Direct synthesis of poly(D,L‐lactic acid) by melt polycondensation and its application in drug delivery

Abstract

ABSTRACT:Starting from d,l-acid and SnCl 2 as catalyst, poly(d,l-lactic acid) (PDLLA) was directly synthesized by melt polycondensation. Under the appropriate conditions such as 0.5 wt % SnCl 2 , 170 -180°C, 70 Pa, and 10 h, the viscosity-average molecular weight (M ) of PDLLA was 4100 Da. PDLLA produced by the most practical method was used as the drug-delivery material for erythromycin and ciprofloxacin. The optimal conditions for the preparation of erythromycin-poly(d,l-lactic acid)-microsphere (ERY-PDLLA-MS) for lung targeting was investigated, and further confirmed by good reappearance tests. DSC and SEM demonstrated that ERY-PDLLA-MS had good spherical shape. The release in vitro of ERY-PDLLA-MS was effective and the half-time (T 1/2 ) was 51.0 h. After 175 h, the accumulated release percentage was 80.0%. The test in vivo showed that ERY-PDLLA-MS was more easily distributed in rabbit lung tissue. When PDLLA was applied in an antibacterial ciprofloxacin drug-delivery microsphere (CIP-P-DLLA-MS), CIP-PDLLA-MS was also characterized with DSC and SEM, and the release T 1/2 in vitro was 24.9 h. After 53.2 h, the accumulated release percentage reached 84.0%, which indicated that CIP-PDLLA-MS was advantageous to long-term release.

Synthesis of poly(D,L‐lactic acid) modified by triethanolamine by direct melt copolycondensation and its characterization

“…[20][21][22] The influences of different catalysts on reaction are shown in Table I, and the results are similar to those of the reported literatures. [12][13][14][15][16][20][21][22] Although the reaction catalyzed by zinc chloride (Table I, Run 3) gave the biggest yield (65.3%), the [g] was smaller than that using SnO as the catalyst (Run 2). Thus, SnO was selected for the following experiments because the catalyst was most likely to generate bigger molecular weight.…”

“…According to our previous research on the melt homopolymerization/copolymerization of LA, 3,6,[12][13][14][15][16] LA and TEA should be prepolymerized before copolymerization. After LA and TEA were uniformly mixed as preplanned molar feed ratio, the mixture was directly dehydrated for a preplanned time at 140 C under 4000 Pa in a flask equipped with mechanical stirring and thermometer.…”

“…In this article, based on our previous work on the direct melt polycondensation of LA, 3,6,[12][13][14][15][16] poly(lactic acid-co-triethanolamine) [P(LA-TEA)] was synthesized for the first time using TEA as a commoner for PLA (Scheme 1), and the copolymer was characterized by means of intrinsic viscosity ([g]), FTIR, 1 LA) (analytic reagent), were purchased from Guangzhou Chemical Reagent Factory (Guangzhou, China), and used without further purification.…”

Enzymes catalysing the synthesis and degradation of beta-linked biopolymers and their applications

“…PLAs are produced from renewable biomass through a chemo-bioprocess consisting of the fermentative production of lactic acid (LA) and chemical polymerization. LA is spontaneously polymerized by refluxing, but the molecular mass of the yielded polymer tends to be low [33]. There are several methods for synthesizing highmolecular-mass PLAs: condensation, chain elongation, and ring-opening polymerization of cyclic lactides [31].…”

Synthesis and characterization of a novel functional biodegradable material, poly(lactic acid-co-borneol)

“…Fortunately, lower or no crystallinity is more beneficial for PLA biodegradable materials to be applied in the biomedical fields, especially drug delivery carrier materials, because there will be no residual microcrystalline after degradation in vivo [27,34].…”