Construction Of Gene Delivery Systems Based On Near-infrared Photothermal Conversion Nanomaterials

How to design safe and effective non-viral vector is the key point in gene therapy.Therapeutic gene needs to be delivered into target cells and express,realizing gene transfection.During this,the physicochemical properties of gene-loaded complexes,such as their morphology and size,will influence their biological properties,and further affect gene transfection efficiency.Meanwhile,to achieve high gene transfection,ideal gene carriers must overcome multiple extra-and intracellular barriers.In this work,we developed several gene carriers based on gold and polydopamine nanoparticles to investigate the influences of their sizes,morphologies or stimuli-responsive abilities on gene transfection efficiency.And by using their near-infrared(NIR)photothermal conversion ability,the mechanism of photothermally promoted gene delivery and synergistic gene/photothermal therapy were further studied.Firstly,we modified gold nanospheres and gold nanorods with polyethyleneimine-g-bovine serum albumin to prepare spherical gene carriers Au NS@BSA-PEI and rod-like gene carriers Au NR@BSA-PEI,and then studied the influence of morphology on gene delivery.After loading gene,the obtained complexes could remain the morphology.The rod-like Au NR@BSA-PEI/DNA complexes showed higher cellular internalization efficiency and better gene transfection result than spherical Au NS@BSA-PEI/DNA complexes in vitro.At the N/P ratio of 20,Au NR@BSA-PEI/DNA complexes demonstrated almost 100 times higher RLU value in gene transfection test.And moreover,since gold nanorod has good near-infrared photothermal conversion ability,those rod-like carriers were promising in synergistic gene/photothermal therapy.Secondly,we prepared polyethylenimine-polydopamine nanoparticles(PPNP)to investigatethe influence of size on gene delivery.SPPNP with the average diameter of 10 nm and LPPNP with the average diameter of 190 nm were obtained.Those carriers could condense gene effectively and form spherical gene-loaded complexes.The formed SPPNP/DNA complexes demonstrated average diameters of 50-70 nm and LPPNP/DNA were around 190 nm.At the mass ratio(PPNP to gene)of 23 or 30,both SPPNP/DNA and LPPNP/DNA complexes presented higher transfection level than lipofectamine/DNA complexes.Because of higher specific surface area,SPPNP/DNA complexes showed higher cellular internalization efficiency than LPPNP/DNA complexes.However,gene transfection level of SPPNP/DNA complexes was lower.Under NIR light irradiation,the photothermal effect of polydopamine nanoparticles could disrupt endosomal membrane,lead to fast endosomal escape of gene complexes.The transfection efficiency of both SPPNP/DNA and LPPNP/DNA complexes was further improved.Ideal non-viral gene delivery systems must overcome multiple extra-and intracellular delivery barriers and release gene effectively in target cells.To achieve this,we modified polydopamine nanoparticles with polyethylene glycol-phenylboronic acid and low-molecular weight polyethylenimine to prepare the p H-responsive gene carrier PDANP-PEI-r PEG.Non-responsive carrier PDANP-PEI-n PEG and non-PEGylated carrier PDANP-PEI were also developed as control.PEG shell could improve the stability of gene complexes.Under the acidic p H environment inside endosomes,the boronate ester bonds were cleaved to detach the PEG shell,which facilitated the gene complexes quickly escape from the endosome to transfection.At the same assembly condition,the transfection level of the PDANP-PEI-r PEG/DNA complexes was about 100 times higher than that of PDANP-PEI-n PEG/p GL-3 complexes.Under NIR light irradiation at the power density of 2.6 W/cm~2 for 20 min,the transfection levels of PDANP-PEI-r PEG/DNA complexes doubled,higher than commercial lipofectamine/DNA complexes.Lastly,the NIR photothermal conversion ability of polydopamine nanoparticles could also be used in synergistic gene/photothermal therapy.We loaded LPPNP with tumor suppress p53 gene and studied their synergistic therapy efficieny in vitro and in vivo.After intratumoral injected into tumor-bearing mice,the synergistic therapy could almost completely remove the tumor,with a tumor suppression rate of 99%.Synergistic gene/photothermal therapy had better treatment efficiency than gene therapy or photothermal therapy alone.By modulating the morphology,size and stimuli-responsive ability,non-viral gene complexes were optimized.And due to the good photohermal conversion ability,the gold nanoparticles and polydopamine nanoparticles are promising for synergistic PTT/gene therapy in cancer treatment.