Poly-L-lactic acid microsphere

Liggins RT, Burt HM (2001) Paclitaxel loaded poly(L-lactic acid) microspheres properties of microspheres made with low molecular weight polymers. Int J Pharm 222 19-33... 

Masinde, L. and Hickey, A.J. (1993). Aerosolized aqueous suspensions of poly(L- lactic acid) microspheres. Int. J. Pharmaceut., 100, 123-131. 

Seki, T., Kawaguchi, T., et al. Controlled release of 3, 5 -diester prodrugs of 5-fluoro-2 -deoxyuridine from poly-L-lactic acid microspheres. J. Pharm. Sci. 79(ll) 985-987,1990. 

El-Baseir MM, Kellaway IW. Poly(L-lactic acid) microspheres for pulmonary drug delivery release kinetics and aerosolisation studies. Int J Pharm 1998 175 135-145. 

T. He, Q. Liang, K. Zhang, X. Mu, T. Luo, Y. Wang, and G. Luo, A modified microfluidic chip for fabrication of paclitaxel-loaded poly(L-lactic acid) microspheres. Microfluidics and Nanofluidics, 10, 1289-1298, 2011. 

Liggins, R. T., D Amours, S., Demetrick, J. S., Machan, L. S. Burt, H. M. (2000) Paclitaxel loaded poly(L-lactic acid) microspheres for the prevention of intraperitoneal carcinomatosis after a surgical repair and tumor cell spill. Biomaterials, 21, 1959-69. 

Pandit, S., Cevher, E., Zariwala, M.G., Somavarapu, S., and Alpar, H.O. 2007. Enhancement of immune response of HBsAg loaded poly (L-lactic acid) microspheres against hepatitis B through incorporation of alum and chitosan. J. Microencapsul. 24 539-552. 

Yamamoto T, Hayakawa K, et al. (2003) Transcatheter arterial embolization using poly-L-lactic acid microspheres. Radiat Med 21 150-154... 

D. J. Armstrong, P. N. Elliott, J. L. Ford, D. Gadsdon, G. P. McCarthy, C. Rostron, and M. D. Worsley, Poly-(D,L-lactic acid) microspheres incorporating histological dyes for intra-pulmonary histopathological studies, J. Pharm. Pharmacol. 48 259 (1996). 

Microspheres containing a corona of polyphosphobetaines were obtained by emiflsifier-free emulsion copolymerization of methyl methacrylate and l-methyl-2-methacrylamidoethyl phosphorylcholine [132], MPC [133], or the fumarate monomers of 40 [133], as well as by precipitation polymerization of styrene with MPC macromonomers [134]. Poly-L-lactic acid nanoparti-... 

In this paper, we have successfully synthesized Ca-doped mesoporous materials CaMCM-41. Subsequently, the composite microspheres based on CaMCM-41 and poly(L-lactic acid) (CaMCM-41/PLLA) were also prepared by a solid-in-oil-in-water (s/o/w) emulsion/solvent evaporation technique. Gentamicin was absorbed into the microspheres to obtain a drug delivery system. In vitro release behaviors of gentamicin were evaluated in PBS solution at 37 °C. In addition, the degradation of CaMCM-41 incorporated in the composite microspheres was also investigated. 

In one study, the degradation of double-walled microspheres with a core of poly(l,3-bis-(p-carboxyphenoxypropane)-co-(sebacic anhydride)) 20 80 (P(CPP SA)20 80) and an external coat of poly(L-lactic acid) (PLL A) was monitored in vitro and in vivo for 6 months. The inner core of the more hydrolytically labile P(CPP SA) 20 80 degraded first, while the shell layer remained relatively intact. 

Figure 73 Representative 3-D nanostructured scaffolds for bone-specific drug delivery systems, (a) Electrospun sitk scaffold with BMP-2 loaded, scale bar=5 pm (reprinted from Ref. [86] with permission) (b) Self-assembled peptide-amphiphile (PA) nanofibers network, scale bar= 1 mi (reprinted from Ref. [87] with permission) (c) Nanocrystalline apatite modified poly(lactide-co-glycolide) (PLAGA) microsphere scaffolds, scale bar=2pm (reprinted from Ref. [88] with permission) and (d) poly(L-lactic acid) (PLLA) nanofibrous scaffolds incorporated with poly(lactic-co-glycolic acid) (PLGA) nanospheres, scale bar=2 pm (reprinted from Ref. [89] with permission).

The protein-polymer microcapsules can be obtained by supercritical anti-solvent techniques [8]. Homogeneous protein-polymer mixtures were contacted with supercritical carbon dioxide in order to produce microspheres with diameter ranging from 1 to 5 pm and containing around 80% of protein. Production of PLA microparticles containing insulin, lysozyme, and chemotrypsin is claimed. SAS crystallization of a pharmaceutical (naproxen) and a biodegradable poly(L-lactic acid) was reported [8]. The results from SAS studies showed very small spherical particles... 

Poly-L-lactic acid (PLLA) microspheres have also been tested for transcatheter delivery, but they are biodegradable and tend to clog microcatheters, like PVA particles. The diameter of these particles can be changed according to the polymerization time and therefore, various sizes of PLLA microspheres can be prepared [74]. Loading of these particles with neutron-activated radioactive holmium 166 ( Ho) has also been tested for transcatheter administration in an animal HCC model [49]. A recent study demonstrated that the Ho on the surface of neutron-irradiated Ho-PLLA-micro-... 

Figure 12 Fluorescence (left) and transmission (right) images of poly(L-lactic acid)-pyrene microspheres precipitated at pyrene concentrations in CO2 of (top) 0.0013 wt % and (bottom) >0.002 wt %. (From Ref. 101.)...

T.G. Park, Degradation of poly(d,l-lactic acid) microspheres effect of molecular weight. Journal of Controlled Release, 30 (2) 161-173,1994. 

Park,T. G., Lu, W., and Crotts, G. (1995), Importance of in vitro experimental conditions on protein release kinetics, stability and polymer degradation in protein encapsulated poly(D,L-lactic acid-co-glycolic acid) microspheres,/. Controlled Release, 33,211-222. 

For drugs which are soluble in SC CO2, the SC fluid can be expanded info air, or info a solufion containing polymers and other additives, such as phospholipids or Tween 80.1 By varying depressurization, the product can be formed as very fine particles, fibers, thin films, or as biodegradable polymeric microspheres containing drug. Typical biodegradable polymers which are soluble in the SC fluid include poly(hydroxyacid) and poly(D,L-lactic acid). Scale-up has been complicated... 

Iwata M, McGinity JW. Preparation of multi-phase microspheres of poly(D,L-lactic acid) and poly(D,L-lactic co-glycolic acid) containing a w/o emulsion by a multiple emulsion solvent evaporation technique. / Microencapsul 1992 9(2) 201-214. 

Drug delivery microspheres, in particular smart systems with controlled release, have been developed with PLA and its copolymers with glycolide to produce poly[(D,L-lactic acid)-co-(glycolic acid)]. Since the 80 s up until the present, many publications have reported on the various applications in the pharmaceutical field for using PLA and copolymers and polymers for their sustained release parenteral formulations and performance in drug release in a controlled manner from microspheres [200, 201]. 

Burt H, Jackson J, Bains S, Liggins R, Oktaba A, Arsenault A, Hunter W. Controlled delivery of taxol from microspheres composed of a blend of ethyle-nevinyl acetate copolymer and poly(d,l-lactic acid). Cancer Lett 1995 88 73-79. 

Microspheres based on poly(d,l-lactic acid) (PLA) and its copolymer with glycolic acid (poly-d,l-lactic-co-glycolic acid or PLGA) as protein delivery systems have been deeply studied [6,50,52]. 

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