Synthesis and characterization of a multi-sensitive polysaccharide hydrogel for drug delivery

ε‑Polylysine-stabilized agarose/polydopamine hydrogel dressings with robust photothermal property for wound healing

Polydopamine (PDA) is emerging as an attractive photothermal agent due to its good photothermal performance and excellent biocompatibility. However, without chemical modification, PDA is normally unstable and usually leached out from the constructed biomaterials, realistically limiting its application space. Here, we constructed a new hydrogel dressing with robust and stable photothermal performance by introduction of ε-Polylysine (ε-PL) into agarose/PDA matrix to efficiently lock PDA. By optimizing PDA/ε-PL rational dose in agarose network structure, a hybrid agarose/PDA/ε-PL hydrogel (ADPH) with stable photothermal functionality and desirable physicochemical properties could be achieved. ADPH possessed satisfactory microbicidal efficacy in vivo, which enabled the bacteria-infected skin wound to be cured quickly by successful suppressing inflammation, accelerating collagen deposition and promoting angiogenesis in a bacterial-infected wound model. Collectively, this study illustrates a simple, convenient but powerful strategy to design functionally stable ADPH dressing for treating dermal wounds, which could open vistas in clinical wound management.

Wound Dressing Hydrogel of Enteromorpha prolifera Polysaccharide-Polyacrylamide Composite: A Facile Transformation of Marine Blooming into Biomedical Material

Great endeavors have been dedicated to the development of wound dressing materials. However, there is still a demand for developing a wound dressing hydrogel that integrates natural macromolecules without requiring extra chemical modifications, so as to enable a facile transformation and practical application in wound healing. Herein, a composite hydrogel was prepared with water-soluble polysaccharides from Enteromorpha prolifera (PEP) cross-linked with boric acid and polyacrylamide cross-linked via polymerization (PAM) using a one-pot method. The dual-network of this hydrogel enabled it to have an ultratough mechanical strength. Moreover, interfacial characterizations reflected that the hydrogen bonds and dynamic hydroxyl-borate bonds contributed to the self-healing ability of the PEP-PAM hydrogel, and the surface groups on the hydrogel allowed for tissue adhesiveness and natural antioxidant properties. Additionally, human epidermal growth factor-loaded PEP-PAM hydrogel promoted cell proliferation and migration in vitro and significantly accelerated wound healing in vivo on model rats. These progresses suggested a prospect for the PEP-PAM hydrogel as an effective and easily available wound dressing material. Remarkably, this work showcases that a wound dressing hydrogel can be facially developed by using natural polysaccharides as a one component and offers a new route for the high-value utilization of disastrous marine blooming biomass by transforming it into a biomedical material.

Fabrication and Characterization of Polysaccharide Metallohydrogel Obtained from Succinoglycan and Trivalent Chromium

In the present study, a polysaccharide metallohydrogel was successfully fabricated using succinoglycan and trivalent chromium and was verified via Fourier transform infrared spectroscopy, differential scanning calorimetry analysis, thermogravimetric analysis (TGA), field emission scanning electron microscopy, and rheological measurements. Thermal behavior analysis via TGA indicated that the final mass loss of pure succinoglycan was 87.8% although it was reduced to 65.8% by forming a hydrogel with trivalent chromium cations. Moreover, succinoglycan-based metallohydrogels exhibited improved mechanical properties based on the added concentration of Cr³⁺ and displayed a 10 times higher compressive stress and enhanced storage modulus (G′) of 230% at the same strain. In addition, the pore size of the obtained SCx could be adjusted by changing the concentration of Cr³⁺. Gelation can also be adjusted based on the initial pH of the metallohydrogel formulation. This was attributed to crosslinking between chromium trivalent ions and hydroxyl/carboxyl groups of succinoglycan, each of which exhibits a specific pH-dependent behavior in aqueous solutions. It could be used as a soft sensor to detect Cr³⁺ in certain biological systems, or as a soft matrix for bioseparation that allows control of pore size and mechanical strength by tuning the Cr³⁺ concentration.

Polymeric antibiofilm coating comprising synergistic combination of citral and thymol prevents methicillin-resistant Staphylococcus aureus biofilm formation on titanium

Biomaterial associated microbial infections are complicated and mostly lead to revision surgery or removal which are painful to the patients and quite expensive. These infections are difficult to treat with antibiotics as it is often related to biofilm formation. Methicillin resistant Staphylococcus aureus (MRSA) is the leading pathogen in biomaterial associated infections and well known to form biofilm on foreign materials. To reduce the risk of biomaterial associated infections, recent treatment strategies focus on modification of the implant surface to prevent the adhesion of bacteria. Antibiofilm coating is the effective approach than coating with antimicrobials as antibiofilm agents will not create selective pressure thereby excludes possibility of drug resistance. The current study identified and validated the synergistic antibiofilm activity of citral (CIT) and thymol (THY) by crystal violet quantification and microscopic analysis without alteration in growth and metabolic viability of MRSA. Polymeric antibiofilm coating with CIT + THY as active ingredients was formulated and coated on titanium surface by the process of spin coating. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the effective blending of polymeric formulation and the presence of CIT and THY. Atomic force microscopy (AFM) images revealed the homogenous coating and reduced surface roughness and thickness of the coating was measured by surface profilometer. Antibiofilm coating released CIT and THY in a sustained manner for 60 days. Antibiofilm coating effectively inhibited MRSA adherence in vitro and antibiofilm activity of coating was not affected by plasma conditioning. In addition, antibiofilm coating was non-hemolytic and non-toxic to PBMC. Thus, the current study demonstrated the effectual strategy to prevent biomaterial associated infections and proposes the prospective role of antibiofilm coating in clinical applications.

Design and applications of protein delivery systems in nanomedicine and tissue engineering

Proteins are biological macromolecules involved in a wide range of biological functions, which makes them very appealing as therapeutics agents. Indeed, compared to small molecule drugs, their endogenous nature ensures their biocompatibility and biodegradability, they can be used in a large range of applications and present a higher specificity and activity. However, they suffer from unfolding, enzymatic degradation, short half-life and poor membrane permeability. To overcome such drawbacks, the development of protein delivery systems to protect, carry and deliver them in a controlled way have emerged importantly these last years. In this review, the formulation of a wide panel of protein delivery systems either in the form of polymer or inorganic nanoengineered colloids and scaffolds are presented and the protein loading and release mechanisms are addressed. A section is also dedicated to the detection of proteins and the characterization methods of their release. Then, the main protein delivery systems developed these last three years for anticancer, tissue engineering or diabetes applications are presented, as well as the major in vivo models used to test them. The last part of this review aims at presenting the perspectives of the field such as the use of protein-rich material or the sequestration of proteins. This part will also deal with less common applications and gene therapy as an indirect method to deliver protein.

Biocompatible and self-recoverable succinoglycan dialdehyde-crosslinked alginate hydrogels for pH-controlled drug delivery

We fabricated polysaccharide-based hydrogels, which are biocompatible, self-recoverable and pH-sensitive. Succinoglycan dialdehyde (SGDA) was first synthesized from bacterial succinoglycan directly isolated from Sinorhizobium meliloti and then hydrazine-functionalized alginate (HZ-Alg) was prepared to form SGDA-crosslinked alginate hydrogels (SGDA/HZ-Alg) without any catalyst. Due to structural characteristics of SGDA, SGDA/HZ-Alg were effectively obtained in a short time even at low concentrations (0.94-1.57 wt%) where they exhibited self-recoverable and tunable rheological properties corresponding to efficiency of recovery from 93.2%-97.9%. Moreover, SGDA/HZ-Alg showed the pH-responsive degradation as well as pH-controlled release behavior for 5-fluorouracil. 5-Fluorouracil was released approximately 98 % at pH 2.0 within 12 h, but not completely released even after 24 h at pH 7.4. The WST-8 assay results also demonstrated that SGDA/HZ-Alg did not show any cytotoxicity against HEK-293 cells. Since the suggested hydrogels are biocompatible, rheologically self-recoverable and tunable, and pH-controllable, they would be potential biomaterials for the hydrogel-based drug delivery systems.

Stimuli-Responsive Biomolecule-Based Hydrogels and Their Applications

This Review presents polysaccharides, oligosaccharides, nucleic acids, peptides, and proteins as functional stimuli-responsive polymer scaffolds that yield hydrogels with controlled stiffness. Different physical or chemical triggers can be used to structurally reconfigure the crosslinking units and control the stiffness of the hydrogels. The integration of stimuli-responsive supramolecular complexes and stimuli-responsive biomolecular units as crosslinkers leads to hybrid hydrogels undergoing reversible triggered transitions across different stiffness states. Different applications of stimuli-responsive biomolecule-based hydrogels are discussed. The assembly of stimuli-responsive biomolecule-based hydrogel films on surfaces and their applications are discussed. The coating of drug-loaded nanoparticles with stimuli-responsive hydrogels for controlled drug release is also presented.

Construction of functional curdlan hydrogels with bio-inspired polydopamine for synergistic periodontal antibacterial therapeutics

Curdlan, a bacteria-derived polysaccharide resource, possesses substantial potential for periodontal antimicrobial delivery. Here, the facile engineering of a functionalized curdlan/polydopamine (PDA) composite hydrogels was reported. The physiochemical evaluations of composite hydrogels proved their tunable properties associated with concentration of PDA including pore size, rheological property and swelling behavior. We have systematically assessed biocompatibility in vitro and found these hydrogels toxicity-free. Moreover, photothermal performance upon near infrared light (NIR) exposure was conducted and eventually indicated the best matches for antibacterial application. The acetate chlorhexidine (CHX) was chosen as a model antimicrobial and the release profiles demonstrated the entrapped CHX could be triggered and nicely controlled by NIR. The optimized bacteriostatic rate reached 99.9 %. Overall, we aimed to provide new curdlan-based hydrogels for periodontal antibacterial treatment by combining photothermal effect and antimicrobial simultaneously.

Biocompatible Hydrogels Based on Food Gums with Tunable Physicochemical Properties as Scaffolds for Cell Culture

Hydrogels composed of food gums have gained attention for future biomedical applications, such as targeted delivery and tissue engineering. For their translation to clinical utilization, reliable biocompatibility, sufficient mechanical performance, and tunable structure of polysaccharide hydrogels are required aspects. In this work, we report a unique hybrid polysaccharide hydrogel composed of salecan and curdlan, in which the former is a thickening agent and the latter serves as a network matrix. The physicochemical properties, such as mechanical strength, thermal stability, swelling, and morphology, of the developed composite hydrogel can be accurately modulated by varying the polysaccharide content. Importantly, cytotoxicity assays show the non-toxicity of this hybrid hydrogel. Furthermore, this hydrogel system can support cell proliferation, migration, and function. Altogether, our work proposes a new strategy to build a polysaccharide-constructed hydrogel scaffold, which holds much promise for tissue engineering in terms of cell engraftment, survival, proliferation, and function.

Macroporous Hydrogel Scaffolds with Tunable Physicochemical Properties for Tissue Engineering Constructed Using Renewable Polysaccharides

Polysaccharides have recently attracted increasing attention in the construction of hydrogel devices for biomedical applications. However, polysaccharide-based hydrogels are not suitable for most preclinical applications because of their limited mechanical properties and poor tunability. In this study, we employed a simple and eco-friendly approach to producing a macroporous polysaccharide hydrogel composed of salecan and κ-carrageenan without the use of toxic chemicals. We evaluated the physicochemical properties of the obtained salecan/κ-carrageenan hydrogel and found that its viscoelasticity, morphology, swelling, and thermal stability could be simply controlled by changing the polysaccharide dose in the pre-gel solution. The co-incubation of the fabricated hydrogel with mouse fibroblast cells demonstrated that the hydrogel can support cell adhesion, migration, and growth. Moreover, the hydrogel exhibited good biocompatibility in vivo. Overall, the findings provide a new strategy for the fabrication and optimization of polysaccharide-based hydrogel scaffolds for application in tissue engineering.

Multiple stimuli-switchable electrocatalysis and logic gates of rutin based on semi-interpenetrating polymer network hydrogel films

The switching properties of PAA–PDEA films polymerized as a semi-IPN were studied with rutin as a probe and a logic gate was constructed.

Radiation development of pH-responsive (xanthan-acrylic acid)/MgO nanocomposite hydrogels for controlled delivery of methotrexate anticancer drug

Nanocomposite hydrogels composed of magnesium oxide (MgO) and natural polymer-based copolymer of Xanthan gum (Xan) and acrylic acid (AAc) were prepared using radiation-induced copolymerization and crosslinking technique to be used as a drug delivery system. MgO nanoparticles were synthesized using sol- gel method. FTIR, XRD, UV-vis and TEM analysis revealed the successful preparation of MgO nanoparticles. The size of MgO nanoparticles was found to be 6.6 nm. FTIR data confirmed the incorporation of MgO within the (Xan-AAc) copolymer hydrogel. The presence of MgO nanoparticles slightly decreases the gelation degree and on contrary the swelling degree and network porosity was enhanced. (Xan-AAc)/MgO nanocomposites show typical pH-dependent swelling behavior Moreover, the swelling kinetics showed that all the samples under investigation possess Fickian at pH1 and non-Fickian at pH7. Methotrexate (MTX) as model for anticancer drugs was used to evaluate the potential efficiency of the obtained (Xan-AAc)/MgO nanocomposites as drug carrier. Incorporation of MgO into (Xan-AAc) hydrogel improves the drug loading efficiency and enhances the (MTX) release to reach maximum in the simulated intestine medium (pH7). The drug release profile came in a good agreement with swelling results which recommend the (Xan-AAc)/MgO nanocomposite hydrogels as potential targeted drug delivery system.

In vitro study of chitosan-based multi-responsive hydrogels as drug release vehicles: a preclinical study

Systematic administration of painkillers and anti-inflammatory drugs is routinely employed to minimize pain and bodily disorders. Controlled drug delivery has the potential to improve the outcomes of disorders by providing sustained exposure to efficacious drug concentrations. Herein, we report the fabrication of multi-responsive hydrogels using reactive and functional polymers such as chitosan and polyvinyl pyrrolidone by varying the concentration of a cleavable crosslinker, tetraethyl orthosilicate. The swelling indices of the hydrogels were evaluated in distilled water, solutions with different pH values and different electrolytes. FTIR, WAXRD and TGA were conducted to investigate the structures, crystallinities and thermal stabilities of the prepared multi-responsive hydrogels, respectively. The ultimate tensile strength and elongations at break of the fabricated hydrogels were investigated to assess their mechanical stability. Optical microscopy, biodegradation, antimicrobial and cytotoxicity analyses were further carried out to verify the magnified crosslinked and porous structures, biodegradabilities, biocompatibilities and toxic behaviour of the as-prepared hydrogels, respectively. Drug release analysis was conducted to evaluate their release behaviour in PBS, SGF, SIF and electrolyte solutions. The overall results indicate the successful development of novel, non-toxic and sustained drug deliverable hydrogels, which can be considered as a paramount success towards the fabrication of controlled drug delivery systems.

Highly efficient dye decontamination via microbial salecan polysaccharide-based gels

Wastewater treatment materials that combine high decontamination performance, ease of use and economic production are highly desirable for practical applications. Herein, we fabricated a low-cost and recyclable bio-adsorbent based on a microbial polysaccharide (salecan) for efficient removal of methyl violet (MV) from wastewater. The success fabrication and the properties (such as thermal stability, microarchitecture, mechanical strength and water uptake) of the adsorbent had been investigated, and the hydrogels were found to have tunable properties by simple adjusting the salecan dose in hydrogel composition. Adsorption data displayed that the adsorption of MV followed the pseudo second-order kinetic model (R² = 0.99015) and Freundlich isotherm model (R² = 0.99221) with a maximum adsorption capacity of 178.9 mg/g. Moreover, salecan-based hydrogels showed a good reversibility in adsorption-desorption cycles. These features indicate that salecan-based bio-adsorbent may be a promising device for dye removal from dyeing waste water.

Controlled release studies through chitosan-based hydrogel synthesized at different polymerization stages

An earlier study showed that the behaviour of chitosan-poly(methacrylic acid‑co‑N‑isopropylacrylamide) [chitosan‑p(MAA‑co‑NIPAM)] hydrogels synthesized at different reaction times are affected with regard to their pH and temperature sensitivities. The study was continued in this paper to identify the effects of different reaction times on the degradation, efficiency of rifampicin (Rif) loading and the Rif release profile under two different pH conditions (acidic and basic). The results that were obtained showed that the hydrogel had a faster degradation rate in the acidic condition than in the basic condition, where there was a loss of approximately 50% and 20%, respectively in its original weight within two weeks. The Rif loading efficiency was within 50% and the drug release was controlled by characteristics that were developed beyond the polymerization stages of the synthesis. Therefore, the reaction time for the synthesis of the hydrogel can be considered as a way to control the behaviour of the hydrogel as well as to modify the drug release profile in the chitosan‑p(MAA‑co‑NIPAM) hydrogel.

Salecan polysaccharide-based hydrogels and their applications: a review

This review systematically summarizes for the first time the recent progress on hydrogels containing salecan polysaccharides.

Applying emerging technologies to improve diabetes treatment

Insulin, as the most important drug for the treatment of diabetes, can effectively control the blood glucose concentration in humans. Due to its instability, short half-life, easy denaturation and side effects, the administration way of insulin are limited to subcutaneous injection accompany with poor glucose control and low patient compliance. In recent years, emerging insulin delivery systems have been developed in diabetes research. In this review, a variety of stimuli-responsive insulin delivery systems with their response mechanism and regulation principle are described. Further, the introduction of stem cell transplantation and mobile application based delivery technologies are prudent for the diabetes treatment. This article also discusses the advantages and limitations of current strategies, along with the opportunities and challenges for future insulin therapy.

Thermosensitive Behavior and Super-Antibacterial Properties of Cotton Fabrics Modified with a Sercin-NIPAAm-AgNPs Interpenetrating Polymer Network Hydrogel

Poly(N-isopropylacrylamide) (PNIPAAm), sericin (SS), and silver nitrate were combined to prepare an interpenetrating network (IPN) hydrogel having dual functions of temperature sensitivity and antibacterial properties. The structure and size of AgNPs in such an IPN hydrogel were characterized by the Fourier Transform Infrared spectrum (FT-IR), X-ray powder diffraction (XRD) and Transmission Electron Microscope (TEM), and the thermal properties of the IPN hydrogel were characterized by Differential Scanning Calorimetry (DSC). Based on XRD patterns, Ag⁺ was successfully reduced to Ag⁰ by SS. It was observed by TEM that the particle size of silver particles was lower than 100 nm. The glass transition temperature (Tg) of IPN hydrogel was better than that of the PNIPAAm/AgNPs hydrogels, and lower critical solution temperature (LCST) values of the IPN hydrogel were obtained by DSC i.e. 31 °C. The thermal stability of the IPN hydrogel was successfully determined by the TGA. This IPN hydrogel was then used to modify the cotton fabrics by the "impregnation" method using glutaraldehyde (GA) as the cross-linking agent. The structures and properties of IPN hydrogel modified cotton fabric were characterized by scanning electron microscopy (SEM), FT-IR, and the thermogravimetry analysis (TGA). The results show that NIPAAm was successfully polymerized into PNIPAAm, and that there were neglected new groups in the hydrogel IPN. The IPN hydrogel was then successfully grafted onto cotton fabrics. SEM observations showed that the IPN hydrogel formed a membrane structure between the fibers, and improved the compactness of the fibers. At the temperature close to LCST (≈31 °C), the entire system was easily able to absorb water molecules. However, the hydrophilicity tended to decrease when the temperature was higher or lower than the LCST. The antibacterial rates of the modified cotton fabric against S. aureus and E. coli were as high as 99%.

Polysaccharide-based cationic hydrogels for dye adsorption

With advances in soft material design and engineering, naturally resourced polysaccharides have frequently been used to construct hydrogels because of their unique properties such as renewability, biodegradability and biocompatibility. In this work, we use a water-soluble microbial polysaccharide, salecan as a trapped natural polymer, poly(acrylamide-co-diallyldimethylammonium chloride) (PAD) as a functional matrix to prepare salecan/PAD hydrogels through a facile one-pot method. We employed a variety of spectroscopic techniques to probe the physicochemical properties of the designed hydrogels. The results demonstrated that salecan not only tuned the polarity of the PAD hydrogels, but also endowed them with adjustable water content. Subsequently, the adsorption performance of these hydrogels to methyl orange (MO) dye was investigated in detail. It was found that the salecan/PAD had the ability to remove MO from the surrounding aqueous solutions. In addition, adsorption kinetic data were nicely described by pseudo-second-order model and the adsorption isotherm data fitted well with the Freundlich equation. Having tailorable physicochemical properties coupled with the ability to uptake dye, these salecan-incorporated hydrogels could be promising platform for wastewater treatment and removal of heavy metal ions.

Preparation of a novel palladium catalytic hydrogel based on graphene oxide/chitosan NPs and cellulose nanowhiskers

Pd NPs dispersed on a polysaccharide-based hydrogel as a novel catalyst show high catalytic activity and recyclability for coupling reactions.