Electrically controlled release of 5-fluorouracil from conductive gelatin methacryloyl-based hydrogels

Preparation, Characterization, and Antiangiogenic Evaluation of a Novel 5-Fluorouracil Derivative Solid Lipid Nanoparticle with a Hen's Egg Chorioallantoic Membrane Assay and Wound Healing Response in HaCaT Keratinocytes

5-Fluorouracil is a heterocyclic aromatic organic compound, and it is commonly used as a chemotherapeutic agent in many cancers. The present goal is to analyze and characterize the physicochemical and biological properties of a new therapeutic formulation of 5-FUD-Gal under simulated chronic wound and oxidative stress conditions. After synthesis of a new 5-fluorouracil derivative, preparation and characterization of the formulation were carried out. The antiangiogenic effect, wound healing, and oxidative stress responses were conducted with a HET-CAM assay and in vitro cell culture technique. The results initially demonstrated that 5-FUD-Gal synthesized by a series of reactions and the SLN formulation were prepared successfully. A strong cell protective effect above 98% cell viability was detected at 20 μM at 48 h. The wound closure of the HaCaT scratch assay was calculated to be 90.12 and 98.98% at 10 and 20 μM concentrations, respectively, at 48 h. Moreover, the strongest effect of 5-FUD-Gal-F was observed at 20 μM concentration on chicken embryos. This study provides novel insights that a new derivative of semisynthetic 5-FUD-Gal-F can be further evaluated as a therapeutic chemical compound in cancer disease.

GelMA/PEDOT:PSS Composite Conductive Hydrogel-Based Generation and Protection of Cochlear Hair Cells through Multiple Signaling Pathways

Recent advances in cochlear implantology are exemplified by novel functional strategies such as bimodal electroacoustic stimulation, in which the patient has intact low-frequency hearing and profound high-frequency hearing pre-operatively. Therefore, the synergistic restoration of dysfunctional cochlear hair cells and the protection of hair cells from ototoxic insults have become a persistent target pursued for this hybrid system. In this study, we developed a composite GelMA/PEDOT:PSS conductive hydrogel that is suitable as a coating for the cochlear implant electrode for the potential local delivery of otoregenerative and otoprotective drugs. Various material characterization methods (e.g., 1H NMR spectroscopy, FT-IR, EIS, and SEM), experimental models (e.g., murine cochlear organoid and aminoglycoside-induced ototoxic HEI-OC1 cellular model), and biological analyses (e.g., confocal laser scanning microscopy, real time qPCR, flow cytometry, and bioinformatic sequencing) were used. The results demonstrated decent material properties of the hydrogel, such as mechanical (e.g., high tensile stress and Young's modulus), electrochemical (e.g., low impedance and high conductivity), biocompatibility (e.g., satisfactory cochlear cell interaction and free of systemic toxicity), and biosafety (e.g., minimal hemolysis and cell death) features. In addition, the CDR medicinal cocktail sustainably released by the hydrogel not only promoted the expansion of the cochlear stem cells but also boosted the trans-differentiation from cochlear supporting cells into hair cells. Furthermore, hydrogel-based drug delivery protected the hair cells from oxidative stress and various forms of programmed cell death (e.g., apoptosis and ferroptosis). Finally, using large-scale sequencing, we enriched a complex network of signaling pathways that are potentially downstream to various metabolic processes and abundant metabolites. In conclusion, we present a conductive hydrogel-based local delivery of bifunctional drug cocktails, thereby serving as a potential solution to intracochlear therapy of bimodal auditory rehabilitation and diseases beyond.

Gelatin microsphere-alginate hydrogel combined system for sustained and gastric targeted delivery of 5-fluorouracil

In the current study, novel gelatin microspheres/methacrylated alginate hydrogel combined system (5-FU-GELms/Alg-MA) was developed for gastric targeted delivery of 5-fluorouracil as an anticancer agent. While water-in-oil emulsification method was used for the production of 5-FU-GELms, Alg-MA was synthesized through methacrylation reaction occurred by epoxide ring-opening mechanism. Then, 5-FU-GELms/Alg-MA hydrogel system was fabricated by the encapsulation of 5-FU-GELms into Alg-MA hydrogel network via UV-crosslinking. To evaluate applicability of fabricated 5-FU-GELms/Alg-MA as gastric targeted drug delivery vehicle, both swelling and in vitro drug release experiments were carried out at pH 1.2 medium resembling gastric fluid. Compared to drug release directly from 5-FU-GELms, 5-FU-GELms/Alg-MA hydrogel system showed more controlled and sustained drug release profile with lower amount of cumulative release starting from early stages, since hydrogel matrix created a barrier to the diffusion of 5-FU included in microspheres. Drug release kinetic results obtained by applying various kinetic models to release data showed that the mechanism of 5-FU release from 5-FU-GELms/Alg-MA hydrogel system is controlled by Fickian diffusion. All results revealed that 5-FU-GELms/Alg-MA hydrogel integrated system could be potentially utilized as gastric targeted drug carrier to enhance therapeutic efficacy and reduce systemic side effects in gastric cancer treatments for future studies.

Microsponge-Based Gel Loaded with Immunosuppressant as a Simple and Valuable Strategy for Psoriasis Therapy: Determination of Pro-Inflammatory Response through Cytokine IL-2 mRNA Expression

Tacrolimus (TL) is a topical calcineurin inhibitor immunosuppressive drug widely used to manage various skin disorders. Herein, we report a TL-loaded microsphere gel formulation with severe atopic dermatitis effects that are required to manage skin disorders. The current study adopted a modified emulsion solvent evaporation technique to synthesize TL-loaded microspheres, which were further converted into gels for skin use. Characterization of the synthesized formulation was performed by differential dynamic light scattering, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray crystallography, Brunauer-Emmett-Teller (BET) analysis, differential scanning calorimetry, and drug release. A Franz diffusion cell was used to study the diffusion of TL for up to 8 h at pH 6.8 and 5.5. Evaluation of cell viability was determined by MTT assay and showed higher IC50 values compared to the plain drug. RNA extraction, real-time polymerase chain reaction (RT-PCR), and reverse transcription were also performed to determine the expression levels of the anti-inflammatory cytokine IL-2. Particle size determination was performed by a zeta sizer, and the TL microsphere size was 1745 ± 70 nm with a good polydispersity (0.337 ± 0.12). The drug entrapment efficiency was also very good at 60% ± 10, and the drug release was 93.9% ± 3.5 within 8 h. An in vitro diffusion study of the formulation also showed improved permeability at both pH values (4.5 and 5.5). The findings of the hemolytic tests demonstrated that TL-MG at concentrations of 50, 100, and 200 mg/mL did not produce any hemolysis. A dose-dependent pattern of cytotoxicity was found during the cell viability assay, with an IC50 value of 787.55 ± 12.78 µg/mL. There was a significant decrease in the IL-2 level in the TL-MG group compared to the other groups. TL-MG microspheres were nontoxic carriers for tacrolimus delivery, with greater loading capacity, a significant release profile, and enhanced cellular uptake with improved permeability.

Electro-Responsive Conductive Blended Hydrogel Patch

The proposed electro-responsive hydrogel has great benefit for transdermal drug delivery system (TDDS) applications. To improve the physical or chemical properties of hydrogels, a number of researchers have previously studied the mixing efficiencies of the blended hydrogels. However, few studies have focused on improving the electrical conductivity and drug delivery of the hydrogels. We developed a conductive blended hydrogel by mixing alginate with gelatin methacrylate (GelMA) and silver nanowire (AgNW). We demonstrated that and the tensile strength of blended hydrogels were increased by a factor of 1.8 by blending GelMA and the electrical conductivity was enhanced by a factor of 18 by the addition of AgNW. Furthermore, the GelMA-alginate-AgNW (Gel-Alg-AgNW) blended hydrogel patch enabled on-off controllable drug release, indicating 57% doxorubicin release in response to electrical stimulation (ES) application. Therefore, this electro-responsive blended hydrogel patch could be useful for smart drug delivery applications.

Gel Formulations for Topical Treatment of Skin Cancer: A Review

Skin cancer, with all its variations, is the most common type of cancer worldwide. Chemotherapy by topical application is an attractive strategy because of the ease of application and non-invasiveness. At the same time, the delivery of antineoplastic agents through the skin is difficult because of their challenging physicochemical properties (solubility, ionization, molecular weight, melting point) and the barrier function of the stratum corneum. Various approaches have been applied in order to improve drug penetration, retention, and efficacy. This systematic review aims at identifying the most commonly used techniques for topical drug delivery by means of gel-based topical formulations in skin cancer treatment. The excipients used, the preparation approaches, and the methods characterizing gels are discussed in brief. The safety aspects are also highlighted. The combinatorial formulation of nanocarrier-loaded gels is also reviewed from the perspective of improving drug delivery characteristics. Some limitations and drawbacks in the identified strategies are also outlined and considered within the future scope of topical chemotherapy.

The State of the Art of Natural Polymer Functionalized Fe3O4 Magnetic Nanoparticle Composites for Drug Delivery Applications: A Review

Natural polymers have received a great deal of interest for their potential use in the encapsulation and transportation of pharmaceuticals and other bioactive compounds for disease treatment. In this perspective, the drug delivery systems (DDS) constructed by representative natural polymers from animals (gelatin and hyaluronic acid), plants (pectin and starch), and microbes (Xanthan gum and Dextran) are provided. In order to enhance the efficiency of polymers in DDS by delivering the medicine to the right location, reducing the medication's adverse effects on neighboring organs or tissues, and controlling the medication's release to stop the cycle of over- and under-dosing, the incorporation of Fe3O4 magnetic nanoparticles with the polymers has engaged the most consideration due to their rare characteristics, such as easy separation, superparamagnetism, and high surface area. This review is designed to report the recent progress of natural polymeric Fe3O4 magnetic nanoparticles in drug delivery applications, based on different polymers' origins.

Gelatin-based anticancer drug delivery nanosystems: A mini review

Drug delivery nanosystems (DDnS) is widely developed recently. Gelatin is a high-potential biomaterial originated from natural resources for anticancer DDnS, which can effectively improve the utilization of anticancer drugs and reduce side effects. The hydrophilic, amphoteric behavior and sol-gel transition of gelatin can be used to fulfill various requirements of anticancer DDnS. Additionally, the high number of multifunctional groups on the surface of gelatin provides the possibility of crosslinking and further modifications. In this review, we focus on the properties of gelatin and briefly elaborate the correlation between the properties and anticancer DDnS. Furthermore, we discuss the applications of gelatin-based DDnS in various cancer treatments. Overall, we have summarized the excellent properties of gelatin and correlated with DDnS to provide a manual for the design of gelatin-based materials for DDnS.

Preparation, properties, and applications of gelatin-based hydrogels (GHs) in the environmental, technological, and biomedical sectors

Gelatin's versatile functionalization offers prospects of facile and effective crosslinking as well as combining with other materials (e.g., metal nanoparticles, carbonaceous, minerals, and polymeric materials exhibiting desired functional properties) to form hybrid materials of improved thermo-mechanical, physio-chemical and biological characteristics. Gelatin-based hydrogels (GHs) and (nano)composite hydrogels possess unique functional features that make them appropriate for a wide range of environmental, technical, and biomedical applications. The properties of GHs could be balanced by optimizing the hydrogel design. The current review explores the various crosslinking techniques of GHs, their properties, composite types, and ultimately their end-use applications. GH's ability to absorb a large volume of water within the gel network via hydrogen bonding is frequently used for water retention (e.g., agricultural additives), and absorbency towards targeted chemicals from the environment (e.g., as wound dressings for absorbing exudates and in water treatment for absorbing pollutants). GH's controllable porosity makes its way to be used to restrict access to chemicals entrapped within the gel phase (e.g., cell encapsulation), regulate the release of encapsulated cargoes within the GH (e.g., drug delivery, agrochemicals release). GH's soft mechanics closely resembling biological tissues, make its use in tissue engineering to deliver suitable mechanical signals to neighboring cells. This review discussed the GHs as potential materials for the creation of biosensors, drug delivery systems, antimicrobials, modified electrodes, water adsorbents, fertilizers and packaging systems, among many others. The future research outlooks are also highlighted.

Electroconductive and injectable hydrogels based on gelatin and PEDOT:PSS for mini-invasive approaches in nervous tissue regeneration

This work describes the development of electroconductive hydrogels as injectable matrices for neural tissue regeneration by exploiting a biocompatible conductive polymer – i.e. poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) – combined with a biomimetic...

An interpenetrating and patternable conducting polymer hydrogel for electrically stimulated release of glutamate

Recent advances in drug delivery have made it possible to release bioactive agents from neural implants specifically to local tissues. Conducting polymer coatings have been explored as a delivery platform in bioelectronics, however, their utility is restricted by their limited loading capacity and stability. This study presents the fabrication of a stable conducting polymer hydrogel (CPH), comprising the hydrogel gelatin methacrylate (GelMA), and conducting polymer polypyrrole (PPy) for the electrically controlled delivery of glutamate (Glu). The hybrid GelMA/PPy/Glu can be photolithographically patterned and covalently bonded to an electrode. Fourier-transform infrared (FTIR) analysis confirmed the interpenetrating nature of PPy through the GelMA hydrogels. Electrochemical polymerisation of PPy/Glu through the GelMA hydrogels resulted in a significant increase in the charge storage capacity as determined by cyclic voltammetry (CV). Long-term electrochemical and mechanical stability was demonstrated over 1000 CV cycles and extracts of the materials were cytocompatible with SH-SY5Y neuroblastoma cell lines. Release of Glu from the CPH was responsive to electrical stimulation with almost five times the amount of Glu released upon constant reduction (-0.6 V) compared to when no stimulus was applied. Notably, GelMA/PPy/Glu was able to deliver almost 14 times higher amounts of Glu compared to conventional PPy/Glu films. The described CPH coatings are well suited in implantable drug delivery applications and compared to conducting polymer films can deliver higher quantities of drug in response to mild electrical stimulus. STATEMENT OF SIGNIFICANCE: Conducting polymer hydrogels (CPH) have been explored for the electrically controlled release of bioactives from implantable devices. Typically, the conducting polymer component does not fully penetrate the hydrogel. We report, for the first time, a completely interpenetrating CPH allowing for the full benefits of the composite material to be realised, the hydrogels provide a reservoir for drug delivery, and conducting polymer renders the material responsive to electrical stimulation for drug release. We report a CPH for the electrically controlled delivery of glutamate (excitatory neurotransmitter) where several-fold more glutamate can be delivered compared to conducting polymer films. The described CPH coatings are well suited for use in bioelectronic devices to deliver large quantities of drug in response to mild electrical stimulus.

Organic Bioelectronics for In Vitro Systems

Bioelectronics have made strides in improving clinical diagnostics and precision medicine. The potential of bioelectronics for bidirectional interfacing with biology through continuous, label-free monitoring on one side and precise control of biological activity on the other has extended their application scope to in vitro systems. The advent of microfluidics and the considerable advances in reliability and complexity of in vitro models promise to eventually significantly reduce or replace animal studies, currently the gold standard in drug discovery and toxicology testing. Bioelectronics are anticipated to play a major role in this transition offering a much needed technology to push forward the drug discovery paradigm. Organic electronic materials, notably conjugated polymers, having demonstrated technological maturity in fields such as solar cells and light emitting diodes given their outstanding characteristics and versatility in processing, are the obvious route forward for bioelectronics due to their biomimetic nature, among other merits. This review highlights the advances in conjugated polymers for interfacing with biological tissue in vitro, aiming ultimately to develop next generation in vitro systems. We showcase in vitro interfacing across multiple length scales, involving biological models of varying complexity, from cell components to complex 3D cell cultures. The state of the art, the possibilities, and the challenges of conjugated polymers toward clinical translation of in vitro systems are also discussed throughout.

Dual stimuli-sensitive carrageenan-based formulation for additive manufacturing

The design and development of controlled release systems of molecules of interest (nutrients, flavors, and drugs) have attracted significant attention over several years. Herein, we report a formulation of dual temperature and electro responsive κ- and ι-carrageenan based hydrogel for efficient food material and drug delivery. The microstructure and the thermal behavior of the hydrogel were characterized. The in-vitro drug release from the hydrogel was also studied. Using this carrageenan-based formulation and folic acid as the drug model, a high drug loading, and a sustained release because of either electric field or temperature were observed. In principle, the proposed formulation does not rely on 3D printing to perform its function; however, it adds to the feedstocks for 3D printing in the food and pharmaceutical industries. For the future, this could allow potentially more complex smart structures to be created from this material, further tuning release behavior.

3D bioprinting of conductive hydrogel for enhanced myogenic differentiation

Recently, hydrogels have gained enormous interest in three-dimensional (3D) bioprinting toward developing functional substitutes for tissue remolding. However, it is highly challenging to transmit electrical signals to cells due to the limited electrical conductivity of the bioprinted hydrogels. Herein, we demonstrate the 3D bioprinting-assisted fabrication of a conductive hydrogel scaffold based on poly-3,4-ethylene dioxythiophene (PEDOT) nanoparticles (NPs) deposited in gelatin methacryloyl (GelMA) for enhanced myogenic differentiation of mouse myoblasts (C2C12 cells). Initially, PEDOT NPs are dispersed in the hydrogel uniformly to enhance the conductive property of the hydrogel scaffold. Notably, the incorporated PEDOT NPs showed minimal influence on the printing ability of GelMA. Then, C2C12 cells are successfully encapsulated within GelMA/PEDOT conductive hydrogels using 3D extrusion bioprinting. Furthermore, the proliferation, migration and differentiation efficacies of C2C12 cells in the highly conductive GelMA/PEDOT composite scaffolds are demonstrated using various in vitro investigations of live/dead staining, F-actin staining, desmin and myogenin immunofluorescence staining. Finally, the effects of electrical signals on the stimulation of the scaffolds are investigated toward the myogenic differentiation of C2C12 cells and the formation of myotubes in vitro. Collectively, our findings demonstrate that the fabrication of the conductive hydrogels provides a feasible approach for the encapsulation of cells and the regeneration of the muscle tissue.

Polymer-Based Smart Drug Delivery Systems for Skin Application and Demonstration of Stimuli-Responsiveness

Progress in recent years in the field of stimuli-responsive polymers, whose properties change depending on the intensity of a signal, permitted an increase in smart drug delivery systems (SDDS). SDDS have attracted the attention of the scientific community because they can help meet two current challenges of the pharmaceutical industry: targeted drug delivery and personalized medicine. Controlled release of the active ingredient can be achieved through various stimuli, among which are temperature, pH, redox potential or even enzymes. SDDS, hitherto explored mainly in oncology, are now developed in the fields of dermatology and cosmetics. They are mostly hydrogels or nanosystems, and the most-used stimuli are pH and temperature. This review offers an overview of polymer-based SDDS developed to trigger the release of active ingredients intended to treat skin conditions or pathologies. The methods used to attest to stimuli-responsiveness in vitro, ex vivo and in vivo are discussed.

Biomedical application of photo-crosslinked gelatin hydrogels

Abstract

During the past decades, photo-crosslinked gelatin hydrogel (methacrylated gelatin, GelMA) has gained a lot of attention due to its remarkable application in the biomedical field. It has been widely used in cell transplantation, cell culture and drug delivery, based on its crosslinking to form hydrogels with tunable mechanical properties and excellent bio-compatibility when exposed to light irradiation to mimic the micro-environment of native extracellular matrix (ECM). Because of its unique biofunctionality and mechanical tenability, it has also been widely applied in the repair and regeneration of bone, heart, cornea, epidermal tissue, cartilage, vascular, peripheral nerve, oral mucosa, and skeletal muscle et al. The purpose of this review is to summarize the recent application of GelMA in drug delivery and tissue engineering field. Moreover, this review article will briefly introduce both the development of GelMA and the characterization of GelMA. Finally, we discuss the challenges and future development prospects of GelMA as a tissue engineering material and drug or gene delivery carrier, hoping to contribute to accelerating the development of GelMA in the biomedical field.

Graphical abstract

Diagnostics of skin features through 3D skin mapping based on electro-controlled deposition of conducting polymers onto metal-sebum modified surfaces and their possible applications in skin treatment

Analytical diagnostics of skin features was developed through application of portable and fast skin mapping based on electro-controlled deposition of conducting polymers onto metal-sebum modified surfaces. In this analytical diagnostic technique, the development of skin pattern is based on electropolymerization of conducting polymers within insulating barriers in skin stamp provided by natural sebum to monitor the 3D nature of various skin features. The recorded skin maps reach a μm-level resolution and are proved to be capable of recognition, enhancement, and reproduction of surface outlines of various skin topographies, subsequently assisting dermatological diagnosis. The technique can precisely record skin surface morphology and reflect the vertical dimension information within 10 min and is aimed to assist dermatologists working with patients suffering from skin diseases via recording or monitoring the skin surface conditions. Additionally, successful trials of loading and electro-controlled release of Cu²⁺ into/from the developed skin patterns reveals its potential to be also utilized for treatment of pathological skin conditions. Based on the developed analytical diagnostic technique, a well-designed 3D printed portable prototype device based on electrosynthesis of the conducting polymer powered by an ordinary battery (1.5 V) was tested and was found to have excellent performance in onsite 3D skin pattern reproduction from live human skin.