex periodontal pockets. Local sustained-release antibiotics as a complementary treatment after scaling and root planning can sustainedly combat bacterial pathogens in the periodontal pockets to help treat the disease, but the increasing concern of bacterial resistance limits its future use. Here, we reported a local antibacterial system based on microsized multifunctional Ag-TiO_2-x encapsulated in alginate (ATA) microspheres. We confirmed that ATA displayed strong photothermally enhanced dual enzyme-mimicking (peroxidase-like and catalase-like) activities and weak photocatalytic activity under 808 nm near-infrared (NIR) irradiation, which could boost the generation of reactive oxygen species (ROS) and O₂ in the presence of low-level H₂O₂. As a result, the ATA/H₂O₂/NIR system exhibited efficient antibacterial activity against Porphyromonas gingivalis and Streptococcus gordonii in both planktonic and biofilm forms. With the help of ROS, ATA could release Ag⁺ in concentrations sufficient to inhibit periodontal pathogens as well. Moreover, the in situ-generated oxygen was supposed to alleviate the local hypoxic environment and would help downregulate the lipopolysaccharide-mediated inflammatory response of periodontal stem cells. The in vivo rat periodontitis treatment results demonstrated that the ATA/H₂O₂/NIR system reduced the bacterial load, relieved inflammation, and improved tissue healing. Our work developed a new local prolonged bactericidal and oxygenation system for enhanced periodontitis. Avoiding the usage of antibiotics and nanomaterials, this strategy showed great promise in adjunctive periodontitis treatment and also in other biomedical applications.

Clinical applications of antimicrobial photodynamic therapy in dentistry

Given the emergence of resistant bacterial strains and novel microorganisms that globally threaten human life, moving toward new treatment modalities for microbial infections has become a priority more than ever. Antimicrobial photodynamic therapy (aPDT) has been introduced as a promising and non-invasive local and adjuvant treatment in several oral infectious diseases. Its efficacy for elimination of bacterial, fungal, and viral infections and key pathogens such as Streptococcus mutans, Porphyromonas gingivalis, Candida albicans, and Enterococcus faecalis have been investigated by many invitro and clinical studies. Researchers have also investigated methods of increasing the efficacy of such treatment modalities by amazing developments in the production of natural, nano based, and targeted photosensitizers. As clinical studies have an important role in paving the way towards evidence-based applications in oral infection treatment by this method, the current review aimed to provide an overall view of potential clinical applications in this field and summarize the data of available randomized controlled clinical studies conducted on the applications of aPDT in dentistry and investigate its future horizons in the dental practice. Four databases including PubMed (Medline), Web of Science, Scopus and Embase were searched up to September 2022 to retrieve related clinical studies. There are several clinical studies reporting aPDT as an effective adjunctive treatment modality capable of reducing pathogenic bacterial loads in periodontal and peri-implant, and persistent endodontic infections. Clinical evidence also reveals a therapeutic potential for aPDT in prevention and reduction of cariogenic organisms and treatment of infections with fungal or viral origins, however, the number of randomized clinical studies in these groups are much less. Altogether, various photosensitizers have been used and it is still not possible to recommend specific irradiation parameters due to heterogenicity among studies. Reaching effective clinical protocols and parameters of this treatment is difficult and requires further high quality randomized controlled trials focusing on specific PS and irradiation parameters that have shown to have clinical efficacy and are able to reduce pathogenic bacterial loads with sufficient follow-up periods.

Efficient antibacterial AIEgens induced ROS for selective photodynamic treatment of bacterial keratitis

Bacterial keratitis (BK) is an acute infection of the cornea, accompanied by uneven epithelium boundaries with stromal ulceration, potentially resulting in vision loss. Topical antibiotic is the regular treatment for BK. However, the incidence rate of multidrug-resistant bacteria limits the application of traditional antibiotics. Therefore, a cationic aggregation-induced emission luminogens (AIEgens) named TTVP is utilized for the treatment of BK. TTVP showed no obvious cytotoxicity in maintaining the normal cell morphology and viability under a limited concentration, and revealed the ability to selectively combine with bacteria in normal ocular environment. After light irradiation, TTVP produced reactive oxygen species (ROS), thus exerting efficient antibacterial ability in vitro. What's more, in rat models of Staphylococcus aureus (S. aureus) infection, the therapeutic intervention of TTVP lessens the degree of corneal opacity and inflammatory infiltration, limiting the spread of inflammation. Besides, TTVP manifested superior antibacterial efficacy than levofloxacin in acute BK, endowing its better vision salvage ability than conventional method. This research demonstrates the efficacy and advantages of TTVP as a photodynamic drug in the treatment of BK and represents its promise in clinical application of ocular infections.

Methylene Blue/Carbon Dots Composite with Photothermal and Photodynamic Properties: Synthesis, Characterization, and Antibacterial Application

Photodynamic therapy and photothermal therapy provide new ways to combat antibiotic resistance. In this research, methylene blue (MB) as an effective photosensitizer was conjugated with carbon quantum dots (CQDs), the composite product not only possessed good antibacterial properties against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) due to excellent singlet oxygen (¹ O₂ ) production rate and light heat transfer performance, but also showed good biocompatibility. Combined with 808 nm and 660 nm laser irradiation, the minimum bactericidal concentration of CQDs-MB towards S. aureus and E. coli was 5 μm. Therefore, this study provides a potential candidate material based on CQDs for clinical applications.

Silicon nanoparticles: A promising approach for control of Pseudomonas aeruginosa biofilms

Objectives

The current study aimed to investigate the control and treatment of biofilm-producing isolates of Pseudomonas aeruginosa using silicon nanoparticles (SiNPs).

Materials and Methods

Biofilm-producing isolates of P. aeruginosa were recovered from various food samples and identified through fluorescent green colony formation on selective and differential media, as well as the amplification of oprI and oprL genes. Tube methods, Congo-red agar method, and scanning electron microscopy (SEM) were used to study biofilm phenotypes. The effect of SiNPs was evaluated by broth dilution assay.

Results

The biofilm assay revealed that these isolates formed biofilms on glass surfaces within 72 hr of incubation. Scanning electron micrographs showed that the biofilm communities were composed of multicellular clusters of P. aeruginosa encased in matrix material. However, these isolates were unable to form biofilms on SiNPs-coated surfaces. The results showed that the planktonic isolates of P. aeruginosa were comparatively sensitive to the antibacterial properties of SiNPs, with minimum inhibitory concentration (MIC) ranging from 100 to 200 µg/ml. Contrarily, the biofilms were found to be 500 times more tolerant to the highest concentration of SiNPs (MIC of 500 µg/ml) and were more resistant. Under static conditions, the sedimentation of SiNPs resulted in their ineffectiveness. However, under shaking conditions, the biofilms were effectively dispersed and the cells were lysed. The results showed that SiNPs were effective against both the planktonic and the metabolically inactive forms of P. aeruginosa.

Conclusion

This study suggests that SiNPs could be a useful tool for preventing the formation of biofilms and removing pre-existing biofilms.

Characterization of a Novel Amphiphilic Cationic Chlorin Photosensitizer for Photodynamic Applications

A novel amphiphilic cationic chlorin e₆ derivative was investigated as a promising photosensitizer for photodynamic therapy. Two cationic -N(CH₃)₃⁺ groups on the periphery of the macrocycle provide additional hydrophilization of the molecule and ensure its electrostatic binding to the mitochondrial membranes and bacterial cell walls. The presence of a hydrophobic phytol residue in the same molecule results in its increased affinity towards the phospholipid membranes while decreasing its stability towards aggregation in aqueous media. In organic media, this chlorin e₆ derivative is characterized by a singlet oxygen quantum yield of 55%. Solubilization studies in different polymer- and surfactant-based supramolecular systems revealed the effective stabilization of this compound in a photoactive monomolecular form in micellar nonionic surfactant solutions, including Tween-80 and Cremophor EL. A novel cationic chlorin e₆ derivative also demonstrates effective binding towards serum albumin, which enhances its bioavailability and promotes effective accumulation within the target tissues. Laser confocal scanning microscopy demonstrates the rapid intracellular accumulation and distribution of this compound throughout the cells. Together with low dark toxicity and a rather good photostability, this compound demonstrates significant phototoxicity against HeLa cells causing cellular damage most likely through reactive oxygen species generation. These results demonstrate a high potential of this derivative for application in photodynamic therapy.

Nanomaterials-mediated photodynamic therapy and its applications in treating oral diseases

Oral diseases, such as dental caries, periodontitis and oral cancer, have a very high morbidity over the world. Basically, many oral diseases are commonly related to bacterial infections or cell malignant proliferation, and usually located on the superficial positions. These features allow the convenient and efficient application of photodynamic therapy (PDT) for oral diseases, since PDT is ideally suitable for the diseases on superficial sites and has been widely used for antimicrobial and anticancer therapy. Photosensitizers (PSs) are an essential element in PDT, which induce the generation of a large number of reactive oxygen species (ROS) upon absorption of specific lights. Almost all the PSs are small molecules and commonly suffered from various problems in the PDT environment, such as low solubility and poor stability. Recently, reports on the nanomedicine-based PDT have been well documented. Various functionalized nanomaterials can serve either as the PSs carriers or the direct PSs, thus enhancing the PDT efficacy. Herein, we aim to provide a comprehensive understanding of the features of different oral diseases and discuss the potential applications of nanomedicine-based PDT in the treatment of some common oral diseases. Also, the concerns and possible solutions for nanomaterials-mediated PDT are discussed.

State-of-the-Art on the Sulfate Radical-Advanced Oxidation Coupled with Nanomaterials: Biological and Environmental Applications

Sulfate radicals (SO₄^-·) play important biological roles in biomedical and environmental engineering, such as antimicrobial, antitumor, and disinfection. Compared with other common free radicals, it has the advantages of a longer half-life and higher oxidation potential, which could bring unexpected effects. These properties have prompted researchers to make great contributions to biology and environmental engineering by exploiting their properties. Peroxymonosulfate (PMS) and peroxydisulfate (PDS) are the main raw materials for SO₄^-· formation. Due to the remarkable progress in nanotechnology, a large number of nanomaterials have been explored that can efficiently activate PMS/PDS, which have been used to generate SO₄^-· for biological applications. Based on the superior properties and application potential of SO₄^-·, it is of great significance to review its chemical mechanism, biological effect, and application field. Therefore, in this review, we summarize the latest design of nanomaterials that can effectually activate PMS/PDS to create SO₄^-·, including metal-based nanomaterials, metal-free nanomaterials, and nanocomposites. Furthermore, we discuss the underlying mechanism of the activation of PMS/PDS using these nanomaterials and the application of SO₄^-· in the fields of environmental remediation and biomedicine, liberating the application potential of SO₄^-·. Finally, this review provides the existing problems and prospects of nanomaterials being used to generate SO₄^-· in the future, providing new ideas and possibilities for the development of biomedicine and environmental remediation.

Application of Reactive Oxygen Species in Dental Treatment

Reactive oxygen species (ROS) and free radicals, which have been implicated in inflammation, pain, carcinogenesis, and aging, are actually used in dental treatments such as tooth bleaching and composite resin polymerization. Recently, numerous studies have investigated the application of ROS in the medical and dental fields. In previous studies, ROS were generated intentionally through pathways such as photolysis, photocatalytic methods, and photodynamic therapy, which are used in the medical field to target cancer. In the field of dentistry, generated ROS are applied mainly for periodontal treatment and sterilization of the root canal, and its effectiveness as an antibacterial photodynamic therapy has been widely reported.. Given this background, the present article aimed to review the basic effects of ROS in dental medicine, especially endodontic therapy, and to discuss future applications of ROS.

The photosensitizer-based therapies enhance the repairing of skin wounds

Wound repair remains a clinical challenge and bacterial infection is a common complication that may significantly delay healing. Therefore, proper and effective wound management is essential. The photosensitizer-based therapies mainly stimulate the photosensitizer to generate reactive oxygen species through appropriate excitation source irradiation, thereby killing pathogenic microorganisms. Moreover, they initiate local immune responses by inducing the recruitment of immune cells as well as the production of proinflammatory cytokines. In addition, these therapies can stimulate the proliferation, migration and differentiation of skin resident cells, and improve the deposition of extracellular matrix; subsequently, they promote the re-epithelialization, angiogenesis, and tissue remodeling. Studies in multiple animal models and human skin wounds have proved that the superior sterilization property and biological effects of photosensitizer-based therapies during different stages of wound repair. In this review, we summarize the recent advances in photosensitizer-based therapies for enhancing tissue regeneration, and suggest more effective therapeutics for patients with skin wounds.

Treatment methods toward improving the anti-infection ability of poly(etheretherketone) implants for medical applications

Due to its favorable chemical stability, biocompatibility, and mechanical properties, Poly(etheretherketone) (PEEK) is a promising material for repairing bone and dental hard tissue defects. However, there are critical disadvantages: PEEK is biologically and chemically inert, which influences osseointegration of implants and bonding strength of prostheses, and its mechanical properties still cannot meet the requirements for some medical applications. Furthermore, bacterial infections and inflammatory reactions often accompany bone defects caused by trauma or inflammation or teeth loss caused by periodontitis. Previous studies mainly focused on enhancing PEEK's bioactivity and mechanical performance, but PEEK also lacks effective anti-infection ability. Thus, it is necessary to improve its anti-infection ability, and this is considered in this paper from two aspects. The first is to inhibit the attachment and growth of bacteria on the material, and the second is to endow the material with immunoregulatory ability, which means mobilizing the host immune system to protect tissue from inflammation. In this review, we analyze and discuss the existing treatment methods to improve the antibacterial and immunomodulatory abilities of PEEK addressing their limitations, relevant future challenges, and required research efforts.

Socioeconomic Inequalities and Toothbrushing Frequency among Schoolchildren Aged 6 to 12 Years in a Multi-Site Study of Mexican Cities: A Cross-Sectional Study

Periodic toothbrushing is the most common, effective, and reliable way to mechanically remove biofilm from oral tissues. The objective of the present study was to determine the association between toothbrushing frequency and socioeconomic position for schoolchildren between 6 and 12 years of age in four cities in Mexico. A cross-sectional study was conducted on 500 Mexican schoolchildren between 6 and 12 years of age from public schools in four Mexican cities. Questionnaires were administered to the parents/guardians of the schoolchildren to obtain the variables included in the study. The dependent variable was toothbrushing frequency, dichotomized as: 0 = less than twice a day and 1 = at least twice a day. The analysis was performed in Stata. The average age of the schoolchildren was 8.9 ± 1.9 years; 50.4% were female. The prevalence of toothbrushing was 52.8% (at least twice a day) (95% CI = 48.4−57.1). In the multivariate model, the variables associated (p < 0.05) with toothbrushing frequency were older age of the schoolchild (OR = 1.14); younger age of the mother (OR = 0.93); being a girl (OR = 1.70); being enrolled in Seguro Popular (OR = 0.69); being in a household that was owned (OR = 2.43); and being a schoolchild who lived in a home that owned a car (OR = 1.31). The prevalence of toothbrushing at least twice a day was just over 50% in these Mexican children. We found demographic and socioeconomic variables to be associated with toothbrushing. Based on socioeconomic variables that were associated with toothbrushing frequency—such as health insurance, home ownership and the household owning a car—the results of the present study confirm the existence of health inequalities in toothbrushing frequency.

Antimicrobial photodynamic therapy in endodontic reintervention: A systematic review and meta-analysis

BACKGROUND

To evaluate the effectiveness of the use of antimicrobial photodynamic therapy (aPDT) in root canals disinfection in cases of endodontic retreatments.

METHODS

This Systematic Review was registered in PROSPERO (CRD42021260013) and followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Searches were performed in the electronic databases PubMeb, Scopus, Web of Science, Embase, Web of Science, Clinical Trials and Cochrane Library. Methodological quality and risk of bias were assessed by the Cochrane Risk of Bias tool for randomized clinical trials (RCT) and by the Newcastle-Ottawa (NOS) qualifier for non-RCT (prospective) studies. Meta-analysis was performed using R software, version 3.6.3 with the "META" package assistant by the RStudio platform. The odds ratio (OR) measure of effect was calculated and the random effect model was applied with a 95% confidence interval, and heterogeneity tested by the I2 index. The certainty of evidence was rated using GRADE.

RESULTS

Regarding the 1513 studies screened, 10 met the eligibility criteria and were included, and 8 used in the quantitative synthesis. Meta-analysis showed that all of studies data presented a significant difference before and after of antimicrobial photodynamic therapy in the microbial load reduction in secondary endondontic infections (OR 0.15 [0.07; 0.32], p < 0.0001). Overall, the studies had a low risk of bias and, the analysis of evidence by GRADE assessment was rated as moderate.

CONCLUSION

It is suggested that aPDT is a beneficial and promising tool, showing efficacy in reducing the microbial load in cases of endodontic retreatment.

The Potential Application of Natural Photosensitizers Used in Antimicrobial Photodynamic Therapy against Oral Infections

Oral health problems and the emergence of antimicrobial resistance among pathogenic bacterial strains have become major global challenges and are essential elements that negatively affect general well-being. Antimicrobial photodynamic therapy (APDT) is based on a light source and oxygen that activates a nontoxic photosensitizer, resulting in microbial destruction. Synthetic and natural products can be used to help the APDT against oral microorganisms. The undesirable consequences of conventional photosensitizers, including toxicity, and cost encourage researchers to explore new promising photosensitizers based on natural compounds such as curcumin, chlorella, chlorophyllin, phycocyanin, 5-aminolevulinic acid, and riboflavin. In this review, we summarize in vitro studies describing the potential use of APDT therapy conjugated with some natural products against selected microorganisms that are considered to be responsible for oral infections.