Evaluation of mesoporous silica particles as drug carriers in hydrogels

Development and characterization of gastro-floating sustained-release granules for enhanced bioavailability of patchouli oil

Patchouli oil (PO), extracted from Pogostemon cablin Benth., a prominent aromatic plant of the Lamiaceae family, has shown considerable protective effects against gastrointestinal infections, particularly those induced by Helicobacter pylori. This study aimed to develop a gastro-floating multi-unit system for PO to enhance its gastric retention and oral bioavailability.

Methods

The oil-laden granules were prepared using colloidal silicon dioxide (CSD) for oil adsorption and to provide buoyancy, along with ethyl cellulose (EC) and hydroxypropyl methyl cellulose (HPMC) to form a sustained-release matrix. The CSD exhibited favorable characteristics for oil adsorption and floating. Compatibility between PO and CSD was affirmed through DSC thermograms and FTIR spectra. The obtained granules demonstrated a sustained release profile, achieving over 90 % release within 10 h without an initial burst. After oral administration, the granules were observed to remain in the gastric region of rats for over 7 h. The bioavailability of patchouli alcohol from the optimized granules was significantly higher than that from of the PO-loaded powders. The gastro-floating sustained-release granules, based on a CSD/EC/HPMC matrix, offer a simple yet effective strategy to improve the delivery efficacy of PO against Helicobacter pylori infections in the gastric region.

Vancomycin-loaded hydrogels with thermal-responsive, self-peeling, and sustainable antibacterial properties for wound dressing

Wound dressings play an important role in wound healing. However, many wound dressings lack antibacterial properties and are difficult to remove from newly grown tissues, causing secondary wound injuries and repeated medical treatment. This study reports a new type of thermal-responsive hydrogel dressing consisting of vancomycin-loaded gelatin nanospheres (GNs) and poly((N-isopropylacrylamide)-co-N-(methylol acrylamide)) functional components that could impart self-peeling and sustainable antibacterial properties. SEM images showed that the prepared hydrogel possessed a porous microstructure and the homogeneous distribution of GNs in its network. Excellent swelling ratios and thermal-induced self-peeling characteristics were confirmed by qualitative analysis. The GNs not only enhanced the strain at break of the hydrogel, but also acted as drug carriers to slow down the drug release from the hydrogel, achieving sustainable antibacterial properties and balanced biocompatibility. Therefore, this vancomycin-loaded hydrogel with self-peeling characteristics provides an effective way of preventing wound infection and can be used as a novel platform for wide-ranging applications of wound dressings.

Mesoporous Materials Make Hydrogels More Powerful in Biomedicine

Scientists have been attempting to improve the properties of mesoporous materials and expand their application since the 1990s, and the combination with hydrogels, macromolecular biological materials, is one of the research focuses currently. Uniform mesoporous structure, high specific surface area, good biocompatibility, and biodegradability make the combined use of mesoporous materials more suitable for the sustained release of loaded drugs than single hydrogels. As a joint result, they can achieve tumor targeting, tumor environment stimulation responsiveness, and multiple therapeutic platforms such as photothermal therapy and photodynamic therapy. Due to the photothermal conversion ability, mesoporous materials can significantly improve the antibacterial ability of hydrogels and offer a novel photocatalytic antibacterial mode. In bone repair systems, mesoporous materials remarkably strengthen the mineralization and mechanical properties of hydrogels, aside from being used as drug carriers to load and release various bioactivators to promote osteogenesis. In hemostasis, mesoporous materials greatly elevate the water absorption rate of hydrogels, enhance the mechanical strength of the blood clot, and dramatically shorten the bleeding time. As for wound healing and tissue regeneration, incorporating mesoporous materials can be promising for enhancing vessel formation and cell proliferation of hydrogels. In this paper, we introduce the classification and preparation methods of mesoporous material-loaded composite hydrogels and highlight the applications of composite hydrogels in drug delivery, tumor therapy, antibacterial treatment, osteogenesis, hemostasis, and wound healing. We also summarize the latest research progress and point out future research directions. After searching, no research reporting these contents was found.

Embedding Ordered Mesoporous Carbons into Thermosensitive Hydrogels: A Cutting-Edge Strategy to Vehiculate a Cargo and Control Its Release Profile

The high drug loading capacity, cytocompatibility and easy functionalization of ordered mesoporous carbons (OMCs) make them attractive nanocarriers to treat several pathologies. OMCs’ efficiency could be further increased by embedding them into a hydrogel phase for an in loco prolonged drug release. In this work, OMCs were embedded into injectable thermosensitive hydrogels. In detail, rod-like (diameter ca. 250 nm, length ca. 700 nm) and spherical (diameter approximately 120 nm) OMCs were synthesized by nanocasting selected templates and loaded with ibuprofen through a melt infiltration method to achieve complete filling of their pores (100% loading yield). In parallel, an amphiphilic Poloxamer^® 407-based poly(ether urethane) was synthesized (Mn¯ 72 kDa) and solubilized at 15 and 20% w/v concentration in saline solution to design thermosensitive hydrogels. OMC incorporation into the hydrogels (10 mg/mL concentration) did not negatively affect their gelation potential. Hybrid systems successfully released ibuprofen at a slower rate compared to control gels (gels embedding ibuprofen as such), but with no significant differences between rod-like and spherical OMC-loaded gels. OMCs can thus work as effective drug reservoirs that progressively release their payload over time and also upon encapsulation in a hydrogel phase, thus opening the way to their application to treat many different pathological states (e.g., as topical medications).

Development of a Solid Formulation Containing a Microemulsion of a Novel Artemisia Extract with Nematocidal Activity for Oral Administration

Background: Intestinal nematode infections are usually treated with benzimidazole drugs, but the emergence of resistance to these drugs has led to an increasing demand of new anthelmintic strategies. A new microemulsion formulation (ME) consisting of an Artemisia absinthium extract with proven nematocidal efficacy was previously developed. The aim of our study is to implement a D-optimal mixture design methodology to increase the amount of a silica material (loaded with this ME) in a tablet formulation, considering its tensile strength and disintegration time. Methods: 16 experiments or combinations of the 6 tablet components (loaded silica, microcrystalline cellulose, polyvinylpyrrolidone, croscarmellose, Syloid^® 244 FP and magnesium stearate) were assessed. Tensile strength and disintegration time models were developed, and an optimization process was carried out. Results: Tensile strength was improved by increasing the polyvinylpyrrolidone content, while croscarmellose decreased the disintegration time. The optimized powder mixture contains 49.7% w/w of the loaded silica material. A compression force of 12 kN was applied to the powder mixture to form tablets with a tensile strength of 2.0 MPa and a disintegration time of 3.8 min. Conclusions: Our results show that D-optimal mixture designs provide a promising approach to formulate liquid-loaded silica materials.

Injectable Thermosensitive Formulation Based on Polyurethane Hydrogel/Mesoporous Glasses for Sustained Co-Delivery of Functional Ions and Drugs

Mini-invasively injectable hydrogels are widely attracting interest as smart tools for the co-delivery of therapeutic agents targeting different aspects of tissue/organ healing (e.g., neo-angiogenesis, inflammation). In this work, copper-substituted bioactive mesoporous glasses (Cu-MBGs) were prepared as nano- and micro-particles and successfully loaded with ibuprofen through an incipient wetness method (loaded ibuprofen approx. 10% w/w). Injectable hybrid formulations were then developed by dispersing ibuprofen-loaded Cu-MBGs within thermosensitive hydrogels based on a custom-made amphiphilic polyurethane. This procedure showed almost no effects on the gelation potential (gelation at 37 °C within 3-5 min). Cu2+ and ibuprofen were co-released over time in a sustained manner with a significantly lower burst release compared to MBG particles alone (burst release reduction approx. 85% and 65% for ibuprofen and Cu2+, respectively). Additionally, released Cu2+ species triggered polyurethane chemical degradation, thus enabling a possible tuning of gel residence time at the pathological site. The overall results suggest that hybrid injectable thermosensitive gels could be successfully designed for the simultaneous localized co-delivery of multiple therapeutics.

In Vitro and In Vivo Evaluation of Core-Shell Mesoporous Silica as a Promising Water-Insoluble Drug Delivery System: Improving the Dissolution Rate and Bioavailability of Celecoxib With Needle-Like Crystallinity

The objective of our study was to prepare mesoporous silica nanoparticles with a core-shell structure (CSMSNs) and improve the dissolution and bioavailability of celecoxib (Cxb), a water-insoluble drug, by changing its needle-like crystal form. CSMSNs are prepared by a core-shell segmentation self-assembly method. The S_BET and V_t of CSMSNs were 890.65 m²/g and 1.23 cm³/g, respectively. Cxb was incorporated into CSMSNs by the solvent evaporation method. The gastrointestinal irritancy of the CSMSNs was evaluated by a gastric mucosa irritation test. In vitro dissolution and in vivo pharmacokinetic tests were carried out to study the improvement in the dissolution behavior and oral bioavailability of Cxb. In conclusion, gastric mucosa irritation study indicated the good biocompatibility of CSMSNs. The cumulative dissolution of CSMSNs-Cxb is 86.2% within 60 min in SIF solution, which may be ascribed to the crystal form change caused by control of the nanochannel for CSMSNs. Moreover, CSMSNs could enhance the 9.9-fold AUC of Cxb. The cumulative dissolution and bioavailability of Cxb were both significantly enhanced by CSMSNs. CSMSNs with a core-shell structure are suitable as a carrier for a poorly water-soluble drug (Cxb).