Controlled release of ascorbic acid from genipin-crosslinked gelatin matrices under moving boundary conditions

Soft and flexible polyvinyl alcohol/pullulan aerogels with fast and high water absorption capacity for facial mask substrates

Facial mask substrates commonly used in skincare are often considered unhealthy and environmentally unfriendly due to their composition of premoistened nonwovens containing various preservatives. This study aims to address this issue by developing a preservative-free degradable aerogel made from polyvinyl alcohol (PVA)/pullulan (PUL) using a unidirectional freeze-drying method. The aerogels had ordered three-dimensional porous structures and exhibited desirable mechanical properties. They were soft and flexible in both dry and wet states, and their Young's moduli were comparable to that of human skin. The aerogels had high porosity, ranging from 93.0 % to 95.1 %, and exhibited a high water absorption rate and water absorption capacity (ranging from 7.5 g/g to 10.1 g/g). After 30 min of water evaporation, the aerogels showed excellent moisture retention, ranging from 88 % to 93 %. Additionally, the PVA/PUL aerogel efficiently loaded and released active ingredients, such as rapidly releasing ascorbic acid (> 90 % within 30 min). These findings suggest that the PVA/PUL aerogel has potential as a material for facial mask substrates.

Fundamental advances in hydrogels for the development of the next generation of smart delivery systems as biopharmaceuticals

Recent advances in developing and applying therapeutic peptides for anticancer, antimicrobial and immunomodulatory remedies have opened a new era in therapeutics. This development has resulted in the engineering of new biologics as part of a concerted effort by the pharmaceutical industry. Many alternative routes of administration and delivery vehicles, targeting better patient compliance and optimal therapeutic bioavailability, have emerged. However, the design of drug delivery systems to protect a range of unstable macromolecules, including peptides and proteins, from high temperatures, acidic environments, and enzymatic degradation remains a priority. Herein, we give chronological insights in the development of controlled-release drug delivery systems that occurred in the last 70 years or so. Subsequently, we summarise the key physicochemical characteristics of hydrogels contributing to the development of protective delivery systems concerning drug-targeted delivery in the chronospatial domain for biopharmaceuticals. Furthermore, we shed some light on promising hydrogels that can be utilised for systemic bioactive administration.

The effect of trisodium phosphate crosslinking on the diffusion kinetics of caffeine from chitosan networks

This work examines the relationship between microstructural properties of hot-moulded chitosan networks, crosslinked with trisodium phosphate, and diffusive behaviour from these networks. Analysis through infrared spectroscopy (FTIR) confirmed successful crosslinking of the polymer chains and bioactive entrapment, while X-ray diffraction (WAXD) and dynamic oscillation in-shear elucidated the higher order structural properties of each matrix, as they transitioned from solutions to amorphous gels to semi-crystalline matrices. The picture of molecular motion observed in these systems and consequent application of the Flory-Rehner theory further indicated that different extents of chitosan crosslinking yielded a distinct water infusion functionality seen in the levels of swelling. Diffusion of caffeine from these delivery vehicles showed that network structural properties (governed by crosslinker concentration) had a significant effect on the release kinetics of the entrapped bioactive. The relationship between network mesh characteristics and diffusion properties were further confirmed by correlating caffeine release rates and molecular pore size.

Coordination with zirconium: A facile approach to improve the mechanical properties and thermostability of gelatin hydrogel

The poor mechanical property and thermostability restricted applications of gelatin hydrogel. Herein, a facile and inexpensive approach of immerging cooling induced gelatin hydrogels into Zr(SO₄)₂ dilute solution was applied to overcome these shortages. After this treatment, the micropores in hydrogel decreased to tens of microns while the water content slightly decreased. XPS results revealed that the coordination bonds formed between amino or carboxyl groups of gelatins and Zr⁴⁺. After immerging in 0.06 M Zr⁴⁺ solution, mechanical tests showed that the elastic modulus, compressive modulus and compressive strength of hydrogel were about 400, 1192 and 476 kPa, respectively, which were approximate 100, 11 and 5 times larger than those of pure gelatin. The DSC data indicated that the thermoreversible temperature of triple helix structure in gelatin was improved from about 30 °C to 55 °C. More importantly, the rheological temperature sweep test revealed that hydrogels with 0.06 M Zr⁴⁺ treatment can maintain the hydrogel state without melting even at 80 °C. CCK-8 tests and Calcein-AM/PI double-stain experiments demonstrated Zr⁴⁺ coordination was non-cytotoxic. These promising data indicated this nontoxic method was efficient and had potential to fabricate gelatin related materials for further application.

The preparation of hydroxyapatite nanowires and nanorods via aliphatic micelles as soft templates

Hydroxyapatite nanoparticles were tunably synthesized via the use of an aliphatic–ethanol–water three-phase mixture system using micelles as soft templates via an emulsion–hydrothermal synergistic method.

Synthesis of Agarose-Based Multistimuli-Responsive Hydrogel Dressing for Accelerated Wound Healing

Stimuli-responsive hydrogels have drawn increasing research interest in regenerative medicine due to their tunable molecular structures and functional properties for both providing a suitable microenvironment for wound healing and to serve as a sustainable therapeutic. Hence, we developed a stimuli-responsive drug-loaded hydrogel wound dressing for sustained, controlled release of the drug and accelerating wound healing. Hydrogel dressings with stimuli-responsive properties were prepared using carboxymethyl agarose (CMA) with various degrees of substitution and calcium ion crosslinking, followed by the loading of recombinant human epidermal growth factor (Rh-EGF) on the CMA hydrogel. Experimental results indicated that these hydrogel composites showed pH and temperature stimuli-responsive behaviors and released the encapsulated drug sustainedly in various release media. Moreover, the hydrogel dressings exhibited a porous network structure, stable physical properties, and excellent biocompatibility. The investigation in vivo showed that the Rh-EGF-loaded CMA hydrogel dressing significantly enhanced wound healing and reduced inflammatory responses by upregulating the transforming growth factor-beta, vascular endothelial growth factor, and cluster of differentiation 31 (CD31). These results confirm that Rh-EGF-loaded CMA hydrogel dressings possess potential application in accelerating wound healing and tissue regeneration.

Curcumin-Functionalized Gelatin Films: Antioxidant Materials with Modulated Physico-Chemical Properties

In this paper we used curcumin as a functionalizing agent of gelatin films with the aim to get antioxidant materials with modulated physico-chemical properties. To this aim, we prepared gelatin films at different contents of curcumin up to about 1.2 wt%. The as-prepared films, as well as glutaraldehyde crosslinked films, were submitted to several tests: swelling, water solubility, differential scanning calorimetry, X-ray diffraction, mechanical tests and curcumin release. The radical scavenging activity of the as-prepared films is similar to that of free curcumin, indicating remarkable antioxidant properties. All the other tested properties vary as a function of curcumin content and/or the presence of the crosslinking agent. In particular, the films exhibit sustained curcumin release in different solvents. Thanks to its biocompatibility, biodegradability and lack of antigenicity, gelatin uses span from food processing to packaging and biomaterials. It follows that the modulated properties exhibited by the functionalized materials developed in this work can be usefully employed in different application fields.

Genipin-cross-linked hydrogels based on biomaterials for drug delivery: a review

Genipin is a naturally occurring nontoxic cross-linker, which has been widely used for drug delivery due to its excellent biocompatibility, admirable biodegradability and stable cross-linked attributes. These advantages led to its extensive application in the fabrication of hydrogels for drug delivery. This review describes the physicochemical characteristics and pharmacological activities of genipin and attempts to elucidate the detailed mechanisms of the cross-linking reaction between genipin and biomaterials. The current article entails a general review of the different biomaterials cross-linked by genipin: chitosan and its derivatives, collagen, gelatin, etc. The genipin-cross-linked hydrogels for various pharmaceutical applications, including ocular drug delivery, buccal drug delivery, oral drug delivery, anti-inflammatory drug delivery, and antibiotic and antifungal drug delivery, are reported. Finally, the future research directions and challenges of genipin-cross-linked hydrogels for pharmaceutical applications are also discussed in this review.

Modeling the release of food bioactive ingredients from carriers/nanocarriers by the empirical, semiempirical, and mechanistic models

The encapsulation process has been utilized in the field of food technology to enhance the technofunctional properties of food products and the delivery of nutraceutical ingredients via food into the human body. The latter application is very similar to drug delivery systems. The inherent sophisticated nature of release mechanisms requires the utilization of mathematical equations and statistics to predict the release behavior during the time. The science of mathematical modeling of controlled release has gained a tremendous advancement in drug delivery in recent years. Many of these modeling methods could be transferred to food. In order to develop and design enhanced food controlled/targeted bioactive release systems, understanding of the underlying physiological and chemical processes, mechanisms, and principles of release and applying the knowledge gained in the pharmaceutical field to food products is a big challenge. Ideally, by using an appropriate mathematical model, the formulation parameters could be predicted to achieve a specific release behavior. So, designing new products could be optimized. Many papers are dealing with encapsulation approaches and evaluation of the impact of process and the utilized system on release characteristics of encapsulated food bioactives, but still, there is no deep insight into the mathematical release modeling of encapsulated food materials. In this study, information gained from the pharmaceutical field is collected and discussed to investigate the probable application in the food industry.

A review on techniques utilized for design of controlled release food active packaging

Active packaging (AP) is a new class of innovative food packaging, containing bioactive compounds, is able to maintain the quality of food and extend its shelf life by releasing active agent during storage. The main challenge in designing the AP system is slowing the release rate of active compounds for its prolonged activity. Controlled-release active packaging (CRP) is an innovative technology that provides control in the release of active compounds during storage. Various approaches have been proposed to design CRP. The purpose of this review was to gather and present the strategies utilized for release controlling of active compounds from food AP systems. The chemical modification of polymers, the preparation of multilayer films and the use of cross-linking agents are some methods tried in the last decades. Other approaches use molecular complexes and irradiation treatments. Micro- or nano-encapsulation of active compounds and using nano-structured materials in the AP film matrix are the newest techniques used for the preparation of CRP systems. The action mechanism for each technique was described and an effort was made to highlight representative published papers about each release controlling approach. This review will benefit future prospects of exploring other innovative release controlling methods in food CRP.

Molecular Functionality of Plant Proteins from Low- to High-Solid Systems with Ligand and Co-Solute

In the food industry, proteins are regarded as multifunctional systems whose bioactive hetero-polymeric properties are affected by physicochemical interactions with the surrounding components in formulations. Due to their nutritional value, plant proteins are increasingly considered by the new product developer to provide three-dimensional assemblies of required structure, texture, solubility and interfacial/bulk stability with physical, chemical or enzymatic treatment. This molecular flexibility allows them to form systems for the preservation of fresh food, retention of good nutrition and interaction with a range of microconstituents. While, animal- and milk-based proteins have been widely discussed in the literature, the role of plant proteins in the development of functional foods with enhanced nutritional profile and targeted physiological effects can be further explored. This review aims to look into the molecular functionality of plant proteins in relation to the transport of bioactive ingredients and interaction with other ligands and proteins. In doing so, it will consider preparations from low- to high-solids and the effect of structural transformation via gelation, phase separation and vitrification on protein functionality as a delivery vehicle or heterologous complex. Applications for the design of novel functional foods and nutraceuticals will also be discussed.