In Vitro Biodegradability of Poly(lactic Acid)/Hydroxyapatite Biocomposites Prepared by Solvent-Blending Technique

2012 ◽  
Vol 626 ◽  
pp. 631-635 ◽  
Author(s):  
Mujtahid Kaavessina ◽  
Fitriani Khanifatun ◽  
Imtiaz Ali ◽  
Saeed M. Alzahrani
Keyword(s):  
Lactic Acid ◽  
Hydrolytic Degradation ◽  
Phosphate Buffer Solution ◽  
Weight Fraction ◽  
Poly Lactic Acid ◽  
Buffer Solution ◽  
Before And After ◽  
Micro Holes ◽  
Thermal Stability Of

Poly (lactic acid) was solvent-blended and formed as thin ribbons with different weight fraction of hydroxyapatite, namely 5, 10 and 20wt%. In-vitro biodegradability of biocomposites was performed in phosphate buffer solution (PBS) at 37°C. The presence of hydroxyapatite tended to increase biodegradability of poly (lactic acid) in its biocomposites. Thermal stability of biocomposites was always higher than that neat poly (lactic acid) either before and after hydrolytic degradation tests. After biodegradation tests, some micro-holes and cracks were appeared in the surface morphology of biocomposites as well as the increasing crystallinity occurred.

Controlled Release Characteristics of PLA-Pluronic-PLA Nano-Sized Vesicles In Vitro

2013 ◽  
Vol 785-786 ◽  
pp. 493-497
Author(s):  
Yu Ping Li ◽  
Li Zhen Sun ◽  
Xiang Yuan Xiong ◽  
Zi Ling Li ◽  
Ting Kang Xing ◽  
...  
Keyword(s):  
Controlled Release ◽  
Protein Delivery ◽  
Phosphate Buffer Solution ◽  
Entrapment Efficiency ◽  
Poly Lactic Acid ◽  
Oral Insulin ◽  
Buffer Solution ◽  
The Mean ◽  
The Stability

In the present study, controlled release characteristics of new nanosized PLA-Pluronic-PLA block copolymer vesicles comprising of amphiphilic poly (lactic acid) (PLA) and Pluronic block copolymers (PEO-PPO-PEO) have been evaluated as an oral insulin carrier. The mean size of vesicles was 78 nm for PLA-F127-PLA and 165 nm for PLA-P85-PLA copolymer. The mean insulin entrapment efficiency was 59.6% for PLA-P85-PLA and 26.4% for PLA-F127-PLA. The in vitro release characteristics of insulin from vesicles exhibited an initial burst in the range of pH 1.2-7.4 dissolution mediums. The presence of PLA-Pluronic-PLA vesicles improved the stability of insulin in the gastrointestinal fluids than that of the phosphate buffer solution (PBS) of insulin. More importantly, the released insulin from the vesicles maintained their biological activity. The results from this studies demonstrated that biodegradable PLA-Pluronic-PLA can self-assemble with insulin, form insulin-encapsulated vesicles, and is good carrier materials for oral insulin/protein delivery.

Thermal stability of poly(lactic acid) before and after γ-radiolysis

1999 ◽  
Vol 48 (10) ◽  
pp. 980-984 ◽  
Author(s):  
A Babanalbandi ◽  
D J T Hill ◽  
D S Hunter ◽  
L Kettle
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Poly Lactic Acid ◽  
Before And After ◽  
Thermal Stability Of

scholarly journals Biological Compatibility of a Polylactic Acid Composite Reinforced with Natural Chitosan Obtained from Shrimp Waste

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1465 ◽  
Author(s):  
Yaret Torres-Hernández ◽  
Gloria Ortega-Díaz ◽  
Lucía Téllez-Jurado ◽  
Nayeli Castrejón-Jiménez ◽  
Alejandro Altamirano-Torres ◽  
...  
Keyword(s):  
Cell Viability ◽  
Polylactic Acid ◽  
Low Cost ◽  
Hydrolytic Degradation ◽  
Phosphate Buffer Solution ◽  
Morphological Characteristics ◽  
Buffer Solution ◽  
Composite Surface ◽  
Biological Compatibility

The aim of this work is to evaluate the effect of chitosan content (1, 3 and 5 wt %) dispersed in polylactic acid (PLA) on the structure and properties of composites. Also, the hydrolytic degradation, and the cell viability and adhesion of human MG-63 osteoblasts are analyzed to determine the composites’ suitability for use in tissue engineering. For the manufacture of the materials, natural chitosan was extracted chemically from shrimp exoskeleton. The composites were fabricated by extrusion, because it is a low-cost process, it is reproducible, and it does not compromise the biocompatibility of the materials. FT-IR and XRD show that the chitosan does not change the polymer structure, and interactions between the composite components are discarded. In vitro degradation tests show that the composites do not induce significant pH changes in phosphate buffer solution due to their low susceptibility to hydrolytic degradation. The adhesion and morphological characteristics of the osteoblasts are evaluated using confocal microscopy and scanning electron microscopy. The cell viability is determined by the MTT assay. Osteoblasts adhesion is observed on the surface of PLA and composites. A higher amount of chitosan, higher number of cells with osteoblastic morphology, and mineralized nodules are observed on the composite surface. The highest metabolic activity is evidenced at 21 days. The results suggest that the Polylactic acid/chitosan composites are potentially suitable for use as a biomaterial.

scholarly journals In Vitro Biodegradation Pattern of Collagen Matrices for Soft Tissue Augmentation

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2633
Author(s):  
Cristina Vallecillo ◽  
Manuel Toledano-Osorio ◽  
Marta Vallecillo-Rivas ◽  
Manuel Toledano ◽  
Raquel Osorio
Keyword(s):  
Soft Tissue ◽  
Hydrolytic Degradation ◽  
Phosphate Buffer Solution ◽  
Soft Tissue Augmentation ◽  
Buffer Solution ◽  
Collagen Matrices ◽  
Bacterial Collagenase ◽  
Tissue Augmentation ◽  
Tissue Grafts

Collagen matrices have become a great alternative to the use of connective tissue grafts for soft tissue augmentation procedures. One of the main problems with these matrices is their volume instability and rapid degradation. This study has been designed with the objective of examining the degradation of three matrices over time. For this purpose, pieces of 10 × 10 mm2 of Fibro-Gide, Mucograft and Mucoderm were submitted to three different degradation tests—(1) hydrolytic degradation in phosphate buffer solution (PBS); (2) enzyme resistance, using a 0.25% porcine trypsin solution; and (3) bacterial collagenase resistance (Clostridium histolyticum)—over different immersion periods of up to 50 days. Weight measurements were performed with an analytic microbalance. Thickness was measured with a digital caliper. A stereomicroscope was used to obtain the matrices’ images. ANOVA and Student–Newman–Keuls tests were used for mean comparisons (p < 0.05), except when analyzing differences between time-points within the same matrix and solution, where pair-wise comparisons were applied (p < 0.001). Fibro-Gide attained the highest resistance to all degradation challenges. The bacterial collagenase solution was shown to constitute the most aggressive test as all matrices presented 100% degradation before 14 days of storage.

scholarly journals In Vitro Degradation of Plasticized PLA Electrospun Fiber Mats: Morphological, Thermal and Crystalline Evolution

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2975
Author(s):  
Adrián Leonés ◽  
Laura Peponi ◽  
Marcela Lieblich ◽  
Rosario Benavente ◽  
Stefano Fiori
Keyword(s):  
Lactic Acid ◽  
Electrospun Fiber ◽  
Hydrolytic Degradation ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
In Vitro Test ◽  
Fiber Mats ◽  
Whole Process ◽  
Vitro Test

In the present work, fiber mats of poly(lactic acid), PLA, plasticized by different amounts of oligomer lactic acid, OLA, were obtained by electrospinning in order to investigate their long term hydrolytic degradation. This was performed in a simulated body fluid for up to 352 days, until the complete degradation of the samples is reached. The evolution of the plasticized electrospun mats was followed in terms of morphological, thermal, chemical and crystalline changes. Mass variation and water uptake of PLA-based electrospun mats, together with pH stability of the immersion media, were also studied during the in vitro test. The results showed that the addition of OLA increases the hydrolytic degradation rate of PLA electrospun fiber mats. Moreover, by adding different amounts of OLA, the time of degradation of the electrospun fiber mats can be modulated over the course of a year. Effectively, by increasing the amount of OLA, the diameter of the electrospun fibers decreases more rapidly during degradation. On the other hand, the degree of crystallinity and the dimension of the α crystals of the electrospun fiber mats are highly affected not only by the presence but also by the amount of OLA during the whole process.

scholarly journals A Slow-Release Fertilizer of Urea Prepared via Melt Blending with Degradable Poly(lactic acid): Formulation and Release Mechanisms

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1856
Author(s):  
Mujtahid Kaavessina ◽  
Sperisa Distantina ◽  
Esa Nur Shohih
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Slow Release ◽  
Release Kinetics ◽  
Nutrient Balance ◽  
Hydrolytic Degradation ◽  
Poly Lactic Acid ◽  
Release Process ◽  
Slow Release Fertilizer ◽  
Micro Holes

In this research, a low molecular weight poly(lactic acid) (or PLA) synthesized from direct polycondensation was melt compounded with urea to formulate slow-release fertilizer (SRF). We studied the influence of the molecular weight (MW) of PLA as a matrix and the urea composition of SRF towards release kinetics in water at 30 °C. The physical appearance of solid samples, the change in urea concentration, and acidity (pH) of water were monitored periodically during the release test. Three studied empirical models exhibited that diffusion within the matrix dominated the urea release process, especially when the release level was less than 60%. Thus, a lower MW of PLA and a higher urea content of SRF showed a faster release rate. For the entire length of the release experiment, a combination of diffusion and degradation mechanisms exhibited the best agreement with the experimental data. The hydrolytic degradation of PLA may begin after 96 h of immersion (around 60% release level), followed by the appearance of some micro-holes and cracks on the surface of the SRF samples. Generally, this research revealed the good release performance of urea without residues that damage the soil structure and nutrient balance.

scholarly journals In Vitro and In Vivo Biosafety Analysis of Resorbable Polyglycolic Acid-Polylactic Acid Block Copolymer Composites for Spinal Fixation

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 29
Author(s):  
Seung Kyun Yoon ◽  
Jin Ho Yang ◽  
Hyun Tae Lim ◽  
Young-Wook Chang ◽  
Muhammad Ayyoob ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Animal Experiments ◽  
Polymeric Materials ◽  
Polyglycolic Acid ◽  
Poly Lactic Acid ◽  
Skin Sensitization ◽  
Spinal Fixation ◽  
In Vivo Degradation

Herein, spinal fixation implants were constructed using degradable polymeric materials such as PGA–PLA block copolymers (poly(glycolic acid-b-lactic acid)). These materials were reinforced by blending with HA-g-PLA (hydroxyapatite-graft-poly lactic acid) and PGA fiber before being tested to confirm its biocompatibility via in vitro (MTT assay) and in vivo animal experiments (i.e., skin sensitization, intradermal intracutaneous reaction, and in vivo degradation tests). Every specimen exhibited suitable biocompatibility and biodegradability for use as resorbable spinal fixation materials.

Bacterial chemotaxis to fungal propagules in vitro and in soil

1983 ◽  
Vol 29 (9) ◽  
pp. 1104-1109 ◽  
Author(s):  
D. K. Arora ◽  
A. B. Filonow ◽  
J. L. Lockwood
Keyword(s):  
Sandy Loam ◽  
Phosphate Buffer Solution ◽  
Bacterial Chemotaxis ◽  
Macrophomina Phaseolina ◽  
Buffer Solution ◽  
Erwinia Herbicola ◽  
Cochliobolus Victoriae ◽  
Fungal Propagules ◽  
Loam Soil

Erwinia herbicola, Pseudomonas fluorescens, and P. putida were strongly attracted in vitro to substances exuded by conidia of Cochliobolus victoriae and sclerotia of Macrophomina phaseolina, but not to phosphate buffer solution. Numbers of bacteria attracted to propagules of C. victoriae or M. phaseolina in an unsterilized sandy loam soil were significantly (P = 0.05) greater than background populations occurring in soil saturated with buffer. Chemotactic response was greater to C. victoriae than to M. phaseolina both in vitro and in soil. Results suggest that living fungal propagules may act as attractants for motile bacteria in soil.

Surface Morphological Changes Accompanying Dissolution of Bioactive Glass: Effect of Residual Stress

2008 ◽  
Vol 47-50 ◽  
pp. 1302-1306 ◽  
Author(s):  
John A. Nychka ◽  
Ding Li
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Bioactive Glass ◽  
Morphological Changes ◽  
Phosphate Buffer Solution ◽  
Buffer Solution ◽  
Mechanochemical Effect ◽  
Dissolution Behaviour ◽  
Glass Surfaces

We report our observations concerning the time evolution of surface morphology occurring during the in vitro immersion of bioactive glass surfaces in contact with phosphate buffer solution. We compare regions under intentionally produced residual stresses via micro-indentation to those where no indentation was performed. The sign of the residual stress is shown to be important for predicting dissolution behaviour; compression retards dissolution, whereas tension enhances dissolution. We analyze our results with a simple model for the work of bond dissociation. We report that a highly constrained residual compressive stress state, such as in an indent, leads to a work deficit in comparison to tension, which accounts for the slower dissolution rate of compressed bioactive glass. Such a mechanochemical effect suggests that the presence of residual stresses from the manufacture of biomedical implants and devices could lead to accelerated or delayed dissolution and that careful control of residual stresses should be sought for predictable performance in dissolvable materials.

Morphological behaviour of poly(lactic acid) during hydrolytic degradation

2008 ◽  
Vol 93 (10) ◽  
pp. 1964-1970 ◽  
Author(s):  
Xiaoqing Zhang ◽  
Maria Espiritu ◽  
Alex Bilyk ◽  
Lusiana Kurniawan
Keyword(s):  
Lactic Acid ◽  
Hydrolytic Degradation ◽  
Poly Lactic Acid
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