Versatile functionalization of amylopectin for effective biomedical applications

Successful gene vectors should be with high transfection efficiency and minimal cytotoxicity. Natural polysaccharides, due to their good biocompatibility and biodegradability, have been widely studied and applied. Amylopectin is one of polysaccharides with dendritic structure and numerous hydroxyl groups that could be used for subsequent modification. In this work, a series of dendritic cationic gene vectors comprising amylopectin backbones and poly(2-(dimethylamino) ethyl methacrylate)(PDMAEMA) side chains with different lengths(termed as AMY-PDs) were readily prepared by atom transfer radical polymerization(ATRP). The gene condensation ability, cytotoxicity and gene transfection of AMY-PDs carriers were investigated. In comparison with "gold-standard" poly(ethyleneimine)(PEI, 25 k Da), the AMY-PDs exhibited higher transfection efficiency with lower cytotoxicity. AMY-PDs could be further modified with Au nanoparticles(termed as AMY-PD@Au). The potential of the AMY-PD@Au vectors to be utilized as a CT contrast agent for imaging of cancer cells was investigated. Such AMY-PD@Au vectors may realize gene therapy with the ability of real-time imaging.

Facile synthesis of wormlike quantum dots-encapsulated nanoparticles and their controlled surface functionalization for effective bioapplications

Semiconductor quantum dots (QDs) are considered as ideal fluorescent probes owing to their intrinsic optical properties. It has been demonstrated that the size and shape of nanoparticles significantly influence their behaviors in biological systems. In particular, one-dimensional (1D) nanoparticles with larger aspect ratios are desirable for cellular uptake. Here, we explore a facile and green method to prepare novel 1D wormlike QDs@SiO2nanoparticles with controlled aspect ratios, wherein multiple QDs are arranged in the centerline of the nanoparticles. Then, an excellent cationic gene carrier, ethanolamine-functionalized poly(glycidyl methacrylate) (denoted by BUCT-PGEA), was in-situ produced via atom transfer radical polymerization on the surface of the QDs@SiO2nanoparticles to achieve stable surfaces (QDs@SiO2-PGEA) for effective bioapplications. We found that the wormlike QDs@SiO2-PGEA nanoparticles demonstrated much higher gene transfection performance than ordinary spherical counterparts. In addition, the wormlike nanoparticles with larger aspect ratio performed better than those with smaller ratio. Furthermore, the gene delivery processes including cell entry and plasmid DNA (pDNA) escape and transport were also tracked in real time by the QDs@SiO2-PGEA/pDNA complexes. This work realized the integration of efficient gene delivery and real-time imaging within one controlled 1D nanostructure. These constructs will likely provide useful information regarding the interaction of nanoparticles with biological systems. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.