In situ light-activated materials for skin wound healing and repair: A narrative review.

Dermal wounds are a major global health burden made worse by common comorbidities such as diabetes and infection. Appropriate wound closure relies on a highly coordinated series of cellular events, ultimately bridging tissue gaps and regenerating normal physiological structures. Wound dressings are an important component of wound care management, providing a barrier against external insults while preserving the active reparative processes underway within the wound bed. The development of wound dressings with biomaterial constituents has become an attractive design strategy due to the varied functions intrinsic in biological polymers, such as cell instructiveness, growth factor binding, antimicrobial properties, and tissue integration. Using photosensitive agents to generate crosslinked or photopolymerized dressings in situ provides an opportunity to develop dressings rapidly within the wound bed, facilitating robust adhesion to the wound bed for greater barrier protection and adaptation to irregular wound shapes. Despite the popularity of this fabrication approach, relatively few experimental wound dressings have undergone preclinical translation into animal models, limiting the overall integrity of assessing their potential as effective wound dressings. Here, we provide an up-to-date narrative review of reported photoinitiator- and wavelength-guided design strategies for in situ light activation of biomaterial dressings that have been evaluated in preclinical wound healing models.

Alpha-ketoglutaric acid based polymeric particles for cutaneous wound healing.

Metabolites are not only involved in energy pathways but can also act as signaling molecules. Herein, we demonstrate that polyesters of alpha-ketoglutararte (paKG) can be generated by reacting aKG with aliphatic diols of different lengths, which release aKG in a sustained manner. paKG polymer-based microparticles generated via emulsion-evaporation technique lead to faster keratinocyte wound closures in a scratch assay test. Moreover, paKG microparticles also led to faster wound healing responses in an excisional wound model in live mice. Overall, this study shows that paKG MPs that release aKG in a sustained manner can be used to develop regenerative therapeutic responses.

Effect of Methylation of the Hydrophilic Domain of Tocopheryl Ammonium-Based Lipids on their Nucleic Acid Delivery Properties.

Lipid-enabled nucleic acid delivery has garnered tremendous attention in recent times. Tocopherol among the cationic lipids, 3b-[N-(N',N'-dimethylamino-ethane)carbamoyl]-cholesterol hydrochloride (DC-Chol) with a headgroup of dimethylammonium, and cholesterol as a hydrophobic moiety are found to be some of the most successful lipids and are being used in clinical trials. However, limited efficacy is a major limitation for their broader therapeutic application. In our prior studies, we demonstrated tocopherol to be a potential alternative hydrophobic moiety having additional antioxidant properties to develop efficient and safer liposomal formulations. Inspired by DC-Chol applications and taking cues from our own prior findings, herein, we report the design and synthesis of four alpha-tocopherol-based cationic derivatives with varying degrees of methylation, AC-Toc (no methylation), MC-Toc (monomethylation derivative), DC-Toc (dimethylation derivative), and TC-Toc (trimethylation derivative) and the evaluation of their gene delivery properties. The transfection studies showed that AC-Toc liposomes exhibited superior transfection compared to MC-Toc, DC-Toc, TC-Toc, and control DC-Chol, indicating that methylation in the hydrophilic moiety of Toc-lipids reduced their transfection properties. Cellular internalization studies in the presence of different endocytosis blockers revealed that all four tocopherol lipids were internalized through clathrin-mediated endocytosis, whereas control DC-Chol was found to be internalized through both macropinocytosis and clathrin-mediated endocytosis. These novel Toc-lipids exhibited higher antioxidant properties than DC-Chol by generating less reactive oxygen species, indicating lower cytotoxicity. Our present findings suggest that AC-Toc may be considered as an alternative to DC-Chol in liposomal transfections.

α-Tocopherol-anchored gemini lipids with delocalizable cationic head groups: the effect of spacer length on DNA compaction and transfection properties.

Understanding the role of structural units in cationic lipids used for gene delivery is essential in designing efficient gene delivery vehicles. Herein, we report a systematic structure-activity investigation on the influence of the spacer length on the DNA compaction ability and the transfection properties of gemini lipids with delocalizable cationic head groups. We have synthesized a series of dimeric cationic lipids varying in spacer length. The DNA binding interactions of liposomal formulations were characterized by gel electrophoresis and ethidium bromide (EtBr) exclusion assays. Condensation potentials were optimized and the best results were observed with cationic lipids possessing a 6 methylene spacer (TIM 6). We found that the size of the lipid/DNA complex decreased with the increase in spacer chain length up to a 6 methylene spacer TIM 6 and increased further. We have optimized the dimeric lipid/DOPE molar formulation using the ß-galactosidase activity assay and found that the molar ratio of 1 : 1.5 (gemini lipid/DOPE) showed the maximum transfection among all molar ratios. The cellular uptake and co-localization of lipoplexes were observed by cell analysis and imaging using confocal microscopy. The results confirm that the lipoplex derived from lipid TIM 6 and pCMV-bgal/DNA internalizes via cellular endocytosis. The cytotoxicity studies using the MTT assay revealed that all formulations show comparable cell viability to the commercial standard even at higher charge ratios. Overall, the data suggest that the DNA compaction ability of these lipid dimers depends on the spacer chain length and the gemini lipid containing a six methylene aliphatic spacer has the maximum potential to deliver genes.

Evolution of New "Bolaliposomes" using Novel α-Tocopheryl Succinate Based Cationic Lipid and 1,12-Disubstituted Dodecane-Based Bolaamphiphile for Efficient Gene Delivery.

Nonviral lipid-based vectors are promising transporting systems for the intracellular delivery of therapeutic gene sequences and directly influence the success of gene delivery. However, the associated drawbacks like lower transfection, toxicity, and targetability require further improvement. Thus, herein, we report a novel lipid formulation by the mixing of two distinct cationic surfactants such as tocopheryl succinate based cationic lipid and 1,12 dodecane based bolaamphiphile and prove it to be a good transfection reagent with its competing potential with the "golden standard", Lipofectamine 3000 (L3K). These interesting aggregations were named "Bolaliposome" and showed adequate unilamellar vesicle morphology under transmission electron microscopy, having a size of around 100 nm and could transfect efficiently different varieties of cell lines. Moreover, the generated complexes from bolaliposome and DNA (bolalipoplex) were characterized in terms of surface potential, hydrodynamic size, and gel electrophoresis. Various pharmacological inhibitors were also used in reporter gene expression to prove that the complexes followed the clathrin-mediated endocytosis. Finally, these findings would be helpful in the making of new aggregates and the development of better cytofectins. This was developed by optimizing the formulation based on the efficiency of reporter gene expression performed using the pEGFP-N3 plasmid.

Novel 1,2,3-triazolium-based dicationic amphiphiles synthesized using click-chemistry approach for efficient plasmid delivery.

Herein, we report the synthesis, characterization and evaluation of the transfection efficiencies of a series of dicationic amphiphiles designed to construct quaternary ammonium ion-based cationic lipids varying in chain length of the hydrophobic back bone connected individually through head group to a 1,2,3-triazolium cation consisting of 2-hydroxy ethyl chain as substitution. Accordingly, three dicationic amphiphiles were synthesized by "click chemistry" approach and formulated to bilayered vesicles using DOPE as a co-lipid. The transfection efficacies of these novel lipid formulations were measured and correlated with the results obtained from various physicochemical techniques. Importantly, the observed gradient in the activity profile, where the transfection potential increased with decreasing chain length of the lipid hydrophobic back bone, highlights the synergistic interplay of the lipid alkyl chain length in coordination with charge delocalization in modulating the transfection potency of these 1,2,3-triazolium-based lipids.

Effects of heterocyclic-based head group modifications on the structure-activity relationship of tocopherol-based lipids for non-viral gene delivery.

Gene therapy, a promising strategy for the delivery of therapeutic nucleic acids, is greatly dependent on the development of efficient vectors. In this study, we designed and synthesized several tocopherol-based lipids varying in the head group region. Here, we present the structure-activity relationship of stable aqueous suspensions of lipids that were synthetically prepared and formulated with 1,2-dioleoyl phosphatidyl ethanolamine (DOPE) as the co-lipid. The physicochemical properties such as the hydrodynamic size, zeta potential, stability and morphology of these formulations were investigated. Interaction with plasmid DNA was clearly demonstrated through gel binding and EtBr displacement assays. Further, the transfection potential was examined in mouse neuroblastoma Neuro-2a, hepatocarcinoma HepG2, human embryonic kidney and Chinese hamster ovarian cell lines, all of different origins. Cell-uptake assays with N-methylpiperidinium, N-methylmorpholinium, N-methylimidazolium and N,N-dimethylaminopyridinium head group containing formulations evidently depicted efficient cell uptake as observed by particulate cytoplasmic fluorescence. Trafficking of lipoplexes using an endocytic marker and rhodamine-labeled phospholipid DHPE indicated that the lipoplexes were not sequestered in the lysosomes. Importantly, lipoplexes were non-toxic and mediated good transfection efficiency as analyzed by ß-Gal and GFP reporter gene expression assays which established the superior activity of lipids whose structures correlate strongly with the transfection efficiency.