(4) Various additives complexing with PLGA with increased drug loading and/or sustained release profiles
Additives	Encapsulated drug	Drug loading or EE	Drug release profile	References
POE/PLGA	BSA	9–11% and EE 60–90%	95% over 30 days	Shi et al., 2003
POE/PLGA	Cyclosporin A	6–10% and EE 60–90%	14% over 15 days followed by 78% over the next 27 days	Shi et al., 2003
Alginate and chitosan-PLGA double walled	BSA	EE at 75% c.f. 65% compared with single-walled systems	5–10% in 30 min c.f. 30% for single-walled systems	Zheng and Liang, 2010
Alginate-PLGA double walled	Metoclopramide HCl	EE increase from 30% to 60% c.f. single walled system	Improved release profile	Lim et al., 2013
4% w/w chitosan/PLGA	Resveratrol	EE 40–52% Particle size: 11 to 20 μm and more stable	Improved controlled release	Sanna et al., 2015
Caffeic acid grafted PLGA (g-CA-PLGA)	Ovalbumin	EE increased from 35 to 95% c.f. PLGA alone (size 15–50 μm)	Unchanged	Selmin et al., 2015
Mixed copolymer of PLGA 50:50 (Mr 100,000 and 14,000) 1:7	Pentamidine	23.7%, whereas only 9.8 and 13.9 %, when prepared with either of them alone	Produced microcapsules with desired release profiles	Graves et al., 2004
Aqueous core-PLGA shell	Risedronate sodium	2.5-fold increase: 31.6% c.f. 12.7% for classical PLGA microspheres	Sustained release according to diffusion-controlled Higuchi model	Abulateefeh and Alkilany, 2015
Porous silicon oxide (pSiO2)-PLGA	Daunorubicin	Slightly increased loading (3.1–4.6%) c.f. 2.7% for PLGA-daunorubicin microspheres	A 2-5 fold longer duration of release c.f. PLGA-daunorubicin microspheres	Nan et al., 2014

BSA, Bovine serum albumin; EE, Encapsulation efficiency; hGH, Human growth hormone; M_r, Molecular weight; OHR1031, a small molecule for the treatment of glaucoma; PLA, poly(lactic acid); PLGA, poly(lactic-co-glycolic acid); POE, poly(ortho esters).