Controlled release of complexed DNA from polycaprolactone film: Comparison of lipoplex and polyplex release

Biotin-triggered release and transfection of DNA complexes immobilized on a substrate via biotin–avidin interaction

In this study, the highly specific biotin–avidin interaction was used to immobilize DNA complexes to a substrate. An excess of biotin was added to trigger the dissociation of DNA complexes from the substrate to mediate their release and transfection. Biotin-grafted-polyethyleneimine/DNA complexes with N/P ratio of 5 were prepared with diameter of 170.2 nm and ζ-potential of 16.1 mV. The DNA immobilized substrates were fabricated using a biotin–avidin–biotin sandwich model, which were characterized by atom force microscope and fluorescent microscope. Compared to DNA immobilization by physical adsorption, a higher DNA density of 935 ng/cm2 was observed on biotinylated substrates. Based on the in vitro release profiles, the DNA complexes immobilized on silanized substrate released faster than those on biotinylated substrate. Triggered by the addition of extra biotin, more DNA complexes were released. The transfection efficiencies of the DNA complexes immobilized on different substrates were assayed on HEK-293T cells. The highest transfection efficiency was obtained in the group of biotinylated substrate with the trigger of extra biotin. Thus, the system of demobilized DNA complexes onto a substrate by the biotin–avidin interaction and the dissociation of DNA complexes from a substrate triggered by the extra biotin provides a promising strategy for the realization of the controlled release and enhanced transgene expression of genes.

Poly-є-caprolactone based formulations for drug delivery and tissue engineering: A review

Biodegradable polymer based novel drug delivery systems have provided many avenues to improve therapeutic efficacy and pharmacokinetic parameters of medicinal entities. Among synthetic biodegradable polymer, poly-є-caprolactone (PCL) is a polymer with very low glass transition temperature and melting point. Owing to its amicable nature and tailorable properties it has been trialed in almost all novel drug delivery systems and tissue engineering application in use/investigated so far. This review aims to provide an up to date of drugs incorporated in different PCL based formulations, their purpose and brief outcomes. Demonstrated PCL formulations with or without drugs, intended for drug delivery and/or tissue engineering application such as microsphere, nanoparticles, scaffolds, films, fibers, micelles etc. are categorized based on method of preparation.

Core-sheath structured fibers with pDNA polyplex loadings for the optimal release profile and transfection efficiency as potential tissue engineering scaffolds

Emulsion electrospinning was initially applied to prepare core-sheath structured fibers with a core loading of pDNA or pDNA polyplexes inside a fiber sheath of poly(DL-lactide)-poly(ethylene glycol) (PELA). The inclusion of poly(ethylene imine) (PEI) and poly(ethylene glycol) (PEG) were expected to modulate the release profiles and achieve a balance between cytotoxicity and transfection efficiency. The core-sheath fibers enhance the structural integrity and maintain the biological activity of pDNA during the electrospinning process, incubation in release buffer and enzyme digestion. The addition of hydrophilic PEI into the fiber matrix accelerates pDNA release, while the encapsulation of pDNA polyplexes within the fibers led to no further release after an initial burst. However, sustained release of pDNA polyplexes has been achieved through PEG incorporation, and the effective release lifetime can be controlled between 6 and 25 days, dependent on the amount loaded and the molecular weight of PEG. Higher N/P ratios of PEI to DNA result in lower cell attachment, while cell viability is dependent on the effective concentration of pDNA polyplexes released from the fibers. While no apparent transfection is detected for pDNA-loaded PELA fibers, PEG incorporation into fibers containing pDNA polyplexes leads to over an order of magnitude increase in the transfection efficiency. pDNA polyplex-loaded fibers containing 10% PEG show the best performance in balancing transfection efficiency and cell viability. It is suggested that electrospun core-sheath fibers integrated with DNA condensation techniques provide the potential to produce inductive tissue engineering scaffolds able to manipulate the desired signals at effective levels within the local tissue microenvironment.