PLGA is a linear copolymer of LA and GA. By changing the ratio of LA to GA, the mechanical properties and degradation properties of PLGA can be regulated. When the LA content increases, the hydrophobicity of the PLGA polymer increases, and the hydrolysis and biodegradation rates decrease; conversely, the hydrophilicity of the PLGA polymer increases, and the hydrolysis and biodegradation rates increase. The glass transition temperature of PLGA is between polyglycolic acid (PGA) and PLA, and the crystallinity varies with the ratio of LA to GA in the copolymer. PLGA is widely used in medical fields such as surgical sutures, drug sustained-release carriers, and tissue engineering due to its non-toxicity, good biocompatibility, and easy degradation in vivo.

Figure 1. Functions and applications of PLGA drug carriers. (Chereddy KK, et al. 2018)

PLGA nano drug delivery technology has important applications in tumor treatment. By encapsulating anti-tumor drugs in PLGA nanoparticles, the stability and bioavailability of drugs can be improved and the side effects of drugs can be reduced. PLGA nanoparticles can be taken up by tumor cells and release drugs into tumor cells, thereby improving the local efficacy of drugs. In addition, PLGA nano drug delivery technology can also achieve targeted drug delivery and improve the accumulation of drugs in tumor tissues by changing the properties of PLGA nanoparticles. Tumor-aggregating nanocarriers first pass through the high permeability and retention effect (ERP) of solid tumors. The microvascular endothelial gaps in normal tissues are dense and structurally intact, and macromolecules and lipid particles are not easy to penetrate the vascular wall. However, solid tumor tissues are rich in blood vessels, the vascular wall gaps are wide, the structural integrity is poor, and lymphatic return is absent, resulting in selective high permeability and retention of macromolecules and lipid particles. This phenomenon is called tumor enhanced permeability and retention effect, referred to as EPR effect. PLGA nanoparticles have the characteristics of good stability and long vascular circulation time, and are particularly suitable for passive targeted therapy of tumors. PLGA-encapsulated chemotherapy drugs, such as doxorubicin, paclitaxel, cisplatin, curcumin, etc., all adopt this passive targeted therapy strategy to increase anti-tumor activity, prolong circulation time, and avoid contact between drugs and blood to improve drug stability.

PLGA nano drug delivery technology has important applications in vaccine delivery. By encapsulating vaccine antigens in PLGA nanoparticles, the stability and immune effect of the vaccine can be improved, the vaccine can be stably encapsulated, the degradation and inactivation of the vaccine can be prevented, and the delivery efficiency and immune effect of the vaccine can be improved. By being taken up by immune cells, the vaccine antigens are released into the cells, the immune cells are activated, and the immune effect of the vaccine is improved. By changing the properties of PLGA nanoparticles, the targeted delivery of vaccines can be achieved, and the accumulation of vaccines in immune tissues can be improved. In addition, PLGA nano drug delivery technology also has important applications in bone tissue engineering. By encapsulating bone tissue engineering materials such as growth factors and cells in PLGA nanoparticles, the stability and bioactivity of the materials can be improved. PLGA nanoparticles can be taken up by bone cells, and growth factors, cells, etc. can be released into bone tissue to promote the growth and repair of bone tissue. In addition, PLGA nano drug delivery technology can also achieve targeted delivery of bone tissue engineering materials by changing the properties of PLGA nanoparticles, and realize the joint release of multiple materials, improve the growth and repair effect of bone tissue, and improve the accumulation of materials in bone tissue. It has significant therapeutic effects in bone regeneration, bone defect repair, and fracture healing. Depending on the type of polymeric biomaterial to be used and its intended application, crosslinking may be required to ensure the stability of the material under physiological conditions. The choice of crosslinking strategy also has a direct impact on the degradation behavior of the material, as some crosslinks are cleaved by enzymatic or hydrolytic mechanisms, thereby promoting degradation of the structure and potentially promoting structural reorganization. The crosslinker or chemical initiator added to the polymeric material must itself be biocompatible at specific doses or extractable prior to contact with living cells or tissues.

Alternate Names:
Poly(lactic-co-glycolic acid)

References:
1.    Chereddy KK, et al. PLGA: From a classic drug carrier to a novel therapeutic activity contributor. J Control Release. 2018, 289:10-13.

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