k-Carrageenan/sericin-based multiparticulate systems: A novel gastro-resistant polymer matrix for indomethacin delivery

In Situ Structural Densification of Hydrogel Network and Its Interface with Electrodes for High-Performance Multimodal Artificial Skin

The multisensory responsiveness of hydrogels positions them as promising candidates for artificial skin, whereas the mismatch of modulus between soft hydrogels and hard electrodes as well as the poor adhesion and conductance at the interface greatly impairs the stability of electronics devices. Herein, we propose an in situ postprocessing approach utilizing electrochemical reactions between metals (Zn, etc.) and hydrogels to synergistically achieve strong adhesion of the hydrogel-electrode interface, low interfacial impedance, and local strain isolation due to the structural densification of the hydrogel network. The mechanism is that Zn electrochemically oxidizes to Zn2+ and injects into the hydrogel, gradually forming a mechanically interlocked structure, Zn2+-polymer dual-helix structural nodes, and a high-modulus ZnO from the surface to the interior. Compared to untreated samples, the treated sample displays 8.7 times increased interfacial adhesion energy between the hydrogel and electrode (87 J/m2), 95% decreased interfacial impedance (218.8 Ω), and a high-strain isolation efficiency (εtotal/εisolation > 400). Akin to human skin, the prepared sensor demonstrates multimodal sensing capabilities, encompassing highly sensitive strain perception and simultaneous perception of temperature, humidity, and oxygen content unaffected by strain interference. This easy on-chip preparation of hydrogel-based multimodal sensor array shows great potential for health and environment monitoring as artificial skin.

Self-assembly mucoadhesive beads of κ-carrageenan/sericin for indomethacin oral extended release

Oral drug administration, especially when composed of mucoadhesive delivery systems, has been a research trend due to increased residence time and contact with the mucosa, potentially increasing drug bioavailability and stability. In this context, this study aimed to develop self-assembly mucoadhesive beads composed of blends of κ-carrageenan and sericin (κ-Car/Ser) loaded with the anti-inflammatory drug indomethacin (IND). We investigated the swelling, adhesion behaviour, and mechanical/physical properties of the beads, assessing their effects on cell viability, safety and permeation characteristics in both 2D and triple-culture model. The swelling ratio of the beads indicated pH-responsiveness, with maximum water absorption at pH 6.8, and strong mucoadhesion, increasing primarily with higher polymer concentrations. The beads exhibited thermal stability and no chemical interaction with IND, showing improved mechanical properties. Furthermore, the beads remained stable during accelerated and long-term storage studies. The beads were found to be biocompatible, and IND encapsulation improved cell viability (>70 % in both models, 79 % in VN) and modified IND permeation through the models (6.3 % for F5 formulation (κ-Car 0.90 % w/v | Ser 1.2 % w/v| IND 3.0 g); 10.9 % for free IND, p < 0.05). Accordingly, κ-Car/Ser/IND beads were demonstrated to be a promising IND drug carrier to improve oral administration while mitigating the side effects of non-steroidal anti-inflammatories.

κ-Carrageenan/sericin polymer matrix modified with different crosslinking agents and thermal crosslinking: Improved release profile of mefenamic acid

The crosslinking of the polymer matrix with compatible macromolecules results in a three-dimensional network structure that offers an enhancement in the controlled release properties of the material. In this sense, this work aimed to improve the release profile of mefenamic acid (MAC) through crosslinking strategies. κ-Carrageenan/sericin crosslinked blend was obtained by covalent and thermal crosslinking and the different formulations were characterized. The gastroresistant potential and release profile were evaluated in the dissolution assay. The effect and characterization of the particles were investigated. Multiple units presented high entrapment efficiency (94.11-104.25), high drug loading (36.50-47.50 %) and adequate particle size (1.34-1.57 mm) with rough surface and visually spherical shape. The Weibull model showed that drug release occurred by relaxation, erosion and Fickian diffusion. Material stability and absence of MAC -polymer interactions were demonstrated by FTIR and thermogravimetric analysis. DSC showed a stable character of MAC in the drug-loaded beads. Moreover, the application studies of κ-Car/Ser/carboxymethylcellulose in the in vitro intestine mode showed that the crosslinked blend increased cell viability (>85 %), while free MAC exhibited a cytotoxic effect. Finally, the crosslinked k-Car/Ser blend MAC -loaded showed promising properties of a sustained release form of anti-inflammatory drug.

Development and characterization of crosslinked k-carrageenan/sericin blend with covalent agents or thermal crosslink for indomethacin extended release

Modified release of multiparticulate pharmaceutical forms is a key therapeutic strategy to reduce side effects and toxicity caused by high and repeated doses of immediate-release oral drugs. This research focused on the encapsulation of indomethacin (IND) in the crosslinked k-Car/Ser polymeric matrix by covalent and thermal methods to evaluate drug delivery modulation and properties of the crosslinked blend. Therefore, the entrapment efficiency (EE %), drug loading (DL %) and physicochemical properties of the particles were investigated. The particles presented a spherical shape and a rough surface with a mean diameter of 1.38-2.15 mm (CCA) and 1.56-1.86 mm (thermal crosslink). FTIR investigation indicated the presence of IDM in the particles and X-ray pattern showed the maintenance of crystallinity of IDM. The in vitro release in acidic medium (pH 1.2) and phosphate buffer saline solution (pH 6.8) was 1.23-6.81 % and 81-100 %, respectively. Considering the results, the formulations remained stable after 6 months. The Weibull equation was adequately fitted for all formulations and a diffusion mechanism, swelling and relaxation of chain were observed. IDM-loaded k-carrageenan/sericin/CMC increases cell viability (> 75 % for neutral red and > 81 % for MTT). Finally, all formulations present gastro-resistance, pH response and altered release and have the potential to be used as drug delivery careers.