Navegando por Palavras-chave "Trimetafosfato De Sódio"

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    Desenvolvimento de novos materiais dentários: efeito do peptídeo autopolimerizante P11-4 e do trimetafosfato de sódio na degradação do colágeno I e na formação de Hidroxiapatita
    (Universidade Federal de São Paulo (UNIFESP), 2020-09-24) Carvalho, Rafael Guzella De [UNIFESP]; Tersariol, Ivarne Luis Dos Santos [UNIFESP]; Universidade Federal de São Paulo
    Objectives: This study investigated the influence of peptide P11-4 (Ace-QQRFEWEFEQQ-NH2) and sodium trimetaphosphate (STMP) on the rate of calcium phosphate crystal growth, its anti-proteolytic action against the enzymatic degradation of type I collagen, the binding mechanism of P11-4 and STMP to collagen fibrils, and the potential mechanism to induce collagen stabilization. It was also evaluated the cell viability and the gene expression of different major genes involved in mineralization in odontoblast-like cells exposed to different concentrations of P11-4 and STMP. Methods: P11-4 interaction with calcium was analyzed by intrinsic fluorescence analysis. Crystalline particles formation was monitored by light-scattering detectors to estimate pH variation and radial size of the crystalline particles as a function of reaction time (pH 7.4, 25 ºC) in the presence of P11-4 or STMP in supersaturated calcium phosphate solution (Ca/P=1.67). Images were obtained under the atomic force microscopy (AFM) to measure the particle size in the presence of P11-4 or STMP and to measure the width of collagen fibrils in the presence of P11-4. The interaction of P11-4 and collagen I was analyzed by surface plasmon resonance (SPR). The binding mechanism of P11-4 and STMP to collagen fibrils were assessed with intrinsic fluorescence analysis and circular dichroism spectrometry (CD) respectively. Immortalized rat odontoblast cells (MDPC-23) were cultured. Cell viability was assessed by Trypan Blue staining and MTT assay. The changes in gene expression balance induced by P11-4 and STMP were assessed by qRT-PCR assays. Three-point bending test was used to obtain the elastic modulus of fully demineralized dentin beams before and after immersion in STMP solutions. We also performed assays of bond strength to microtensile, nanoinfiltration and in situ zymography to assess the effects of P11-4 on stabilizing the structure of dentine carie-affected. Data was statistically analyzed (α=0.05). Results: Intrinsic fluorescence analysis, dynamical light scattering with pH monitoring and AFM showed P11-4 induces hydroxyapatite (HAP) crystal nucleation process improving the structural match among HAP crystallite aggregates. STMP greatly increased the rate of crystal growth, significantly increasing the average radial crystal size. AFM corroborated the significant increase of STPM treated crystal size. SPR and AFM indicated that P11-4 binds to collagen type I fibers, increasing their width from 214 ± 4 nm to 308 ± 5 nm (P < 0.0001). The CD and intrinsic xvii fluorescence analysis showed the peptide sequence Ace-KGHRGFSGL-NH2 is the binding site of P11-4 and STMP in type I collagen. CD analysis demonstrated changes in the conformational stability after STMP binding to type I collagen. Mineralized collagen I fibrils exhibited less collagenase degradation with lower STMP concentration. P11-4 also increased the resistance of collagen type I fibers against the proteolytic activity of collagenases. We verified from the analysis of the elastic module for the treated substrate STMP and the analysis of nanoinfiltration, bond strength to microtensile and in situ zymography of the caries-affected dentin treated with P11-4 that these biomaterials stabilize the extracellular dentinal matrix. P11-4 and STMP had no significance influence in the cell viability of MDPC-23 cells and only P11-4 had significant influence in gene expression of these cells. Conclusion: The present study observed that P11-4 and STMP induces the nucleation of hydroxyapatite, interacts with collagen type I and increased resistance of collagen against the proteolytic activity of collagenases, improving the mechanical properties of the extracellular dentin matrix.