Water-resistant antibacterial properties of a graphene oxide/cetylpyridinium chloride complex formed on medical gauze fibers.

OBJECTIVES: Graphene oxide (GO) is a nanocarbon material with a high aspect ratio (width:thickness) and abundant anionic functional groups on its surface. In this study, we attached GO to the surface of medical gauze fibers, constructed a complex with a cationic surface active agent (CSAA), and demonstrated that the treated gauze exhibits antibacterial activity even after rinsing with water. METHODS: Medical gauze was immersed in GO dispersion (0.001%, 0.01%, and 0.1%), rinsed with water, dried, and subjected to the Raman spectroscopy analysis. Subsequently, the gauze treated with 0.001% GO dispersion was immersed in 0.1% cetylpyridinium chloride (CPC) solution, immediately rinsed with water, and dried. Untreated, GO-only, and CPC-only gauzes were prepared for comparison. Each gauze was placed in a culture well, seeded with Escherichia coli or Actinomyces naeslundii, and turbidity was measured after 24 h of incubation. RESULTS: The Raman spectroscopy analysis of the gauze after immersion and rinsing showed a G band peak, indicating that GO remained on the surface of the gauze. The turbidity measurements indicated that GO/CPC-treated gauze (GO-treated and rinsed, followed by CPC-treatment and rinsing) significantly decreased turbidity compared to the other gauzes (P < 0.05), suggesting that the GO/CPC complex remained on the gauze fibers even after water rinsing and showed antibacterial activity. CONCLUSIONS: The GO/CPC complex imparts water-resistant antibacterial properties to gauze and has the potential to be widely used for the antimicrobial treatment of clothes.

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, XRB/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.

Periodontal tissue regeneration by recombinant human collagen peptide granules applied with ß-tricalcium phosphate fine particles.

OBJECTIVES: Recombinant human collagen peptide (RCP) is a recombinantly created xeno-free biomaterial enriched in arginine-glycine-aspartic acid sequences with good processability whose use for regenerative medicine applications is under investigation. The biocompatibility and osteogenic ability of RCP granules combined with ß-tricalcium phosphate (TCP) submicron particles (ß-TCP/RCP) were recently demonstrated. In the present study, ß-TCP/RCP was implanted into experimental periodontal tissue defects created in beagles to investigate its regenerative effects. METHODS: An RCP solution was lyophilized, granulated, and thermally cross-linked into particles approximately 1 mm in diameter. ß-TCP dispersion (1 wt%; 500 µL) was added to 100 mg of RCP granules to form ß-TCP/RCP. A three-walled intrabony defect (5 mm × 3 mm × 4 mm) was created on the mesial side of the mandibular first molar and filled with ß-TCP/RCP. RESULTS: A micro-computed tomography image analysis performed at 8 weeks postoperative showed a significantly greater amount of new bone after ß-TCP/RCP grafting (2.2-fold, P < 0.05) than after no grafting. Histological findings showed that the transplanted ß-TCP/RCP induced active bone-like tissue formation including tartaric acid-resistant acid phosphatase- and OCN-positive cells as well as bioabsorbability. Ankylosis did not occur, and periostin-positive periodontal ligament-like tissue formation was observed. Histological measurements performed at 8 weeks postoperative revealed that ß-TCP/RCP implantation formed 1.7-fold more bone-like tissue and 2.1-fold more periodontal ligament-like tissue than the control condition and significantly suppressed gingival recession and epithelial downgrowth (P < 0.05). CONCLUSIONS: ß-TCP/RCP implantation promoted bone-like and periodontal ligament-like tissue formation, suggesting its efficacy as a periodontal tissue regenerative material.

Sustained antibacterial coating with graphene oxide ultrathin film combined with cationic surface-active agents in a wet environment.

Antimicrobial surfactants contained in mouthrinse have excellent efficacy, but are not retained on the tooth surface (are rinsed away) due to their low water resistance and thus do not exhibit sustained antibacterial activity. We have developed a new coating method using graphene oxide (GO) that retains the surfactant on the tooth surface even after rinsing with water, thus providing a sustained antibacterial effect. Ultra-thin films of GO and an antimicrobial agent were prepared by (1) applying GO to the substrate surface, drying, and thoroughly rinsing with water to remove excess GO to form an ultrathin film (almost a monolayer, transparent) on the substrate surface, then (2) applying antimicrobial cationic surface active agents (CSAAs) on the GO film to form a composite coating film (GO/CSAA). GO/CSAA formation was verified by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and ζ-potential and contact angle measurements. GO/CSAA was effective at inhibiting the growth of oral pathogens for up to 7 days of storage in water, and antibacterial activity was recovered by reapplication of the CSAA. Antibacterial GO/CSAA films were also formed on a tooth substrate. The results suggest that GO/CSAA coatings are effective in preventing oral infections.

Ultrasonic irrigation of periodontal pocket with surface pre-reacted glass-ionomer (S-PRG) nanofiller dispersion improves periodontal parameters in beagle dogs.

OBJECTIVES: Surface pre-reacted glass-ionomer (S-PRG) nanofiller, an antibacterial ion-releasing bioactive glass, has been shown to adhere to tooth surfaces and reported to improve inflammatory parameters in experimental periodontitis. In this study, cementum substrate was irrigated ultrasonically with dispersion to examine in-vitro nanofiller adhesion and antibacterial activity. Moreover, periodontal pockets in a beagle dog were ultrasonically irrigated with dispersion to assess periodontal healing. METHODS: The morphology of human cementum irrigated with S-PRG nanofiller dispersion was examined by scanning electron microscopy and energy dispersive X-ray spectrometry. The antibacterial activity of the treated cementum was tested using Actinomyces naeslundii. In addition, experimentally formed periodontal pockets in beagle dog were ultrasonically irrigated with S-PRG nanofiller dispersion. Periodontal parameters (gingival index, bleeding on probing, probing pocket depth, and clinical attachment level) were measured from baseline (0 weeks) through 12 weeks. Moreover, the effects of irrigation with S-PRG nanofiller on changes in periodontal microflora and bone healing were analyzed. RESULTS: After ultrasonic irrigation, S-PRG nanofiller adhered to the cementum and exhibited antibacterial activity. The periodontal parameters were shown to improve following ultrasonic irrigation with S-PRG nanofiller dispersion. Analysis by next-generation sequencing revealed that the ratio of red-complex species decreased in the pockets irrigated with S-PRG nanofiller dispersion. In addition, the S-PRG nanofiller showed the potential to promote bone healing. CONCLUSIONS: Ultrasonic irrigation with S-PRG nanofiller dispersion using an ultrasonic scaler system permitted delivery of the S-PRG nanofiller to the root surface, providing improved parameters in experimental periodontitis and modifying the composition of subgingival periodontal microflora.

Periodontal tissue engineering using an apatite/collagen scaffold obtained by a plasma- and precursor-assisted biomimetic process.

BACKGROUND AND OBJECTIVES: In the treatment of severe periodontal destruction, there is a strong demand for advanced scaffolds that can regenerate periodontal tissues with adequate quality and quantity. Recently, we developed a plasma- and precursor-assisted biomimetic process by which a porous collagen scaffold (CS) could be coated with low-crystalline apatite. The apatite-coated collagen scaffold (Ap-CS) promotes cellular ingrowth within the scaffold compared to CS in rat subcutaneous tissue. In the present study, the osteogenic activity of Ap-CS was characterized by cell culture and rat skull augmentation tests. In addition, the periodontal tissue reconstruction with Ap-CS in a beagle dog was compared to that with CS. METHODS: The plasma- and precursor-assisted biomimetic process was applied to CS to obtain Ap-CS with a low-crystalline apatite coating. The effects of apatite coating on the scaffold characteristics (i.e., surface morphology, water absorption, Ca release, protein adsorption, and enzymatic degradation resistance) were assessed. Cyto-compatibility and the osteogenic properties of Ap-CS and CS were assessed in vitro using preosteoblastic MC3T3-E1 cells. In addition, we performed in vivo studies to evaluate bone augmentation and periodontal tissue reconstruction with Ap-CS and CS in a rat skull and canine furcation lesion, respectively. RESULTS: As previously reported, the plasma- and precursor-assisted biomimetic process generated a low-crystalline apatite layer with a nanoporous structure that uniformly covered the Ap-CS surface. Ap-CS showed significantly higher water absorption, Ca release, lysozyme adsorption, and collagenase resistance than CS. Cell culture experiments revealed that Ap-CS was superior to CS in promoting the osteoblastic differentiation of MC3T3-E1 cells while suppressing their proliferation. Additionally, Ap-CS significantly promoted (compared to CS) the augmentation of the rat skull bone and showed the potential to regenerate alveolar bone in a dog furcation defect. CONCLUSION: Ap-CS fabricated by the plasma- and precursor-assisted biomimetic process provided superior promotion of osteogenic differentiation and bone neoformation compared to CS.

Antibacterial coating of tooth surface with ion-releasing pre-reacted glass-ionomer (S-PRG) nanofillers.

OBJECTIVES: Surface pre-reacted glass-ionomer (S-PRG) fillers release antibacterial borate and fluoride ions. We fabricated nanoscale S-PRG fillers (S-PRG nanofillers) for antibacterial coating of tooth surfaces and assessed the antibacterial effects of this coating in vitro. In addition, we creating a canine model of periodontitis to evaluate the effectiveness of S-PRG nanofiller application on tooth roots and improvement of periodontal parameters. METHODS: Human dentin blocks were coated with S-PRG nanofiller (average particle size: 0.48 µm) and then characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDX), and ion-releasing test. Antibacterial effects of dentin blocks coated with S-PRG nanofiller were examined using bacterial strains, Streptococcus mutans and Actinomyces naeslundii. Next, we created an experimental model of periodontitis in furcation of premolars of beagle dogs. Then, S-PRG nanofiller coating was applied onto exposed tooth root surfaces. Periodontal parameters, gingival index (GI), bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment level (CAL), were measured from baseline until 4 weeks. In addition, bone healing was radiographically and histologically examined. RESULTS: SEM and EDX revealed that S-PRG nanofillers uniformly covered the dentin surface after coating. Dentin blocks coated with S-PRG nanofiller showed ion-releasing property, bacterial growth inhibition, and sterilization effects. In the experimental periodontitis model, S-PRG nanofiller coating significantly reduced clinical inflammatory parameters, such as GI (P < 0.01) and BOP (P < 0.05), compared to uncoated samples. In addition, PPD and CAL significantly decreased by S-PRG nanofiller coating (2 weeks: P < 0.05; 3 and 4 weeks: P < 0.01), suggesting the improvement of periodontitis. Micro-CT and histology revealed that bone healing of furcation defects was enhanced by S-PRG nanofiller coating. CONCLUSION: S-PRG nanofiller coating provides antibacterial effects to tooth surfaces and improves clinical parameters of periodontitis.

Bone forming ability of recombinant human collagen peptide granules applied with ß-tricalcium phosphate fine particles.

Recombinant human collagen peptide, developed based on human collagen type I, contains an arginyl-glycyl-aspartic acid (RGD)-rich motif to enhance cell behavior and is anticipated as a xeno-free polymer material for use in tissue engineering. We fabricated granules containing recombinant human collagen peptide (RCP) applied with beta-tricalcium phosphate fine particles (RCP/ß-TCP) as bone filling scaffold material and assessed the bone forming ability of RCP/ß-TCP. Recombinant peptide was thermal crosslinked and freeze-dried to prepare RCP. An aqueous dispersion of ß-TCP fine particles was added to RCP to obtain RCP/ß-TCP. Subsequently, RCP/ß-TCP were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), and cell culture assessments. Furthermore, RCP/ß-TCP were implanted into rat cranial bone defects for radiographic and histological evaluations. In SEM and EDX analyses of RCP/ß-TCP, ß-TCP particles dose-dependently covered the surface of RCP. Cell culture tests showed that RCP/ß-TCP remarkably promoted proliferation and mRNA expression of various genes, such as integrin ß1 and osteogenic markers, of osteoblastic MC3T3-E1 cells. Histomorphometric assessment at 4 weeks showed that RCP/ß-TCP significantly promoted new skull bone formation compared to RCP (p < 0.05) and control (no application) (p < 0.01). Accordingly, these findings suggest RCP/ß-TCP possess bone forming capability and would be beneficial for bone tissue engineering therapy.

In Vitro and in Vivo Analysis of Mineralized Collagen-Based Sponges Prepared by a Plasma- and Precursor-Assisted Biomimetic Process.

Three-dimensional (3D) porous scaffolds for supporting cell adhesion and growth play a vital role in tissue engineering applications. In the present study, three different collagen-based 3D sponges were functionalized by apatite coating. The sponges were coated with apatite on their outer and inner surfaces while retaining their interconnecting pores. To achieve this, we employed a vacuum degassing system in our plasma- and precursor-assisted biomimetic process using a supersaturated calcium phosphate solution. The resulting apatite-coated sponges (mineralized sponges) showed better cell adhesion properties in vitro for osteoblast-like MC3T3-E1 cells compared to that of uncoated sponges. The three mineralized sponges were implanted in the subcutaneous tissue of rats. Upon histological evaluation after 10 days, the mineralized sponges showed cell in-growth rates that were approximately 4-fold greater than those of the untreated sponges without any notable inflammatory reactions. As these sponges are composed of clinically approved collagen-based frameworks and possess a 3D porous structure with a mineralized surface appropriate for cell adhesion and internalization, further in vitro and in vivo studies should be conducted regarding tissue engineering applications.