Properties of Poly (Lactic-co-Glycolic Acid) and Progress of Poly (Lactic-co-Glycolic Acid)-Based Biodegradable Materials in Biomedical Research

Abstract

In recent years, biodegradable polymers have gained the attention of many researchers for their promising applications, especially in drug delivery, due to their good biocompatibility and designable degradation time. Poly (lactic-co-glycolic acid) (PLGA) is a biodegradable functional polymer made from the polymerization of lactic acid (LA) and glycolic acid (GA) and is widely used in pharmaceuticals and medical engineering materials because of its biocompatibility, non-toxicity, and good plasticity. The aim of this review is to illustrate the progress of research on PLGA in biomedical applications, as well as its shortcomings, to provide some assistance for its future research development.

Keywords: PLGA; applications; biodegradable; drug delivery; synthesis.

Figure 1

The synthesis of PLGA in Escherichia coli. Black arrows indicate the native pathways in E. coli; red arrows indicate heterologous pathways for polymerization of various monomers; pink, purple and orange arrows and shading indicate biosynthetic pathways for the generation of 2-hydroxyisovalerate CoA (2HIV-CoA), 3-hydroxybutyrate CoA (3HB-CoA) and 4-hydroxybutyrate CoA (4HB-CoA), respectively; blue arrows indicate the Dahms pathway. X-marks indicate inactivated metabolic pathways; bold arrows indicate metabolic pathways strengthened by replacement of native promoter. Dotted arrows indicate pathways that have been simplified from more than one conversion step. G6P, glucose 6-phosphate; F1,6BP, fructose-1,6-bisphosphate; PEP, phosphoenolpyruvate; Succinate SA, succinate semialdehyde; Ac-CoA, acetyl-CoA; LA, D-lactate; GA, glycolate; 2KIV, 2-ketoisovalerate [17]. Copyright 2016, Springer Nature.

Figure 2

(A), Comparison of PLGA degradation rates under different pH conditions [30]. Copyright 2008, Wiley. (B), Comparison of PLGA degradation rates for different monomer ratios [31]. Copyright 2010, Springer Nature. (C), Comparison of the degradation rates of PLGAs with different intrinsic viscosities; the magnitude of the intrinsic viscosities of the four PLGAs is P < L < E < M [32]. Copyright 2022, Elsevier.

Figure 3

Effect of PLGAq on the induction of apoptosis in MCF-7 cell line detected by Annexin V-FITC and PI double-staining method. At a concentration of 1.5 μg, the early and late apoptosis rates of PLGA microspheres were 5% and 2.36% respectively; at a concentration of 3.0 μg, the early and late apoptosis rates of PLGA microspheres were 10.38% and 4.83% respectively. At a PLGAq concentration of 1.5 μg, 35.70% and 9.94% apoptosis (early and late) was observed. When the concentration was increased to 3.0 μg, the apoptosis rate (early stage) was 53.37% and 6.78% in the late stage. A significant increase in the number of apoptotic cells was observed with increasing concentrations of PLGAq after administration. [45]. Copyright 2019, Elsevier.

Figure 4

Concentrations of selegiline in rat brain tissue after administration of different dosage forms, SPNP is a selegiline PLGA nanoparticle, SLPNP is a Phospholipon^® 90 G modified selegiline PLGA nanoparticle [51]. Copyright 2022, Elsevier.

Figure 5

Phagocytosis of MPs by macrophages at 24 h (a) and 48 h (b). The red circles indicate that MPs do not influence macrophages to replicate while inside the cell [57]. Copyright 2020, Springer Nature.

Figure 6

HACC–PLGA/HA composite scaffold in cortical bone defects in rats and hairy bone defects in rabbits [68]. Copyright 2018, Elsevier.

Figure 7

Collagen matrix contraction assay. (A) Collagen matrix contraction images. (B) Quantitative data of collagen contraction. n = 5; * p < 0.05: significant difference from the control group; ^# p < 0.05: significantly different from the PLG–Adasatinib group [76]. Copyright 2019, Elsevier.

Figure 8

Dual-modal PA and MRI imaging ability of magnetic PLGA-IO MPs. Qualitative observations show an enhanced PA signal with increasing iron content in the particles and a low signal on MRI [84]. Copyright 2018, Public Library of Science.

Figure 9

The biocompatibility study of TGF-β1/PLGA MPs with rat islet cells, (A) control islets, (B) islets incubated with TGF-β1 PLGA microparticles, (C) islets incubated with soluble TGF-β1, Red = dead cells, Green = viable cells [90]. Copyright 2021, Frontiers.

Figure 10

Inhibitory ability of different doses of licochalcone-A on ocular inflammation [96]. Copyright 2022, MDPI.

Figure 11

Effect of QβS100A9 vaccine implantation on atherosclerosis in mice on a high-fat diet, (A) Body weight (grams), (B) The concentration of total cholesterol in plasma., (C) The presence of atherosclerotic plaques shown as the percentage of lesion determined by oil red O staining., (D) Plasma concentrations of calprotectin, (E) Plasma concentrations of MCP-1, (F) Plasma concentrations of IL-6, (G) Plasma concentrations of IL-1β. Data are means ± SEM (n = 10), unpaired two-tailed t-test, 95% confidence value, p < 0.05 was considered the threshold for statistical significance versus control group [99]. Copyright 2022, Wiley.

Figure 12

In vivo antibacterial effect of RPTR-701 NPs on MRSA-infected mice, (A) Schematic diagram of MRSA-infected model establishment and treatment plan, (B) Wound skin after treated with PBS, TR-701, PTR-701Ns and RPTR-701Ns, (C) Relative change in the wound area, (D) LB culture pates of different groups of skin, (E) Quantitative analysis of bacteria colony, Data were presented as mean * p < 0.1, ** p < 0.01, *** p < 0.001, **** p < 0.0001 [106]. Copyright 2021, MDPI.