Photo-irradiation paradigm: Mapping a remarkable facile technique used for advanced drug, gene and cell delivery

Overview of Tissue Engineering and Drug Delivery Applications of Reactive Electrospinning and Crosslinking Techniques of Polymeric Nanofibers with Highlights on Their Biocompatibility Testing and Regulatory Aspects

Traditional electrospinning is a promising technique for fabricating nanofibers for tissue engineering and drug delivery applications. The method is highly efficient in producing nanofibers with morphology and porosity similar to the extracellular matrix. Nonetheless, and in many instances, the process has faced several limitations, including weak mechanical strength, large diameter distributions, and scaling-up difficulties of its fabricated electrospun nanofibers. The constraints of the polymer solution's intrinsic properties are primarily responsible for these limitations. Reactive electrospinning constitutes a novel and modified electrospinning techniques developed to overcome those challenges and improve the properties of the fabricated fibers intended for various biomedical applications. This review mainly addresses reactive electrospinning techniques, a relatively new approach for making in situ or post-crosslinked nanofibers. It provides an overview of and discusses the recent literature about chemical and photoreactive electrospinning, their various techniques, their biomedical applications, and FDA regulatory aspects related to their approval and marketing. Another aspect highlighted in this review is the use of crosslinking and reactive electrospinning techniques to enhance the fabricated nanofibers' physicochemical and mechanical properties and make them more biocompatible and tailored for advanced intelligent drug delivery and tissue engineering applications.

Recent Advances in Stimuli-Responsive Doxorubicin Delivery Systems for Liver Cancer Therapy

Doxorubicin (DOX) is one of the most commonly used drugs in liver cancer. Unfortunately, the traditional chemotherapy with DOX presents many limitations, such as a systematic release of DOX, affecting both tumor tissue and healthy tissue, leading to the apparition of many side effects, multidrug resistance (MDR), and poor water solubility. Furthermore, drug delivery systems' responsiveness has been intensively studied according to the influence of different internal and external stimuli on the efficiency of therapeutic drugs. In this review, we discuss both internal stimuli-responsive drug-delivery systems, such as redox, pH and temperature variation, and external stimuli-responsive drug-delivery systems, such as the application of magnetic, photo-thermal, and electrical stimuli, for the controlled release of Doxorubicin in liver cancer therapy, along with the future perspectives of these smart delivery systems in liver cancer therapy.

Near-infrared photoresponsive drug delivery nanosystems for cancer photo-chemotherapy

Drug delivery systems (DDSs) based on nanomaterials have shown a promise for cancer chemotherapy; however, it remains a great challenge to localize on-demand release of anticancer drugs in tumor tissues to improve therapeutic effects and minimize the side effects. In this regard, photoresponsive DDSs that employ light as an external stimulus can offer a precise spatiotemporal control of drug release at desired sites of interest. Most photoresponsive DDSs are only responsive to ultraviolet-visible light that shows phototoxicity and/or shallow tissue penetration depth, and thereby their applications are greatly restricted. To address these issues, near-infrared (NIR) photoresponsive DDSs have been developed. In this review, the development of NIR photoresponsive DDSs in last several years for cancer photo-chemotherapy are summarized. They can achieve on-demand release of drugs into tumors of living animals through photothermal, photodynamic, and photoconversion mechanisms, affording obviously amplified therapeutic effects in synergy with phototherapy. Finally, the existing challenges and further perspectives on the development of NIR photoresponsive DDSs and their clinical translation are discussed.

Photo-crosslinked anhydride-modified polyester and -ethers for pH-sensitive drug release

Photo-crosslinkable polymers have a great potential for the delivery of sensitive drugs. They allow preparation of drug releasing devices by photo-crosslinking, thus avoiding high processing temperatures. In this study, the hydrolysis behavior and drug release of three different photo-crosslinkable poly(ether anhydride)s and one poly(ester anhydride) were investigated. Three-arm poly(ethylene glycol) or polycaprolactone was reacted with succinic anhydride to obtain carboxylated macromers, and further functionalized with methacrylic anhydride to form methacrylated marcromers with anhydride linkages. The synthetized macromers were used to prepare photo-crosslinked matrices with different hydrolytic degradation times for active agent release purposes. The hydrolysis was clearly pH-sensitive: polymer networks degraded slowly in acidic conditions, and degradation rate increased as the pH shifted towards basic conditions. Drug release was studied with two water-soluble model drugs lidocaine (234 mol/g) and vitamin B₁₂ (1355 g/mol). Vitamin B₁₂ was released mainly due to polymer network degradation, whereas smaller molecule lidocaine was released also through diffusion and swelling of polymer network. Only a small amount of vitamin B₁₂ was released in acidic conditions (pH 1.3 and pH 2.1). These polymers have potential in colon targeted drug delivery as the polymer could protect sensitive drugs from acidic conditions in the stomach, and the drug would be released as the conditions change closer to neutral pH in the intestine.

Guiding protein delivery into live cells using DNA-programmed membrane fusion

Intracellular delivery of proteins provides a direct means to manipulate cell function and probe the intracellular environment. However, direct cytoplasmic delivery of proteins suffers from limited availability of efficient toolsets, and thus remains challenging in research and therapeutic applications. Natural biological cargo delivery processes, like SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex mediated membrane fusion and other vesicle fusion in live cells, enable targeted delivery with high efficiency. A surrogate of SNARE machinery represents a new direction in intracellular protein delivery. Here, we report a DNA-programmed membrane fusion strategy for guiding the efficient intracellular delivery of proteins into live cells. The inherent programmability of DNA hybridization provides spatiotemporal control of the fusion between protein-encapsulated liposomes and cell membranes, enabling rapid release of proteins directly into the cytoplasm, while still remaining functional due to the bypassing of the endosomal trap. We further demonstrate that delivered exogenous Cytochrome c effectively regulates the cell fate. Hence, this DNA-mediated fusion strategy holds great potential for protein drug delivery, regenerative medicine and gene editing.

IONP-doped nanoparticles for highly effective NIR-controlled drug release and combination tumor therapy

Despite advances in controlled drug delivery, drug delivery systems (DDSs) with controlled activated drug release and high spatial and temporal resolution are still required. Theranostic nanomedicine is capable of diagnosis, therapy, and monitoring the delivery and distribution of drug molecules and has received growing interest. In this study, a near-infrared light-controlled “off–on” DDS with magnetic resonance imaging and magnetic targeting properties was developed using a hybrid nanoplatform (carbon nanotubes [CNTs]-iron oxide nanoparticle). Doxorubicin (DOX) and distearoyl-sn-glycero-3-phosphoethanolamine-PEG were adsorbed onto CNTs-iron oxide nanoparticle, and then to avoid the unexpected drug release during circulation, 1-myristyl alcohol was used to encapsulate the CNTs–drug complex. Herein, multifunctional DOX-loaded nanoparticles (NPs) with “off–on” state were developed. DOX-NPs showed an obvious “off–on” effect (temperature increase, drug release) controlled by near-infrared light in vitro and in vivo. In the in vivo and in vitro studies, DOX-NPs exhibited excellent magnetic resonance imaging ability, magnetic targeting property, high biosafety, and high antitumor combined therapeutic efficacy (hyperthermia combined with chemotherapy). These results highlight the great potential of DOX-NPs in the treatment of cancer.

Enzyme-instructed self-assembly with photo-responses for the photo-regulation of cancer cells

Enzyme-instructed self-assembly was regulated by photo-irradiation to turn on the fluorescence as well as to induce a disassembly process.

Simultaneously Photo-Cleavable and Activatable Prodrug-Backboned Block Copolymer Micelles for Precise Anticancer Drug Delivery

A simultaneously photo-cleavable and activatable prodrug-backboned block copolymer (BCP) micelle strategy is demonstrated. Without light treatment, the micelles stay silent and inactivated, being biocompatible to normal tissues. Concurrent chain cleavage of BCP micelles and the activation of Pt(IV) prodrug could be temporally and spatially triggered by UV or even visible light for precise anticancer drug delivery.

Biodegradable star-shaped polycyclic ester elastomers: Preparation, degradability, protein release, and biocompatibility in vitro

Effective local delivery methods for sustained and stable release of protein drugs are urgently needed. Biodegradable elastomers based on star-shaped polycyclic esters have received attention for their drug-loading and drug-release kinetics. However, the long degradation periods resulting from their strong lipophilicity greatly hinder their application. In this study, we synthesized new cross-linked elastomers based on methyl-acrylic-star-poly(ϵ-caprolactone- co-d,l-lactide) cyclic ester and methyl-bi-acrylic-poly(ϵ-caprolactone-b-poly(ethylene glycol)-b-ϵ-caprolactone) with different molecular weights; determined their physical, thermal, and morphological characteristics; and studied their in vitro degradation and release of bovine serum albumin and recombinant human interleukin 2. Elastomer hydrophilicity improved with the introduction of methyl-bi-acrylic-poly(ϵ-caprolactone-b-poly(ethylene glycol)-b-ϵ-caprolactone), and a shorter degradation period (~25 weeks) was achieved. Additionally, the degradation rate could be adjusted by varying the composition of methyl-bi-acrylic-poly(ϵ-caprolactone-b-poly(ethylene glycol)-b-ϵ-caprolactone) to directly influence the degree of swelling, cross-linking density, and sol content of the elastomer. The controlled rate of bovine serum albumin and recombinant human interleukin 2 release increased with a larger degree of swelling, higher sol content, and lower cross-link density of the elastomers. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analysis showed good biocompatibility. These results suggest that these new elastomers are potential candidates for carrier materials in controlled, implantable delivery systems for protein drugs and other biomedical applications.

Synthesis of Photo- and pH Dual-Sensitive Amphiphilic Copolymer PEG43-b-P(AA76-co-NBA35-co-tBA9) and Its Micellization as Leakage-Free Drug Delivery System for UV-Triggered Intracellular Delivery of Doxorubicin

Novel photo- and pH dual-sensitive amphiphilic copolymers containing photolabile o-nitrobenzyl (NB) groups were designed via combination of ATRP, hydrolyzation, and simple esterification reaction and self-assembled into stimuli-regulated amphiphilic micelles in aqueous solution. On the basis of the optimization of the morphology and particle size of the micelles via modulating the number of the photocleavable o-nitrobenzyl acrylate (NBA) units, the unique ones assembled from PEG43-b-P(AA76-co-NBA35-co-tBA9) with an average hydrodynamic diameter (Dh) of 163 nm was selected as a potential drug delivery system (DDS) for UV-triggered delivery of doxorubicin (DOX). The micelles possessed a favorable drug-loading capacity (DLC) of 27.5%, with the hydrodynamic diameter of 213 nm after DOX-loading. Most importantly, the DOX-loaded PEG43-b-P(AA76-co-NBA35-co-tBA9) micelles exhibited a cumulative DOX release ratio of only 3.69% in the simulated physiological medium within 6 days without UV-irradiation, indicating their potential as leakage-free DDS. As in the acidic media mimicking the tumor microenvironment, a high cumulative DOX release ratio of 74.70% was achieved within 6 days after UV-irradiation for 20 min, showing a sustained release behavior. Under UV-irradiation, the photolabile o-nitrobenzyl moieties were cleaved off, the amphiphilic copolymer transformed into a water-soluble polymer, favoring the metabolism of drug carriers, and the micelles were demicellized to accelerate the drug release in a triggered or on-demand manner.

Redox Reducible and Hydrolytically Degradable PEG-PLA Elastomers as Biomaterial for Temporary Drug-Eluting Medical Devices

With the aim to develop biomaterials for temporary medical devices, a series of novel reducible and/or degradable elastomers has been prepared from PLA-b-PEG-b-PLA copolymers photo-crosslinked with diallyl sulfide or pentaerythritol tetrakis(3-mercaptopropionate). Thermal and mechanical properties, including elastic limit and Young modulus, are assessed. Degradation is then evaluated under standard hydrolytic conditions. Reducibility of a selected elastomer is then illustrated using 2-mercaptoethanol or glutathione as reducing agents. The redox-sensitivity of the selected elastomer and the possibility to modulate the degradability are shown. Considering drug-eluting elastomeric devices applications, anti-inflammatory drug ibuprofen loading is illustrated with the two simplest elastomer formulations. A rapid or slow linear release is observed as a function of the low or high molecular weight of the triblock pre-polymers. Finally, the cytocompatibility of the degradable elastomers is assessed with regard to their potential to favor or inhibit L929 murine fibroblasts proliferation as a function of the hydrophilicity/hydrophobicity of the triblock copolymers.