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We developed a composite wound dressing that provides multifunctional wound care. Alginate and polycaprolactone (PCL) were coelectrospun as composite fibers. Highly absorbent alginate provided a moist environment for wounds and PCL increased cell adhesion. Silver nanoparticles embedded in PCL fibers for long-term release inhibited the growth of microorganisms. In addition, plasmid DNA encoding platelet-derived growth factor-B (PDGF-B) were complexed with polyethylenimine (PEI) to form cationic nanoparticles which were then adsorbed on anionic alginate fibers through electrostatic interaction. As wound cells adhered to composite fibers, they were in situ transfected to express PDGF-B continuously. Moreover, calcium ions in alginate fibers were released into the wound site through ion exchange to accelerate hemostasis. Wound healing experiments demonstrated that PDGF-B gene-loaded composite fibers accelerated wound closure and promoted collagen formation. We expect this comprehensive study offers an ideal multifunctional solution to facilitate wound healing., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Cancer stem cells (CSCs) are potential platforms to high-throughput screen anti-cancer drugs. However, they are difficult to isolate from cancer cells. Therefore, we proposed to fabricate 3-D scaffolds for CSC enrichment. Alginate is a biocompatible polysaccharide with poor cell adhesion, whereas polycaprolactone (PCL) is relative cell adhesive. These two materials were coelectrospun as composite scaffolds. Cells collected from alginate and composite fibers demonstrated high stemness, epithelial-mesenchymal transition, invasion, drug resistance, and angiogenesis. Interestingly, cells collected from composite fibers with low ratio of PCL were significantly improved their CSC properties compared to those from pure alginate fibers because few PCL fibers spatially separated cell populations to concentrate CSCs. These results suggested that alginate fibers effectively enriched CSCs and composite fibers created an uneven microenvironment to regulate cell morphology and distribution, by which cell-cell interaction was thus manipulated. These tunable scaffolds are potential to isolate CSCs from different tissues to facilitate the cancer research., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Alginate and polycaprolactone (PCL) were coelectrospun using a dual-jet system to prepare composite nanofibers in defined ratios, and hence both chemical properties and hydrophobicity of scaffolds can be manipulated. These nanofibers were applied in gene immobilization: positively charged polyethyleneimine (PEI)/DNA polyplexes were adsorbed onto anionic alginate fibers, and the higher ratios of alginate resulted in the more immobilized nonviral vectors. Through the incorporation of PCL, biocompatibility of scaffolds was highly improved. Finally, these scaffolds were used for in situ transfection application. Compared to pure alginate fibers, composite fibers not only successfully transferred target genes to adhered cells but also enhanced cell morphology and viability, suggesting that alginate/PCL nanofibers were multifunctional with gene delivery capability and biocompatibility, and the manipulation of their composition can balance and optimize both requirements. To our knowledge, this approach might be the first one using electrostatic interactions to immobilize genes onto nanofibrous scaffolds for in situ transfection application., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Alginate has been previously utilized as an adjuvant in nanoparticle-mediated gene delivery. In this study, we investigated the extent to which alginate promotes in situ transfection from polyelectrolyte multilayers (PEMs). After spiking free alginate molecules, DNA release from PEMs was increased and transgene expression was enhanced, suggesting that alginate may compete with DNA to weaken electrostatic interaction within PEMs. Consequently, alginate was applied to compose multilayers with DNA and polyethyleneimine (PEI). Interestingly, the incorporated alginate increased not only deposition but also delivery of DNA from PEMs. Quartz crystal microbalance (QCM) analysis suggested that the deposited alginate enhanced PEI adsorption which in turn augmented subsequent DNA deposition. In situ transfection experiments revealed that alginate within PEMs improved not only the level but also the duration of transgene expression. This system should be a potential strategy to regulate gene delivery from scaffolds for tissue engineering application., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

To sustain transgene expression, chitosan was studied to immobilize DNA using layer-by-layer assembly to form polyelectrolyte multilayers (PEMs). Higher DNA concentrations and longer deposition periods demonstrated more DNA adsorptions to PEMs. By adjusting pH and the molecular weight of chitosan, PEM structures were manipulated. Chitosan molecules adsorption to PEMs increased when they were at pH 6 because of their low protonation. Furthermore, the configuration of chitosan favored a coiled-form when the pH was high, as the intramolecular repulsion decreased. Therefore, interdiffusion of polyelectrolytes in PEMs was promoted to increase DNA adsorption, especially for chitosan with high molecular weight. For the release experiments, because PEMs fabricated by lower pH chitosan owned less chitosan molecules, DNA release was enhanced. However, this phenomenon did not happen to chitosan with high molecular weight, which should be due to the entanglement between polymer chains. This comprehensive approach should be beneficial to substrate-mediated gene delivery applications., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Chitosan and alginate are two frequently used biomaterials for tissue engineering. In this study, electrospinning technique was applied for their nanofiber fabrications to mimic extracellular environment (ECM). Polyethylene oxide (PEO) was applied to increase viscosities of polymer solutions to obtain nanofibers with appropriate morphologies. To modulate surface properties, a dual jet system was developed to coelectrospin chitosan and alginate nanofibers on one substrate. Because the deposition rates of electrospun fibers linearly correlated to the perfusion rates of polymer solutions, the composition ratios of nanofibers were thus manipulated, which determined both the chemical properties and hydrophobicity of fibrous mats. In vitro cell culture results suggested that the cell morphology highly depended on the fiber composition, and the composite nanofibers demonstrated higher biocompatibility than that on pure fibers. Finally, the degradation of alginate fibers was controlled by the crosslinking process. Reducing calcium ions resulted in partial fiber degradation, by which the composition ratios of nanofibers varied with time. This dynamically changed environment performed a promising property to improve viability of surface cells. Through this tunable system, surface properties of scaffolds can be finely adjusted to benefit tissue engineering applications., (Copyright © 2013 Elsevier Ltd. All rights reserved.)