Browsing by Subject "Halloysite"

Now showing 1 - 4 of 4
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    Chlorhexidine-modified nanotubes and their effects on the polymerization and bonding performance of a dental adhesive
    (Elsevier, 2020-05) Kalagi, Sara; Feitosa, Sabrina A.; Münchow, Eliseu A.; Martins, Victor M.; Karczewski, Ashley E.; Cook, N. Blaine; Diefenderfer, Kim; Eckert, George J.; Geraldeli, Saulo; Bottino, Marco C.; Cariology, Operative Dentistry and Dental Public Health, School of Dentistry
    Objectives: The purpose of this study was to synthesize chlorhexidine (CHX)-encapsulated aluminosilicate clay nanotubes (Halloysite®, HNTs) and to incorporate them into the primer/adhesive components of an etch-and-rinse adhesive system (SBMP; Scotchbond Multipurpose, 3M ESPE) and to test their effects on degree of conversion, viscosity, immediate and long-term bonding to dentin. Methods: CHX-modified HNTs were synthesized using 10% or 20% CHX solutions. The primer and the adhesive components of SBMP were incorporated with 15wt.% of the CHX-encapsulated HNTs. Degree of conversion (DC) and viscosity analyses were performed to characterize the modified primers/adhesives. For bond strength testing, acid-etched dentin was treated with one of the following: SBMP (control); 0.2%CHX solution before SBMP; CHX-modified primers+SBMP adhesive; SBMP primer+CHX-modified adhesives; and SBMP primer+CHX-free HNT-modified adhesive. The microtensile bond strength test was performed after immediate (24h) and long-term (6 months) of water storage. Data were analyzed using ANOVA and Tukey (α=5%) and the Weibull analysis. Results: DC was greater for the CHX-free HNT-modified adhesive, whereas the other experimental adhesives showed similar DC as compared with the control. Primers were less viscous than the adhesives, without significant differences within the respective materials. At 24h, all groups showed similar bonding performance and structural reliability; whereas at the 6-month period, groups treated with the 0.2%CHX solution prior bonding or with the CHX-modified primers resulted in greater bond strength than the control and superior reliability. Significance: The modification of a primer or adhesive with CHX-encapsulated HNTs was an advantageous approach that did not impair the polymerization, viscosity and bonding performance of the materials, showing a promising long-term effect on resin-dentin bonds.
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    Doxycycline-loaded nanotube-modified adhesives inhibit MMP in a dose-dependent fashion
    (Springer Nature, 2018-04) Palasuk, Jadesada; Windsor, L. Jack; Platt, Jeffrey A.; Lvov, Yuri; Geraldeli, Saulo; Bottino, Marco C.; Biomedical Sciences and Comprehensive Care, School of Dentistry
    OBJECTIVES: This article evaluated the drug loading, release kinetics, and matrix metalloproteinase (MMP) inhibition of doxycycline (DOX) released from DOX-loaded nanotube-modified adhesives. DOX was chosen as the model drug, since it is the only MMP inhibitor approved by the U.S. Food and Drug Administration. MATERIALS AND METHODS: Drug loading into the nanotubes was accomplished using DOX solution at distinct concentrations. Increased concentrations of DOX significantly improved the amount of loaded DOX. The modified adhesives were fabricated by incorporating DOX-loaded nanotubes into the adhesive resin of a commercial product. The degree of conversion (DC), Knoop microhardness, DOX release kinetics, antimicrobial, cytocompatibility, and anti-MMP activity of the modified adhesives were investigated. RESULTS: Incorporation of DOX-loaded nanotubes did not compromise DC, Knoop microhardness, or cell compatibility. Higher concentrations of DOX led to an increase in DOX release in a concentration-dependent manner from the modified adhesives. DOX released from the modified adhesives did not inhibit the growth of caries-related bacteria, but more importantly, it did inhibit MMP-1 activity. CONCLUSIONS: The loading of DOX into the nanotube-modified adhesives did not compromise the physicochemical properties of the adhesives and the released levels of DOX were able to inhibit MMP activity without cytotoxicity. CLINICAL SIGNIFICANCE: Doxycycline released from the nanotube-modified adhesives inhibited MMP activity in a concentration-dependent fashion. Therefore, the proposed nanotube-modified adhesive may hold clinical potential as a strategy to preserve resin/dentin bond stability.
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    Physicochemical and Biological Properties of Novel Chlorhexidine-Loaded Nanotube-Modified Dentin Adhesive
    (Wiley, 2018-09-10) Feitosa, Sabrina A.; Palasuk, Jadesada; Geraldeli, Saulo; Windsor, L. Jack; Bottino, Marco C.; Biomedical Sciences and Comprehensive Care, School of Dentistry
    A commercially available three-step (etch-and-rinse) adhesive was modified by adding chlorhexidine (CHX)-loaded nanotubes (Halloysite®, HNT) at two concentrations (CHX10% and CHX20%). The experimental groups were: SBMP (unmodified adhesive, control), HNT (SBMP modified with HNT), CHX10 (SBMP modified with HNT loaded with CHX10%), and CHX20 (SBMP modified with HNT loaded with CHX20%). Changes in the degree of conversion (DC%), Knoop hardness (KHN), water sorption (WS), solubility (SL), antimicrobial activity, cytotoxicity, and anti-matrix metalloproteinase [MMP-1] activity (collagenase-I) were evaluated. In regards to DC%, two-way ANOVA followed by Tukey’s post-hoc test revealed that only the factor “adhesive” was statistically significant (p<0.05). No significant differences were detected in DC% when 20 s light-curing was used (p>0.05). For Knoop microhardness, one-way ANOVA followed by the Tukey’s test showed statistically significant differences when comparing HNT (20.82±1.65) and CHX20% (21.71±2.83) with the SBMP and CHX10% groups. All adhesives presented similar WS and cytocompatibility. The CHX-loaded nanotube-modified adhesive released enough CHX to inhibit the growth of S. mutans and L. casei. Adhesive eluates were not able to effectively inhibit MMP-1 activity. The evaluation of higher CHX concentrations might be necessary to provide an effective and predictable MMP inhibition.
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    Therapeutic Applications of Halloysite
    (MDPI, 2022) Mobaraki, Mohammadmahdi; Karnik, Sonali; Li, Yue; Mills, David K.; Orthopaedic Surgery, School of Medicine
    In recent years, nanomaterials have attracted significant research interest for applications in biomedicine. Many kinds of engineered nanomaterials, such as lipid nanoparticles, polymeric nanoparticles, porous nanomaterials, silica, and clay nanoparticles, have been investigated for use in drug delivery systems, regenerative medicine, and scaffolds for tissue engineering. Some of the most attractive nanoparticles for biomedical applications are nanoclays. According to their mineralogical composition, approximately 30 different nanoclays exist, and the more commonly used clays are bentonite, halloysite, kaolinite, laponite, and montmorillonite. For millennia, clay minerals have been extensively investigated for use in antidiarrhea solutions, anti-inflammatory agents, blood purification, reducing infections, and healing of stomach ulcers. This widespread use is due to their high porosity, surface properties, large surface area, excellent biocompatibility, the potential for sustained drug release, thermal and chemical stability. We begin this review by discussing the major nanoclay types and their application in biomedicine, focusing on current research areas for halloysite in biomedicine. Finally, recent trends and future directions in HNT research for biomedical application are explored.