Preparation and characterization of poly(propylene glycol)-conjugated cationic polymers for effcient gene delivery

Gyeonghui Yu,Minji Kang,Hyejung Mok

Department of Bioscience and Biotechnology,Konkuk University,Seoul 143-701,Republic of Korea

Preparation and characterization of poly(propylene glycol)-conjugated cationic polymers for effcient gene delivery

Gyeonghui Yu,Minji Kang,Hyejung Mok*

Department of Bioscience and Biotechnology,Konkuk University,Seoul 143-701,Republic of Korea

A R T I C L E I N F O

Article history:

Available online 25 November 2015

Branched polyethylenimine

Micelle

Thermosensitive

ε-Poly-L-Lysine(ε-PLL)

Nucleic acid drugs are desirable therapeutics for the treatment of fatal diseases like cancers.For clinical translation of nucleic acid drugs,carrier systems that protect nucleic acid from degradation and help cellular uptake are needed.Accordingly cationic polymers are used as a carrier due to their strong electrostatic interaction with nucleic acids,which produce nanosized particles[1].

In this study,branched polyethyleneimine(BPEI,25 kDa)and ε-Poly-L-Lysine(ε-PLL)were conjugated with a temperatureresponsive polymer,poly(propylene glycol)(PPG),to prepare biocompatible and temperature responsive cationic polymer for gene delivery.Terminal hydroxyl groups of PPG was activated with 1,4-nitrophenyl chloroformate(NPC)to prepare PPG–NPC,which then reacted with primary amine groups of BPEI to produce BPEI–PPG conjugate.Degree of NPC modifcation in PPG–NPC was quantitatively analyzed by measurement of absorbance at a wavelength of 410 nm.Approximately one NPC per single PPG was successfully conjugated.After reaction BPEI with PPG–NPC,the extent of PPG conjugation per BPEI was analyzed by fuorescamine assay.Also,modifcation of primary amine in conjugates was quantifed by fuorescamine assay using ε-PLL as a standard.Absorbance of conjugates in 1%tritonx100 1XPBS solution was measured at 390–475 nm.Solubility of BPEI–PPG in deionized water(DW)was examined by measuring transmission of polymer solutions at a wavelength of 400 nm after incubation at different temperatures,4°C and 37°C.Transmission of polymer solutions at 37°C was signifcantly lower than that at 4°C.In addition,BPEI–PPG exhibited the reversible transition behaviors as changing temperature, which suggests that BPEI–PPG might form micelles through hydrophobic interactions in a thermo-sensitive manner.The complexation of PLL–PPG conjugates and DNA was verifed by 1%agarose gel analysis to confrm encapsulation of DNA in conjugates[2,3].

We synthesized and characterized poly(propylene glycol)-conjugated cationic polymers,which showed excellent temperature sensitivity in aqueous solution.This novel cationic copolymer might be applied for thermo-responsive gene delivery after biological evaluations including biocompatibility and binding assays with genes.

Fig.1–(A)Quantitative analysis of amine modifcation after PPG conjugation to poly-L-lysine(PLL).(B)Temperature responsiveness of PPG conjugated cationic polymers.(C)Gel retardation of PPG conjugated PLL polyelectrolyte complexes.

R E F E R E N C E S

[1]Zhu L,Mahato RI.Lipid and polymeric carrier-mediated nucleic acid delivery.Expert Opin Drug Deliv 2010;7:1209–1226.

[2]Wiegand C,Bauer M,Hipler UC,et al.Poly(ethyleneimines)in dermal applications:biocompatibility and antimicrobial effects.Int J Pharm 2013;456:165–174.

[3]Schmljohann D.Thermo-and pH-responsive polymers in drug delivery.Adv Drug Deliv Rev 2006;58:1655–1670.

*E-mail address:hjmok@konkuk.ac.kr.

Peer review under responsibility of Shenyang Pharmaceutical University.

http://dx.doi.org/10.1016/j.ajps.2015.11.063

1818-0876/©2016 Production and hosting by Elsevier B.V.on behalf of Shenyang Pharmaceutical University.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).