I often get questions about how to use PLGA-PEG Maleimide (Polyvivo AI03/AI20). A recent paper describes the usage of a similar-inhouse prepared polymer including how to react via cysteine and how this improves BBB permeation.
"The relative impermeability of the blood-brain barrier (BBB) results from tight junctions and efflux transport systems limits drug delivery to the central nervous system (CNS), and thus severely restricts the therapy of many central nervous system diseases. In order to enhance the brain-specific drug delivery, we employed a 12-mer phage display peptide library to isolate peptides that could target the drug delivery system to the brain. A 12-amino-acid-peptide (denoted as Pep TGN) which was displayed by bacteriophage Clone 12-2 was finally selected by rounds of in vivo screening. Pep TGN was covalently conjugated onto the surface of poly (ethyleneglycol)-poly (lactic-co-glycolic acid) (PEG–PLGA) based nanoparticles (NPs). The cellular uptake of Pep TGN decorated nanoparticles was significantly higher than that of unmodified nanoparticles when incubated with bEnd.3 cells. Enhanced brain accumulation efficiency together with lower accumulation in liver and spleen was observed in the nude mice intravenously injected with Pep TGN conjugated nanoparticles compared with those injected with plain nanoparticles, showing powerful brain selectivity of Pep TGN. Coumarin 6 was used as a fluorescent probe for the evaluation of brain delivery properties. The brain Drug Targeting Index (DTI) of coumarin 6 incorporated in targeted nanoparticles was significantly higher than that of coumarin 6 incorporated in plain nanoparticles. In conclusion, the Pep TGN is a motif never been reported before and Pep TGN modified nanoparticles showed great potential in targeted drug delivery across the blood brain barrier."
See http://dx.doi.org/10.1016/j.biomaterials.2011.03.031 to learn more
 Jingwei Li, Liang Feng, Li Fan, Yuan Zha, Liangran Guo, Qizhi Zhang, Jun Chen, Zhiqing Pang, Yuchen Wang, Xinguo Jiang, Victor C. Yang, Longping Wen, Targeting the brain with PEG–PLGA nanoparticles modified with phage-displayed peptides, Biomaterials, Volume 32, Issue 21, July 2011, Pages 4943-4950, ISSN 0142-9612, 10.1016/j.biomaterials.2011.03.031.
Keywords: Phage display; Blood-brain barrier (BBB); Brain delivery; Biodegradable nanoparticle)