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J Mech Behav Biomed Mater ; 121: 104590, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34077907


Treatment the deeper and remineralizable carious zone (DRCZ) in dentin with various remineralizing methods, either with classic top-down or biomimetic bottom-up remineralization approaches, has remained a constant main issue to enhance dentin substrate bonding quality. The concern of remineralizing the remaining, partially demineralized and physiologically re-mineralizable collagen fibrils was the optimum target. However, applying already mineralized type I collage fibrils which have the ability to chemically cross-link with remaining collagen and minerals did not gain much interest. Synthesis of collagen/hydroxyapatite (Col/Hap) nanocomposite was done with self-assembling Hap in situ onto Col fibrils with different % (70/30, 50/50, 30/70% of Col/Hap, respectively). Micro-tensile bond strength (µTBS) was evaluated after pre-treatment of artificially demineralized dentin with these suggested protocols [nanocomposite together with grape seed extract (GSE; 6.5%) cross-linker for two periods, 10min and 1 h] then applying self-adhesive bonding system. Applied Col/Hap (30/70%) together with GSE (6.5%) gave the significantly highest µTBS (25.04 ± 5.47 and 25.53 ± 7.64 MPa, for 10min and 1 h application times, respectively). After thermocycling for 10,000 cycles at 5 and 55 °C, µTBS for all protocols and both application times substantially decreased especially for the two control groups. Using the suggested dentin pre-treatment protocols, in chair-side, may possibly enhance the bond strength to DRCZ and its durability.

Colagem Dentária , Nanocompostos , Colágeno , Dentina , Adesivos Dentinários , Durapatita , Teste de Materiais , Cimentos de Resina , Resistência à Tração
Nanotechnology ; 32(25): 255602, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33797397


We describe new method for preparing DNA nanospheres for a self-assembled atenolol@DNA (core/shell) drug delivery system. In this paper, we propose the electrochemical transformation of an alkaline polyelectrolyte solution of DNA into DNA nanospheres. We successfully electrosynthesized DNA nanospheres that were stable for at least 2 months at 4 °C. UV-visible spectra of the prepared nanospheres revealed a peak ranging from 372 to 392 nm depending on the DNA concentration and from 361 to 398.3 nm depending on the electrospherization time. This result, confirmed with size distribution curves worked out from transmission electron microscopy (TEM) images, showed that increasing electrospherization time (6, 12 and 24 h) induces an increase in the average size of DNA nanospheres (48, 65.5 and 117 nm, respectively). In addition, the average size of DNA nanospheres becomes larger (37.8, 48 and 76.5 nm) with increasing DNA concentration (0.05, 0.1 and 0.2 wt%, respectively). Also, the affinity of DNA chains for the surrounding solvent molecules changed from favorable to bad with concomitant extreme reduction in the zeta potential from -31 mV to -17 mV. Principally, the attractive and hydrophobic interactions tend to compact the DNA chain into a globule, as confirmed by Fourier transform infrared spectroscopy (FTIR) and TEM. To advance possible applications, we successfully electro self-assembled an atenolol@DNA drug delivery system. Our findings showed that electrospherization as a cost-benefit technique could be effectively employed for sustained drug release. This delivery system achieved a high entrapment efficiency of 68.03 ± 2.7% and a moderate drug-loading efficiency of 3.73%. The FTIR spectra verified the absence of any chemical interaction between the drug and the DNA during the electrospherization process. X-ray diffraction analysis indicated noteworthy lessening in atenolol crystallinity. The present findings could aid the effectiveness of electrospherized DNA for use in various other pharmaceutical and biomedical applications.

Heliyon ; 5(12): e02986, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31886428


Formation of bacterial biofilm on indwelling urinary catheters usually causes catheter-associated urinary tract infections (CAUTIs) that represent high percent of nosocomial infections worldwide. Therefore, coating urinary catheter with antibacterial and antifouling coating using facile technique is in great demand. In this study, commercial urinary catheter was coated with a layer of the self-polymerized polydopamine which acts as active platform for the in situ formation of silver nanoparticle (AgNPs) on catheter surface. The formed coating was intensively characterized using spectroscopic and microscopic techniques. The coated catheter has the potential to release silver ion in a sustained manner with a concentration of about 2-4 µg ml-1. Disk diffusion test and colony forming unites assay verified the significant bactericidal potential of the AgNPs coated catheter against both gram-positive and gram-negative bacteria as a consequence of silver ion release. In contrast to commercial catheter, the AgNPs coated catheter prevented the adherence of bacterial cells and biofilm formation on their surfaces. Interestingly, scanning electron microscope investigations showed that AgNPs coated catheter possess greater antifouling potential against gram-positive bacteria than against gram-negative bacteria. Overall, the remarkable antibacterial and antifouling potential of the coated catheter supported the use of such facile approach for coating of different medical devices for the prevention of nosocomial infections.

Carbohydr Polym ; 89(1): 236-44, 2012 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-24750629


The present study involves the development of stabilized and densely dispersed chitosan-silver nanoparticles using a green approach based on electrochemical oxidation/complexation process followed by UV irradiation reduction. Formation of the nanoparticles was confirmed by appearance of surface plasmon absorption around 420 nm. The nanoparticles were characterized using transmission electron microscopy, X-ray diffraction, elemental analysis, atomic absorption, energy dispersive X-ray, Fourier transform infrared, and UV-Visible spectrophotometry. The obtained nanoparticles were uniform and spherical with average size of 2-16 nm. It was found that increasing the Ag content in the chitosan-Ag based films tends to decrease their equilibrium swelling values. The nanoparticles also demonstrated a relatively high antibacterial activity against Bacillus thuringiensis and Pseudomonas aeruginosa bacteria as compared to that of chitosan and the antibacterial activity increased with increasing the nanoparticle concentration. The obtained results revealed that the prepared nanoparticles could be tailored and used in various biomedical applications.

Antibacterianos/química , Quitosana/química , Nanopartículas Metálicas/química , Prata/química , Antibacterianos/farmacologia , Antibacterianos/efeitos da radiação , Bacillus thuringiensis/efeitos dos fármacos , Bacillus thuringiensis/crescimento & desenvolvimento , Quitosana/efeitos da radiação , Técnicas Eletroquímicas , Nanopartículas Metálicas/efeitos da radiação , Microscopia Eletrônica de Transmissão , Oxirredução , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Prata/farmacologia , Prata/efeitos da radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Raios Ultravioleta , Difração de Raios X
Biomed Mater ; 3(3): 034121, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18765896


Nano-sized calcium deficient hydroxyapatite (CDHA) powders with an average particle size less than 100 nm were prepared by a co-precipitation method at low temperature. The initial Ca/P molar ratio was chosen to be less than the stoichiometric ratio of beta-TCP (1.5). Additionally, lowering the temperature and pH values accelerated HPO(4)(2-) incorporation in the CDHA structure. HPO(4)(2-) is considered as an essential source for beta-TCP formation. Sulfate ion doping during the maturation period is proved to be an effective step to eliminate the pyrophosphate P(2)O(7)(2-) phase that results during the calcination of CDHA with Ca/P < 1.5. Furthermore, the heating effect of microwave irradiation resulted in an increase in Ca ion concentration and lowered the CDHA deficiency which affected beta-TCP purity despite its ability to reduce the particle size. A purity of 99.32% beta-TCP with respect to the P(2)O(7)(2-) phase was achieved by increasing the sulfate ion concentration from 2% to 3% and the calcination temperatures from 900 degrees C to 1100 degrees C.

Substitutos Ósseos/química , Fosfatos de Cálcio/química , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Sulfatos/química , Implantes Absorvíveis , Absorção , Líquidos Corporais/química , Substitutos Ósseos/efeitos da radiação , Fosfatos de Cálcio/efeitos da radiação , Elasticidade/efeitos da radiação , Dureza/efeitos da radiação , Íons , Teste de Materiais , Micro-Ondas , Nanoestruturas/efeitos da radiação , Tamanho da Partícula , Doses de Radiação , Sulfatos/efeitos da radiação