Hydrolytic degradation characteristics of aliphatic polyesters derived from lactic and glycolic acids

Li, Suming

doi:10.1002/(sici)1097-4636(1999)48:3<342::aid-jbm20>3.0.co;2-7

Cited by 597 publications

(476 citation statements)

References 49 publications

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“…O processo é homogêneo inicialmente, gerando oligômeros solúveis em água em toda a extensão do material. Os produtos presentes na superfície da matriz são difundidos para o meio, entretanto, a baixa taxa de difusão dos produtos da reação no interior do material gera um acúmulo de ácidos, fazendo com que estruturas densas tenham uma erosão inicial na superfície, mas apresentando uma degradação mais acentuada no centro [19] .…”

Section: Suportes (Scaffolds) Suportes (Scaffolds) Suportes (Scaffoldunclassified

“…O primeiro estágio de degradação consiste na penetração e difusão das moléculas de água nas regiões amorfas do material, e subseqüente cisão hidrolítica das ligações ésteres das cadeias poliméricas. O segundo estágio se dá quando parte considerável da região amorfa esta degradada, e prossegue no centro dos domínios cristalinos [19] . Dessa forma, para polímeros parcialmente cristalinos, a literatura descreve um aumento porcentual da porção cristalina devido à absorção dos fragmentos pela rede cristalina e pela formação de novos cristais, através do rearranjo das cadeias de menor massa molar originadas no processo de degradação [33] .…”

Section: Cristalinidade Cristalinidade Cristalinidade Cristalinidade unclassified

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Polímeros bioreabsorvíveis na engenharia de tecidos

Barbanti

Zavaglia

Duek³

2005

Polímeros

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[3] , sistemas para liberação controlada de drogas [4] , stents [5] e dispositivos ortopédicos [6] . Atualmente fazem parte do cotidiano dos centros cirúrgicos no mundo inteiro.Embora muitos dispositivos protéticos artificiais estejam disponíveis, poucos podem substituir completamente todas as complexas funções biológicas. Em situações clíni-cas mais severas somente o transplante do órgão retoma as atividades orgânicas. Assim, de uma forma idealizada, a melhor alternativa seria obter um novo órgão ou tecido, substituindo aquele que não desempenha normalmente suas funções. Nos dias de hoje, a idéia da reconstrução de órgãos e tecidos criados em laboratório é amplamente difundida e investigada no mundo todo [7,8] . Resumo: A Engenharia de Tecidos consiste em um conjunto de conhecimentos e técnicas para a reconstrução de novos órgãos e tecidos. Baseada em conhecimentos das áreas de ciência e engenharia de materiais, biológica e médica, a técnica envolve a expansão in vitro de células viáveis do paciente doador sobre suportes de polímeros bioreabsorvíveis. O suporte degrada enquanto um novo órgão ou tecido é formado. Os poli(α-hidróxi ácidos) representam a principal classe de polímeros sintéticos bioreabsorvíveis e biodegradáveis utilizados na engenharia de tecidos. No desenvolvimento e na seleção desses materiais, o tempo de degradação é fundamental para o sucesso do implante. Os estudos e os desafios atuais são normalmente direcionados ao entendimento das relações entre composição química, cristalinidade, morfologia do suporte, e o processamento desses materiais. Este artigo faz uma revisão dos trabalhos recentes sobre a utilização dos polímeros sintéticos bioreabsorvíveis como suportes na engenharia de tecidos. Engenharia de tecidos Palavras-chave: Engenharia de tecidos, polímeros bioreabsorvíveis, poli(α-hidróxi ácidos). Bioresorbable Polymers in Tissue EngineeringAbstract: Tissue Engineering is based on a group of techniques for the reconstruction of new organs and tissues. Based on knowledge of materials science and engineering, biology and medicine, the technique involves the in vitro expansion of viable cells obtained from the patient on the polymeric scaffolds. The scaffold degrades while a new organ or tissue is formed. The poly(α-hydroxy acids) are the principal biodegradable and bioresorbable polymers used in tissue engineering. In developing and selecting bioresorbable scaffolds, the degradation time is fundamental for successful biocompatibility and biofuncionality. Hence, degradation studies often address variables such as the chemical composition, crystallinity, morphology of the scaffold and the processing of these materials. This paper reviews recent work in bioresorbable polymers used as scaffolds in the tissue engineering. Keywords: Tissue engineering, bioresorbable polymers, poly(α-hydroxy acids). IntroduçãoQuando a estrutura biológica de um órgão ou tecido não pode ser reparada, a alternativa viável para o restabelecimento das funções normais do paciente é repô-la com um implante feito de um b...

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Section: Suportes (Scaffolds) Suportes (Scaffolds) Suportes (Scaffoldunclassified

Section: Cristalinidade Cristalinidade Cristalinidade Cristalinidade unclassified

Polímeros bioreabsorvíveis na engenharia de tecidos

Barbanti

Zavaglia

Duek³

2005

Polímeros

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“…In this study, LLA: PC molar ratio in the copolymer was higher than 10, according to the integration ratio between signals at 5.15 ppm from methine protons of LLA and at 3.25 ppm from the -N + (CH 3 ) 3 of PC units in the 1 HNMR spectrum. Owing to the existence of more hydrophobic LLA units in PLLA-PC, film rehydration method was thus not suitable for the preparation of nanoparticles.…”

Section: The Preparation and Morphology Of Plla-pc Nanoparticlesmentioning

confidence: 99%

“…These polymers have been used for temporary therapeutic applications such as sutures, osteosynthetic devices, sustained drug delivery devices, and scaffolds in tissue engineering (e.g., Li, S et al [1,2,3]). However, they suffer from some disadvantages and thus are largely limited in further application as drug delivery materials.…”

Section: Introductionmentioning

confidence: 99%

The preparation of phosphorylcholine-containing poly(Llactide) nanoparticles with solvent evaporation method

Cao¹,

Chen²,

Chen³

et al. 2010

E-Polymers

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Phosphorylcholine-containing poly(L-lactide) (PLLA-PC) is a kind of amphiphilic copolymer synthesized with L-lactide (LLA) as monomer and glycerophosphorylcholine as ring-opening reagent. In this paper, self-assembly nanoparticles of PLLA-PC were prepared with solvent evaporation method. The factors that affected the properties and stability of nanoparticles were investigated. Transmission electron microscope (TEM) indicated that PLLA-PC nanoparticles presented typical core/shell structure. The critical micelle concentration (CMC) was determined with fluorescent probe method. The results showed that the CMCs were quite low (< 1×10 -3 g/l) and were dependent on LLA units in the copolymer. The size of the nanoparticles was detected by dynamic light scattering (DLS). The results indicated that the size could be affected by LLA units, the amount of solvent and water in the preparation process. On the other hand, the obtained nanoparticles were stable while being stored at 4 0 C, and hardly changed over the dilution with water, which was of great importance in venous injection. The solubility of clofazimine was better in aqueous solution of PLLA-PC nanoparticles than in pure water. This preliminary study suggested that PLLA-PC nanoparticles had a great potential as delivery system for hydrophobic drug.

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“…The use of synthesized polymers in the biomedical domain gained considerable attention from different researchers in the last decade [1–8]. A wide range of these polymers are available, and have further advantages to be tunable in biological, physic-chemical, mechanical and optical properties to match the requirements of specific applications.…”

Section: Introductionmentioning

confidence: 99%

Miscibility of poly(acrylic acid)/poly(methyl vinyl ketone) blend and in vitro application as drug carrier system

Alghamdi

Alsolami

Saeed

et al. 2018

Designed Monomers and Polymers

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A series of poly(acrylic acid)/poly(methyl vinyl ketone) (PAA/PMVK) blends with different compositions were prepared by the solvent casting method. The miscibility of this pair of polymers was investigated by differential scanning calorimetry(DSC), Fourier transform infra-red (FTIR) and X-Ray diffraction (XRD) techniques. An in-vitro cytotoxicity test of the drug-carrier system via MTT (3-(4,5-demethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay revealed no significant cytotoxic effects at concentrations up to 100 µg· ml−1. The STX/PAA-50 drug carrier systems were also prepared by solvent casting of solutions containing the sulfamethoxazole (STX) used as drug model and PAA/PMVK blend in N.N-dimethylformamide then crosslinked with acidified ethylene glycol. The release dynamic of STX from the prepared hydrogels was investigated in which the diffusion through the polymer matrix, the enhancement of the water solubility of STX, the influence of the initial drug concentration, the pH of the medium, and the effect of the degree of swelling of the polymer matrix on the release dynamic was evaluated. According to the total gastrointestinal transit time estimated by Belzer, the estimate distribution of STX released in the different organs indicated that the performance is obtained with the drug – carrier-system containing equal ratios of polymer and 10 wt% of STX (STX-10/PAA-50).

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Hydrolytic degradation characteristics of aliphatic polyesters derived from lactic and glycolic acids

Cited by 597 publications

References 49 publications

Polímeros bioreabsorvíveis na engenharia de tecidos

Polímeros bioreabsorvíveis na engenharia de tecidos

The preparation of phosphorylcholine-containing poly(Llactide) nanoparticles with solvent evaporation method

Miscibility of poly(acrylic acid)/poly(methyl vinyl ketone) blend and in vitro application as drug carrier system

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