A physically crosslinked polydopamine/nanocellulose hydrogel as potential versatile vehicles for drug delivery and wound healing

Preparation of Agarose Fluorescent Hydrogel Inserted by POSS and Its Application for the Identification and Adsorption of Fe3

After entering in water, Fe3+ is enriched in the human body and along the food chain, causing chronic poisoning and irreversible harm to human health. In order to solve this problem, we synthesized citric acid POSS (CAP) from aminopropyl POSS (OAP) and citric acid. Then, we synthesized fluorescent hydrogels (CAP-agarose hydrogel, CAHG) with CAP and agarose. The luminescence mechanism of CAP was investigated by theoretical calculation. CAP plays a dual role in composite hydrogels: one is to give the gels good fluorescence properties and detect Fe3+; the second is that the surface of CAP has a large content of carbonyl and amide groups, so it can coordinate with Fe3+ to enhance the adsorption properties of hydrogels. The experimental results show that the lowest Fe3+ concentration that CAHG can detect is 5 μmol/L, and the adsorption capacity for Fe3+ is about 26.75 mg/g. In a certain range, the fluorescence intensity of CAHG had an exponential relation with Fe3+ concentration, which is expected to be applied to fluorescence sensors. Even at a lower concentration, CAHG can effectively remove Fe3+ from the solution. The prepared fluorescent hydrogel has great potential in the field of fluorescent probes, fluorescent sensors, and ion adsorption. Besides, CAHG can be used as photothermal material after adsorbing Fe3+, allowing for material recycling and reducing material waste.

An excellent antibacterial and high self-adhesive hydrogel can promote wound fully healing driven by its shrinkage under NIR

The lacks of antibacterial properties, low adhesion and delayed wound healing of the hydrogel wound dressings limit their applications in wound treatment. To resolve these, a novel hydrogel composed of polydopamine (PDA), Ag and graphene oxide (GO) is fabricated for wound dressing via the chemical crosslinking of N-isopropylacrylamide (NIPAM) and N,N'-methylene bisacrylamide (BIS). The prepared hydrogel containing PDA@Ag5GO1 (Ag5GO1 denotes the mass ratio between Ag and GO is 5:1) exhibits effective antibacterial properties and high inhibition rate against E. coli and S. aureus. It shows high adhesion ability to various substrate materials, implying a simpler method to the wound obtained by self-fixing rather than suturing. More important, it can produce strong contractility under the irradiation of near-infrared light (NIR), exerting a centripetal force that helps accelerate wound healing. Thus, the hydrogel containing a high concentration PDA@Ag5GO1 irradiated by NIR can completely repair the wound defect (1.0 × 1.0 cm²) within 15 days, the wound healing rate can reach 100%, which was far higher than other groups. Taken together, the new hydrogel with excellent antibacterial, high adhesion and strong contractility will subvert the traditional treatment methods on wound defect, extending its new application range in wound dressing.

Smart near infrared-responsive nanocomposite hydrogels for therapeutics and diagnostics

Nanocomposite (NC) hydrogels are emerging biomaterials that possess desirable and defined properties and functions for therapeutics and diagnostics. Particularly, nanoparticles (NPs) are employed as stimulus-transducers in NC hydrogels to facilitate the treatment process by providing controllable structural change and payload release under internal and external simulations. Among the various external stimuli, near-infrared (NIR) light has attracted considerable interest due to its minimal photo-damage, deep tissue penetration, low auto-fluorescence in living systems, facile on/off switch, easy remote and spatiotemporal control. In this study, we discuss four types of transducing nanomaterials used in NIR-responsive NC hydrogels, including metal-based nanoparticles, carbon-based nanomaterials, polydopamine nanoparticles (PDA NPs), and upconversion nanoparticles (UCNPs). This review provides an overview of the current progress in NIR-responsive NC hydrogels, focusing on their preparation, properties, applications, and future prospects.

Functional Hydrogels as Wound Dressing to Enhance Wound Healing

Hydrogels, due to their excellent biochemical and mechnical property, have shown attractive advantages in the field of wound dressings. However, a comprehensive review of the functional hydrogel as a wound dressing is still lacking. This work first summarizes the skin wound healing process and relates evaluation parameters and then reviews the advanced functions of hydrogel dressings such as antimicrobial property, adhesion and hemostasis, anti-inflammatory and anti-oxidation, substance delivery, self-healing, stimulus response, conductivity, and the recently emerged wound monitoring feature, and the strategies adopted to achieve these functions are all classified and discussed. Furthermore, applications of hydrogel wound dressing for the treatment of different types of wounds such as incisional wound and the excisional wound are summarized. Chronic wounds are also mentioned, and the focus of attention on infected wounds, burn wounds, and diabetic wounds is discussed. Finally, the future directions of hydrogel wound dressings for wound healing are further proposed.

Dialdehyde Nanocrystalline Cellulose as Antibiotic Substitutes against Multidrug-Resistant Bacteria

Antibiotic abuse resulted in the emergence of multidrug-resistant Gram-positive pathogens, which pose a severe threat to public health. It is urgent to develop antibiotic substitutes to kill multidrug-resistant Gram-positive pathogens effectively. Herein, the antibacterial dialdehyde nanocrystalline cellulose (DNC) was prepared and characterized. The antibacterial activity and biosafety of DNC were studied. With the increasing content of aldehyde groups, DNC exhibited high antibacterial activity against Gram-positive pathogens in vitro. DNC3 significantly reduced the amounts of methicillin-resistant Staphylococcus aureus (MRSA) on the skin of infected mice models, which showed low cytotoxicity, excellent skin compatibility, and no acute oral toxicity. DNC exhibited potentials as antibiotic substitutes to fight against multidrug-resistant bacteria, such as ingredients in salves to treat skin infection and other on-skin applications.

Advanced Functional Materials Based on Nanocellulose for Pharmaceutical/Medical Applications

Nanocelluloses (NCs), with their remarkable characteristics, have proven to be one of the most promising "green" materials of our times and have received special attention from researchers in nanomaterials. A diversity of new functional materials with a wide range of biomedical applications has been designed based on the most desirable properties of NCs, such as biocompatibility, biodegradability, and their special physicochemical properties. In this context and under the pressure of rapid development of this field, it is imperative to synthesize the successes and the new requirements in a comprehensive review. The first part of this work provides a brief review of the characteristics of the NCs (cellulose nanocrystals-CNC, cellulose nanofibrils-CNF, and bacterial nanocellulose-BNC), as well as of the main functional materials based on NCs (hydrogels, nanogels, and nanocomposites). The second part presents an extensive review of research over the past five years on promising pharmaceutical and medical applications of nanocellulose-based materials, which have been discussed in three important areas: drug-delivery systems, materials for wound-healing applications, as well as tissue engineering. Finally, an in-depth assessment of the in vitro and in vivo cytotoxicity of NCs-based materials, as well as the challenges related to their biodegradability, is performed.

Nanocelluloses: Sources, Pretreatment, Isolations, Modification, and Its Application as the Drug Carriers

The 'Back-to-nature' concept has currently been adopted intensively in various industries, especially the pharmaceutical industry. In the past few decades, the overuse of synthetic chemicals has caused severe damage to the environment and ecosystem. One class of natural materials developed to substitute artificial chemicals in the pharmaceutical industries is the natural polymers, including cellulose and its derivatives. The development of nanocelluloses as nanocarriers in drug delivery systems has reached an advanced stage. Cellulose nanofiber (CNF), nanocrystal cellulose (NCC), and bacterial nanocellulose (BC) are the most common nanocellulose used as nanocarriers in drug delivery systems. Modification and functionalization using various processes and chemicals have been carried out to increase the adsorption and drug delivery performance of nanocellulose. Nanocellulose may be attached to the drug by physical interaction or chemical functionalization for covalent drug binding. Current development of nanocarrier formulations such as surfactant nanocellulose, ultra-lightweight porous materials, hydrogel, polyelectrolytes, and inorganic hybridizations has advanced to enable the construction of stimuli-responsive and specific recognition characteristics. Thus, an opportunity has emerged to develop a new generation of nanocellulose-based carriers that can modulate the drug conveyance for diverse drug characteristics. This review provides insights into selecting appropriate nanocellulose-based hybrid materials and the available modification routes to achieve satisfactory carrier performance and briefly discusses the essential criteria to achieve high-quality nanocellulose.

A double-network polysaccharide-based composite hydrogel for skin wound healing

Effective wound dressings are of great significance in preventing infections and promoting wound healing. However, most existing hydrogel dressings have an inadequacy in either mechanical performance, biological activities, or versatilities. Here we presented a double-network cross-linked polysaccharide-based hydrogel composed of collagen peptide-functionalized carboxymethyl chitosan (CS) and oxidized methacrylate sodium alginate (SA). The hydrogel possessed interconnected porous morphologies, suitable swelling ratios, excellent mechanical properties, and favorable biocompatibility. Meanwhile, the in vivo studies using a mouse full-thickness skin defect model showed that the double-network CS/SA hydrogel significantly accelerated wound healing by regulating the inflammatory process, promoting collagen deposition, and improving vascularization. Therefore, the functionalized double-network hydrogel should be a potential candidate as wound dressings.

Polyvinyl alcohol/chitosan composite hydrogels with sustained release of traditional Tibetan medicine for promoting chronic diabetic wound healing

The Tibetan eighteen flavor dangshen pills (TEP) are composed of 18 traditional Tibetan medicines, which are commonly used in the treatment of skin diseases in the Tibetan medical system. They have anti-inflammatory and analgesic effects, and healing properties. However, TEP contain large doses and have strong side effects and low bioavailability. To improve the utilization rate of TEP in skin treatment, we prepared TEP powder and then introduced it into polyvinyl alcohol/chitosan (PVA/CS) hydrogels to treat diabetic wounds by slowly releasing the active ingredients of TEP. In vitro studies showed that TEP-loaded hydrogels can effectively and continuously release the active ingredients of TEP and have antibacterial and antioxidant properties. In addition, the hydrogel system was not cytotoxic to L929 cells, and significantly promoted the proliferation of HUVECs. Moreover, when the TEP-loaded hydrogel was applied to diabetic wounds in rats, it reduced the inflammatory response and improved collagen deposition, which in turn promoted skin healing. Our results indicate that TEP-loaded hydrogels may be a new formulation for the application of traditional Tibetan medicines for the treatment of chronic wounds.

An injectable peptide hydrogel with excellent self-healing ability to continuously release salvianolic acid B for myocardial infarction

Drug-loaded hydrogels can improve blood supply and inhibit extracellular matrix degradation after myocardial infarction. However, due to the continual dynamic motion of cardiac tissue, the hydrogel structure cannot be reconstructed in time, causing accelerated degradation and drug burst release. Here, a novel, superior, self-healing elastin-mimic peptide hydrogel (EMH) was fabricated for the local delivery of salvianolic acid B (SaB). The self-healing ability of EMH is enhanced by SaB-loaded polydopamine nanoparticles (SaB-PDA). In vitro, the pre-hydrogel (SaB-PDA/pre-EMH) is endowed with excellent biocompatibility and a low viscosity, making it suitable for intramyocardial injection. Once injected into the myocardial infarction (MI) region, SaB-PDA/pre-EMH can form SaB-PDA/EMH with great mechanical strength under the action of upregulated transglutaminase (TGase) in heart tissue post-MI. The superior self-healing ability of SaB-PDA/EMH allows for an increase in retention time in the beating ventricular wall. Therefore, with long-term release of SaB, SaB-PDA/EMH can inhibit ventricular remodeling and promote angiogenesis for MI treatment.

Fabrication a controlled-release pesticide for improving UV-shielding properties and reducing toxicity via coating polydopamine

Controlled-release formulations (CRFs) have potential applications in modern agriculture, for it can not only prolong the duration of agrochemicals but also alleviate the adverse effect on non-target organism. In this study, we constructed pyraclostrobin@SiO₂@polydopamine microcapsule (Pyr@SiO₂@PDA MC). The resulting microcapsule is a near-rod shape (about 1.15 μm), which has a drug-loading efficiency of 55%. Fourier transform infrared (FTIR) and thermogravimetric analysis (TG) revealed the successful entrapment of the pesticide. The coating of polydopamine (PDA) endowing the microcapsule with superior UV-shielding properties than pyraclostrobin@SiO₂ microcapsule (Pyr@SiO₂ MC). Compared with pyraclostrobin emulsifiable concentrate (EC), the Pyr@SiO₂@PDA MC exhibited 9.07-, 5.50-, 4.93- and 4.16-fold higher fungicidal activity against Rice blast fungus (Pyricularia oryzae) at concentrations of 0.5, 1, 2 and 4 mg/L. Moreover, acute toxicity tests demonstrated that the sample on zebrafish with lower toxicity on the first day. These results showed that the obtained microcapsule may process broader application potential in agriculture.

Research Progress of Thermosensitive Hydrogel in Tumor Therapeutic

Compared with traditional tumor therapy strategies, hydrogel as a drug reservoir system can realize on-demand drug release and deep tissue penetration ability. It also exhibits great tumor-site retention to enhance the permeability and retention effect of tumor treatment. This can significantly overcome the drug's resistance and severe side effects. Inorganic/organic composite hydrogel has attracted wide attention due to its combined effects, enhancing therapeutic effects against various kinds of tumors. In situ injectable hydrogel can securely restrict the drugs in the lesion sites without leakage and guarantee better biosafety. Moreover, hydrogel possesses interconnected macropores which can provide enough space for nutrient transport, cellular activity, and cell-cell interactions. Thermal therapy is an effective strategy for tumor therapy due to its minimal invasiveness and high selectivity. Because the location temperature can be precisely controlled and helps avoid the risks of destroying the body's immune system and ablate normal cells, thermal therapy exhibits significant treatment outcomes. Nonetheless, when the cellular temperature reaches approximately 43 °C, it causes long-term cell inactivation. Based on these merits, thermosensitive hydrogel formulation with adaptive functions shows excellent efficacy, unlimited tissue penetration capacity, and few deleterious side effects. Furthermore, the thermosensitive hydrogel has unique physical properties under the external stimuli, which is the ideal drug delivery system for on-demand release in tumor treatment. This article will review the state of the thermosensitive hydrogel in clinic application for cancer therapy.

A platform for functionalization of cellulose, chitin/chitosan, alginate with polydopamine: A review on fundamentals and technical applications

Nature provides concepts and materials with interesting functionalities to be implemented in innovative and sustainable materials. In this review, it is illustrated how the combination of biological macromolecules, i.e. polydopamine and polysaccharides (cellulose, chitin/chitosan, alginate), enables to create functional materials with controlled properties. The mussel-adhesive properties rely on the secretion of proteins having 3,4-dihydroxyphenylalanine amino acid with catechol groups. Fundamental understanding on the biological functionality and interaction mechanisms of dopamine in the mussel foot plaque is presented in parallel with the development of synthetic analogues through extraction or chemical polymer synthesis. Subsequently, modification of cellulose, chitin/chitosan or alginate and their nanoscale structures with polydopamine is discussed for various technical applications, including bio- and nanocomposites, films, filtration or medical membranes, adhesives, aerogels, or hydrogels. The presence of polydopamine stretches far beyond surface adhesive properties, as it can be used as an intermediate to provide additional performance of hydrophobicity, self-healing, antimicrobial, photocatalytic, sensoric, adsorption, biocompatibility, conductivity, coloring or mechanical properties. The dopamine-based 'green' chemistry can be extended towards generalized catechol chemistry for modification of polysaccharides with tannic acid, caffeic acid or laccase-mediated catechol functionalization. Therefore, the modification of polysaccharides with polydopamine or catechol analogues provides a general platform for sustainable material functionalization.

Polydopamine-Ag composite surface guides HBMSCs adhesion and proliferation

Human bone marrow mesenchymal stem cells (HBMSCs) are regarded as an important resource in the field of maxillofacial bone regeneration because of their favorable properties when compared with other stem cells. Hence, finding suitable materials that could extend the application of HBMSCs has become an emerging medical topic and socioeconomic problem. In this work, polydopamine (PDA)-Ag surface was fabricated by PDA assisted photoreduction method, and the obtained PDA-Ag composite surface significantly promoted HBMSCs adhesion and proliferation. This effect is highly related to the amount of Ag nanoparticles (Ag NPs) present on the PDA surface. The behavior of HBMSCs on PDA-Ag surface could be spatially manipulated by controlling the distribution of Ag NPs on PDA surface (by controlling UV light). The general adhesion property allows the PDA-Ag surface to be fabricated on various substrates, making it a simple, general and controllable method for the fabrication of bioactive surface for HBMSCs.

One-step electrochemically induced counterion exchange to construct free-standing carboxylated cellulose nanofiber/metal composite hydrogels

The fabrication of polymeric composite hydrogel with hierarchical structure in a simple, controllable, and straightforward process poses great importance for manufacturing nanomaterials and subsequent applications. Herein, we report a one-step and template-free counterion exchange method to construct free-standing carboxylated cellulose nanofiber composite hydrogels. Metal ions were electrochemically and locally released from the electrode and chelated with carboxylated cellulose nanofibers, leading to the in-situ formation of composite hydrogels. The properties of composite hydrogels can be easily programmed by the type of electrode, current density, and electrodeposited suspension. Significantly, the composited hydrogels exhibited interconnected nanoporous structure, enhanced thermal degradation, improved mechanical strength and antibacterial activity. The results suggest great potential of anodic electrodeposition to fabricate nanofiber/metal composite hydrogels.

Mussel-inspired double cross-linked hydrogels with desirable mechanical properties, strong tissue-adhesiveness, self-healing properties and antibacterial properties

Developing multifunctional hydrogels with good mechanical properties, tissue-adhesiveness, self-healing properties and antioxidant, blood clotting and antibacterial properties is highly desirable for biomedical applications. In this study, a series of multifunctional chitosan-based double cross-linked hydrogels were prepared using a facile method based on quaternized chitosan (QCS) and polyacrylamide (PAM) using polydopamine (PDA) as a novel connecting bridge. Investigation on the content of dopamine (DA) and QCS revealed that the catechol-mediated interactions played an important role in the hydrogel properties. Results showed that the hydrogel exhibited the best mechanical properties when QCS = 12 wt% and DA = 0.4 wt%. Tensile and compressive strength was 13.3 kPa and 67.8 kPa, respectively, and the hydrogel presented strong and repeatable tissue-adhesiveness (27.2 kPa) to porcine skin, as well as good stretchability (1154%). At room temperature, the hydrogel exhibited high self-healing efficiency (90% after 2 h of healing). Antibacterial test results showed that the hydrogel killed 99.99% S. aureus and E. coli. Moreover, the vaccarin-loaded hydrogel exhibited a pH-responsive drug release profile with superior cytocompatibility compared to the pure hydrogel. In summary, this strategy combined double cross-linking and catechol-mediated chemistry to shed new light on the fabrication of novel multifunctional hydrogels with desirable mechanical properties, strong tissue adhesiveness and self-healing abilities.

Stimuli-responsive polydopamine-based smart materials

This review provides in-depth insight into the structural engineering of PDA-based materials to enhance their responsive feature and the use of them in construction of PDA-based stimuli-responsive smart materials.

Nanocellulose: Recent Fundamental Advances and Emerging Biological and Biomimicking Applications

In the effort toward sustainable advanced functional materials, nanocelluloses have attracted extensive recent attention. Nanocelluloses range from rod-like highly crystalline cellulose nanocrystals to longer and more entangled cellulose nanofibers, earlier denoted also as microfibrillated celluloses and bacterial cellulose. In recent years, they have spurred research toward a wide range of applications, ranging from nanocomposites, viscosity modifiers, films, barrier layers, fibers, structural color, gels, aerogels and foams, and energy applications, until filtering membranes, to name a few. Still, nanocelluloses continue to show surprisingly high challenges to master their interactions and tailorability to allow well-controlled assemblies for functional materials. Rather than trying to review the already extensive nanocellulose literature at large, here selected aspects of the recent progress are the focus. Water interactions, which are central for processing for the functional properties, are discussed first. Then advanced hybrid gels toward (multi)stimuli responses, shape-memory materials, self-healing, adhesion and gluing, biological scaffolding, and forensic applications are discussed. Finally, composite fibers are discussed, as well as nanocellulose as a strategy for improvement of photosynthesis-based chemicals production. In summary, selected perspectives toward new directions for sustainable high-tech functional materials science based on nanocelluloses are described.

Injectable Adhesive Self-Healing Multicross-Linked Double-Network Hydrogel Facilitates Full-Thickness Skin Wound Healing

The development of natural polymer-based hydrogels, combining outstanding injectability, self-healing, and tissue adhesion, with mechanical performance, able to facilitate full-thickness skin wound healing, remains challenging. We have developed an injectable micellar hydrogel (AF127/HA-ADH/OHA-Dop) with outstanding adhesive and self-healing properties able to accelerate full-thickness skin wound healing. Dopamine-functionalized oxidized hyaluronic acid (OHA-Dop), adipic acid dihydrazide-modified HA (HA-ADH), and aldehyde-terminated Pluronic F127 (AF127) were employed as polymer backbones. They were cross-linked in situ using Schiff base dynamic covalent bonds (AF127 micelle/HA-ADH network and HA-ADH/OHA-Dop network), hydrogen bonding, and π-π stacking interactions. The resulting multicross-linked double-network design forms a micellar hydrogel. The unique multicross-linked double-network structure endows the hydrogel with both improved injection abilities and mechanical performance while self-healing faster than single-network hydrogels. Inspired by mussel foot adhesive protein, OHA-Dop mimics the catechol groups seen in mussel proteins, endowing hydrogels with robust adhesion properties. We also demonstrate the potential of our hydrogels to accelerate full-thickness cutaneous wound closure and improve skin regeneration with reduced scarring. We anticipate that our hydrogel platform based on a novel multicross-linked double-network design will transform the future development of multifunctional wound dressings.

Construction of a Mesoporous Polydopamine@GO/Cellulose Nanofibril Composite Hydrogel with an Encapsulation Structure for Controllable Drug Release and Toxicity Shielding

The development of intelligent and multifunctional hydrogels having photothermal properties, good mechanical properties, sustained drug release abilities with low burst release, antibacterial properties, and biocompatibility is highly desirable in the biomaterial field. Herein, mesoporous polydopamine (MPDA) nanoparticles wrapped with graphene oxide (GO) were physically cross-linked in cellulose nanofibril (CNF) hydrogel to obtain a novel MPDA@GO/CNF composite hydrogel for controllable drug release. MPDA nanoparticles exhibited a high drug loading ratio (up to 35 wt %) for tetracycline hydrochloride (TH). GO was used to encapsulate MPDA nanoparticles for extending the drug release time and reinforcing the physical strength of the obtained hydrogel. The mechanical strength of the as-fabricated MPDA@GO/CNF composite hydrogel was five times greater compared to that of the pure CNF hydrogel. Drug release experiments demonstrated that burst release behavior was significantly reduced by adding MPDA@GO. The drug release time of the MPDA@GO/CNF composite hydrogel was 3 times and 7.2 times longer than that of the polydopamine/CNF hydrogel and pure CNF hydrogel, respectively. The sustained and controlled drug release behaviors of the composite hydrogel were highly dependent on the proportion of MPDA and GO. Moreover, the rate of drug release could be accelerated by near-infrared (NIR) light irradiation and pH value change. The drug release kinetics of the as-prepared composite hydrogel was well described by the Korsmeyer-Peppas model, and the drug release mechanism of TH from the composite hydrogel was anomalous transport. Importantly, this carefully designed MPDA@GO/CNF composite hydrogel showed good biocompatibility through an in vitro cytotoxicity test. In particular, the toxicity of GO was well shielded by the CNF hydrogel. Therefore, this novel MPDA@GO/CNF composite hydrogel with an encapsulation structure for controllable drug release and toxicity shielding of GO could be used as a very promising controlled drug delivery carrier, which may have potential applications for chemical and physical therapies.

Polydopamine-based nanomaterials and their potentials in advanced drug delivery and therapy

Polydopamine (PDA) has shown great potentials in biomedical fields due largely to its unique physicochemical properties, including high photothermal transfer efficiency, excellent drug binding capacity, versatile adhesion ability, sensitive pH responsibility and great biocompatibility and biodegradability. These properties confer PDA-based nanoparticles the potentials either as the drug carriers for advanced drug delivery or as the bioactive agents for photothermal therapy, imaging and biosensing. This review aims to provide a comprehensive understanding of PDA, its polymerization mechanisms and the potentials of PDA-based nano-systems in treating various diseases, including cancer, diabetes, inflammation, bacterial infection and Parkinson's disease. In addition, the concerns of PDA in biomedical use are also discussed.

Effects of a complex mixture prepared from agrimonia, houttuynia, licorice, peony, and phellodendron on human skin cells

Active ingredients derived from natural sources are widely utilized in many industries. Cosmetic active ingredients are largely derived from various plants. In this study, we examined whether a mixture of plant extracts obtained from agrimonia, houttuynia, licorice, peony, and phellodendron (hereafter AHLPP), which are well-known for their effects on skin, could affect skin barrier function, inflammation, and aging in human skin cells. We also determined whether AHLPP extracts sterilized using γ-irradiation (to avoid preservatives) retained their skin cell regulating activity. The AHLPP mixture could downregulate representative pro-inflammatory cytokines including IL 1-β and IL 7. Procollagen peptide synthesis was also increased by AHLPP treatment along with mRNA upregulation of barrier proteins such as filaggrin and desmoplakin. The AHLPP mixture showed an anti-aging effect by significantly upregulating telomerase activity in human keratinocytes. We further observed TERT upregulation and CDKN1B downregulation, implying a weakening of pro-aging signal transduction. Co-cultivation of a hydrogel polymer containing the AHLPP mixture with human skin cells showed an alteration in skin-significant genes such as FLG, which encodes filaggrin. Thus, the AHLPP mixture with or without γ-irradiation can be utilized for skin protection as it alters the expression of some significant genes in human skin cells.

Potential Applications of Nanomaterials and Technology for Diabetic Wound Healing

Diabetic wound shows delayed and incomplete healing processes, which in turn exposes patients to an environment with a high risk of infection. This article has summarized current developments of nanoparticles/hydrogels and nanotechnology used for promoting the wound healing process in either diabetic animal models or patients with diabetes mellitus. These nanoparticles/hydrogels promote diabetic wound healing by loading bioactive molecules (such as growth factors, genes, proteins/peptides, stem cells/exosomes, etc.) and non-bioactive substances (metal ions, oxygen, nitric oxide, etc.). Among them, smart hydrogels (a very promising method for loading many types of bioactive components) are currently favored by researchers. In addition, nanoparticles/hydrogels can be combined with some technology (including PTT, LBL self-assembly technique and 3D-printing technology) to treat diabetic wound repair. By reviewing the recent literatures, we also proposed new strategies for improving multifunctional treatment of diabetic wounds in the future.

EGFR-conjugated hydrogel accelerates wound healing on ulcer-induced burn wounds by targeting collagen and inflammatory cells using photoimmunomodulatory inhibition

In the present study, we fabricated an epidermal growth factor receptor (EGFR)-conjugated hydrogel to promote wound healing in cold restraint-induced gastric ulceration on burn wounds targeting collagen and inflammatory cells for the treatment of burns and gastric ulcers. Cytotoxicity and cell proliferation assays demonstrated good biocompatibility of hydrogel as a suitable extracellular matrix for targeted cells and support for regenerative cell growth. These findings were confirmed by staining methods. In vitro wound healing was confirmed cell migration in the targeted cells. The effect of the EGFR-H was investigated in cold restraint-induced gastric ulcers in rats, where the treatment was started immediately after ulcer induction. In the in vivo experiment, the EGFR-H demonstrated enhanced ulcer healing ability and less scarring compared to the hydrogel alone and controls. Thus, EGFR-H promotes healing of cold restraint-induced gastric ulcer via EGFR conjugated with a hydrogel. The present study demonstrates a novel pathway to fabricate hydrogels as suitable wound dressing biomaterials to improve deep partial thickness burn wound healing and prevent scar formation when aided by laser therapy.

Nanocellulose in Drug Delivery and Antimicrobially Active Materials

In recent years, nanocellulose (NC) has also attracted a great deal of attention in drug delivery systems due to its unique physical properties, specific surface area, low risk of cytotoxicity, and excellent biological properties. This review is focused on nanocellulose based systems acting as carriers to be used in drug or antimicrobial delivery by providing different but controlled and sustained release of drugs or antimicrobial agents, respectively, thus showing potential for different routes of applications and administration. Microorganisms are increasingly resistant to antibiotics, and because, generally, the used metal or metal oxide nanoparticles at some concentration have toxic effects, more research has focused on finding biocompatible antimicrobial agents that have been obtained from natural sources. Our review contains the latest research from the last five years that tested nanocellulose-based materials in the field of drug delivery and antimicrobial activity.

Bio-Applications of Multifunctional Melanin Nanoparticles: From Nanomedicine to Nanocosmetics

Bioinspired nanomaterials are ideal components for nanomedicine, by virtue of their expected biocompatibility or even complete lack of toxicity. Natural and artificial melanin-based nanoparticles (MNP), including polydopamine nanoparticles (PDA NP), excel for their extraordinary combination of additional optical, electronic, chemical, photophysical, and photochemical properties. Thanks to these features, melanin plays an important multifunctional role in the design of new platforms for nanomedicine where this material works not only as a mechanical support or scaffold, but as an active component for imaging, even multimodal, and simple or synergistic therapy. The number of examples of bio-applications of MNP increased dramatically in the last decade. Here, we review the most recent ones, focusing on the multiplicity of functions that melanin performs in theranostics platforms with increasing complexity. For the sake of clarity, we start analyzing briefly the main properties of melanin and its derivative as well as main natural sources and synthetic methods, moving to imaging application from mono-modal (fluorescence, photoacoustic, and magnetic resonance) to multi-modal, and then to mono-therapy (drug delivery, anti-oxidant, photothermal, and photodynamic), and finally to theranostics and synergistic therapies, including gene- and immuno- in combination to photothermal and photodynamic. Nanomedicine aims not only at the treatment of diseases, but also to their prevention, and melanin in nature performs a protective action, in the form of nanopigment, against UV-Vis radiations and oxidants. With these functions being at the border between nanomedicine and cosmetics nanotechnology, recently examples of applications of artificial MNP in cosmetics are increasing, paving the road to the birth of the new science of nanocosmetics. In the last part of this review, we summarize and discuss these important recent results that establish evidence of the interconnection between nanomedicine and cosmetics nanotechnology.

Plant-based nanocellulose: A review of routine and recent preparation methods with current progress in its applications as rheology modifier and 3D bioprinting

"Nanocellulose" have captivated the topical sphere of sturdily escalating market for sustainable materials. The review focuses on the comprehensive understanding of the distinct surface chemistry and functionalities pertaining to the renovation of macro-cellulose at nanodimensional scale to provide an intuition of their processing-structure-function prospective. The abundant availability, cost effectiveness and diverse properties associated with plant-based resources have great economical perspective for developing sustainable cellulose nanomaterials. Hence, emphasis has been given on nanocellulose types obtained from plant-based sources. An overarching goal is to provide the recent advancement in the preparation routes of nanocellulose. Considering the excellent shear thinning/thixotropic/gel-like behavior, the review provids an assemblage of publications specifically dealing with its application as rheology modifier with emphasis on its use as bioink for 3D bioprinting for various biomedical applications. Altogether, this review has been oriented in a way to collocate a collective data starting from the historical perspective of cellulose discovery to modern cellulosic chemistry and its renovation as nanocellulose with recent technological hype for broad spanning applications.

Polymeric-based microneedle arrays as potential platforms in the development of drugs delivery systems

BACKGROUND

Microscopic patches as quite promising platforms in transdermal drug delivery suffer from conventional injections. In other hand, a wide range of pharmacokinetics, ranging from fast oral administration to sustained drug delivery, can be implemented with the help of microneedle arrays (MNAs).

AIM OF REVIEW

Hence, in this paper, we overviewed different kinds of MNAs such as solid/coated, hollow, porous, hydrogel/swellable, and merged-tip geometry followed by introducing different types of material (silicon, glass, ceramics, dissolving and biodegradable polymers, and hydrogel) used for fabrication of MNAs. Afterwards, some conventional and brand-new simple and customizable MN mold fabrication techniques were surveyed. Polymeric MNAs have received a great deal of attention due to their potential biocompatibility and biodegradability in comparison to other materials. Therefore, we also covered different kinds of polymers such as hydrogel/swellable, dissolving and biodegradable analogues used for the development of MNAs as potential candidates in drug delivery systems (DDSs). Finally, we discussed different challenges and future perspectives in the aspect of MNAs-based drug delivery platforms.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review may provide guidelines for the rational design of polymeric MNAs-based DDSs for promising programmable drug release and enhanced therapeutic effect.

Recent Advances in Porous 3D Cellulose Aerogels for Tissue Engineering Applications: A Review

Current approaches in developing porous 3D scaffolds face various challenges, such as failure of mimicking extracellular matrix (ECM) native building blocks, non-sustainable scaffold fabrication techniques, and lack of functionality. Polysaccharides and proteins are sustainable, inexpensive, biodegradable, and biocompatible, with structural similarities to the ECM. As a result, 3D-structured cellulose (e.g., cellulose nanofibrils, nanocrystals and bacterial nanocellulose)-based aerogels with high porosity and interconnected pores are ideal materials for biomedical applications. Such 3D scaffolds can be prepared using a green, scalable, and cost-effective freeze-drying technique. The physicochemical, mechanical, and biological characteristics of the cellulose can be improved by incorporation of proteins and other polysaccharides. This review will focus on recent developments related to the cellulose-based 3D aerogels prepared by sustainable freeze-drying methods for tissue engineering applications. We will also provide an overview of the scaffold development criteria; parameters that influenced the aerogel production by freeze-drying; and in vitro and in vivo studies of the cellulose-based porous 3D aerogel scaffolds. These efforts could potentially help to expand the role of cellulose-based 3D scaffolds as next-generation biomaterials.

Research Progress and Development Demand of Nanocellulose Reinforced Polymer Composites

Nanocellulose is a type of nanomaterial with high strength, high specific surface area and high surface energy. Additionally, it is nontoxic, harmless, biocompatible and environmentally friendly and can be extracted from biomass resources. The surface groups of cellulose show high surface energy and binding activity on the nanoscale and can be modified by using various methods. Because nanocellulose has a high elastic modulus, rigidity and a low thermal expansion coefficient, it is an excellent material for polymer reinforcement. This paper summarizes the reinforcement mechanisms of nanocellulose polymer composites with a focus on the role of theoretical models in elucidating these mechanisms. Furthermore, the influence of various factors on the properties of nanocellulose reinforced polymer composites are discussed in combination with analyses and comparisons of specific research results in related fields. Finally, research focus and development directions for the design of high-performance nanocellulose reinforced polymer composites are proposed.

Eco-friendly nanocellulose and its biomedical applications: current status and future prospect

Cellulose is the earth's leading natural polymer. It is known for its properties like biocompatibility, high mechanical strength, cost-effectiveness and lightweight. Nanocellulose displays better properties as compared to the native cellulose fibre. The nanocellulose is very remunerative in the arenas of routine application especially in health care, food industry, sanitary products and many more. In the biomedical area, cellulose-based products are utilized in applications like wound healing, dental applications, drug delivery, antimicrobial material, etc. Nanocellulose biomaterials have been commercialised, representing the material of new generation. With the objective to comprehend the contribution of nanocellulose in the current status and future development in biomedical utilisations, the review is focused on cellulose, nanocellulose, types and sources of nanocellulose, its preparation, characteristics, constraints related to its composites through the analysis of certain scientific reports.

pH-triggered intracellular release of doxorubicin by a poly(glycidyl methacrylate)-based double-shell magnetic nanocarrier

Two core-double-shell pH-sensitive nanocarriers were fabricated using Fe₃O₄ as magnetic core, poly(glycidyl methacrylate-PEG) and salep dialdehyde as the first and the second shell, and doxorubicin as the hydrophobic anticancer drug. Two nanocarriers were different in the drug loading steps. The interaction between the first and the second shell assumed to be pH-sensitive via acetal cross linkages. The structure of nanocarriers, organic shell loading, magnetic responsibility, morphology, size, dispersibility, and drug loading content were investigated by IR, NMR, TG, VSM, XRD, DLS, HRTEM and UV-Vis analyses. The long-term drug release profiles of both nanocarriers showed that the drug loading before cross-linking between the first and second shell led to a more pH-sensitive nanocarrier exhibiting higher control on DOX release. Cellular toxicity assay (MTT) showed that DOX-free nanocarrier is biocompatible having cell viability greater than 80% for HEK-293 and MCF-7 cell lines. Besides, high cytotoxic effect observed for drug-loaded nanocarrier on MCF-7 cancer cells. Cellular uptake analysis showed that the nanocarrier is able to transport DOX into the cytoplasm and perinuclear regions of MCF-7 cells. In vitro hemolysis and coagulation assays demonstrated high blood compatibility of nanocarrier. The results also suggested that low concentration of nanocarrier have a great potential as a contrast agent in magnetic resonance imaging (MRI).

Multifunctional Tissue-Adhesive Cryogel Wound Dressing for Rapid Nonpressing Surface Hemorrhage and Wound Repair

Cryogels with tissue adhesion have great potential as wound dressings for rapid hemostasis for uncontrollable nonpressing surface hemorrhage and wound healing, but their use has not been reported previously. Herein, we designed a series of antibacterial and antioxidant tissue-adhesive cryogels based on quaternized chitosan (QCS) and polydopamine (PDA). These cryogels had good blood cell and platelet adhesion, enrichment, and activation properties for rapid nonpressing surface hemostasis and wound healing. The cryogels exhibited outstanding mechanical strength and easy removability, antioxidant activity, and NIR photothermal-enhanced antibacterial performance. The cryogels showed much better hemostasis than gauze and gelatin sponge in a standardized strip rat liver injury model, a standardized circular rabbit liver section model, and a pig skin laceration model. Furthermore, the excellent hemostatic performance of the QCS/PDA2.0 cryogel (containing 20 mg/mL QCS and 2.0 mg/mL PDA) for coagulopathic hemorrhages was confirmed in a standardized coagulation disorder rabbit circular liver section model. In addition, the QCS/PDA2.0 cryogel promoted rapid hemostasis in a deep noncompressible wound and a much better wound healing effect than a chitosan sponge and Tegaderm film in a full-thickness skin defect model. Overall, these multifunctional tissue-adhesive cryogels with excellent hemostatic performance and enhanced wound healing properties are suitable candidates for tissue-adhesive hemostat and wound healing dressings.

Cellulose Nanofibrils-based Hydrogels for Biomedical Applications: Progresses and Challenges

Background:

Cellulose Nanofibrils (CNFs) are natural nanomaterials with nanometer dimensions. Compared with ordinary cellulose, CNFs own good mechanical properties, large specific surface areas, high Young's modulus, strong hydrophilicity and other distinguishing characteristics, which make them widely used in many fields. This review aims to introduce the preparation of CNFs-based hydrogels and their recent biomedical application advances.

Methods:

By searching the recent literatures, we have summarized the preparation methods of CNFs, including mechanical methods and chemical mechanical methods, and also introduced the fabrication methods of CNFs-based hydrogels, including CNFs cross-linked with metal ion and with polymers. In addition, we have summarized the biomedical applications of CNFs-based hydrogels, including scaffold materials and wound dressings.

Results:

CNFs-based hydrogels are new types of materials that are non-toxic and display a certain mechanical strength. In the tissue scaffold application, they can provide a micro-environment for the damaged tissue to repair and regenerate it. In wound dressing applications, it can fit the wound surface and protect the wound from the external environment, thereby effectively promoting the healing of skin tissue.

Conclusion:

By summarizing the preparation and application of CNFs-based hydrogels, we have analyzed and forecasted their development trends. At present, the research of CNFs-based hydrogels is still in the laboratory stage. It needs further exploration to be applied in practice. The development of medical hydrogels with high mechanical properties and biocompatibility still poses significant challenges.

Melanin and Melanin-Like Hybrid Materials in Regenerative Medicine

Melanins are a group of dark insoluble pigments found widespread in nature. In mammals, the brown-black eumelanins and the reddish-yellow pheomelanins are the main determinants of skin, hair, and eye pigmentation and play a significant role in photoprotection as well as in many biological functions ensuring homeostasis. Due to their broad-spectrum light absorption, radical scavenging, electric conductivity, and paramagnetic behavior, eumelanins are widely studied in the biomedical field. The continuing advancements in the development of biomimetic design strategies offer novel opportunities toward specifically engineered multifunctional biomaterials for regenerative medicine. Melanin and melanin-like coatings have been shown to increase cell attachment and proliferation on different substrates and to promote and ameliorate skin, bone, and nerve defect healing in several in vivo models. Herein, the state of the art and future perspectives of melanins as promising bioinspired platforms for natural regeneration processes are highlighted and discussed.

Marine Algae Polysaccharides as Basis for Wound Dressings, Drug Delivery, and Tissue Engineering: A Review

The present review considers the physicochemical and biological properties of polysaccharides (PS) from brown, red, and green algae (alginates, fucoidans, carrageenans, and ulvans) used in the latest technologies of regenerative medicine (tissue engineering, modulation of the drug delivery system, and the design of wound dressing materials). Information on various types of modern biodegradable and biocompatible PS-based wound dressings (membranes, foams, hydrogels, nanofibers, and sponges) is provided; the results of experimental and clinical trials of some dressing materials in the treatment of wounds of various origins are analyzed. Special attention is paid to the ability of PS to form hydrogels, as hydrogel dressings meet the basic requirements set out for a perfect wound dressing. The current trends in the development of new-generation PS-based materials for designing drug delivery systems and various tissue-engineering scaffolds, which makes it possible to create human-specific tissues and develop target-oriented and personalized regenerative medicine products, are also discussed.

Production of Cellulose Nanofibers from Olive Tree Harvest—A Residue with Wide Applications

With the aim of identifying new sources to produce cellulose nanofibers, olive tree pruning biomass (OTPB) was proposed for valorization as a sustainable source of cellulose. OTPB was subjected to a soda pulping process for cellulose purification and to facilitate the delamination of the fiber in the nanofibrillation process. Unbleached and bleached pulp were used to study the effect of lignin in the production of cellulose nanofibers through different pretreatments (mechanical and TEMPO-mediated oxidation). High-pressure homogenization was used as the nanofibrillation treatment. It was observed that for mechanical pretreatment, the presence of lignin in the fiber produces a greater fibrillation, resulting in a smaller width than that achieved with bleached fiber. In the case of TEMPO-mediated oxidation, the cellulose nanofiber characteristics show that the presence of lignin has an adverse effect on fiber oxidation, resulting in lower nanofibrillation. It was observed that the crystallinity of the nanofibers is lower than that of the original fiber, especially for unbleached nanofibers. The residual lignin content resulted in a greater thermal stability of the cellulose nanofibers, especially for those obtained by TEMPO-mediated oxidation. The characteristics of the cellulose nanofibers obtained in this work identify a gateway to many possibilities for reinforcement agents in paper suspension and polymeric matrices.

Recent advances in celluloses and their hybrids for stimuli-responsive drug delivery

The limitations of existing drug delivery systems (DDS) such as non-specific bio-distribution and poor selectivity have led to the exploration of a variety of carrier platforms to facilitate highly desirable and efficient drug delivery. Stimuli-responsive DDS are one of the most versatile and innovative approach to steer the compounds to the intended sites by exploiting their responsiveness to a range of various triggers. Preparation of stimuli-responsive DDS using celluloses and their derivatives offer a remarkable advantage over conventional polymer materials. In this review, we highlight on state-of-art progress in developing cellulose/cellulose hybrid stimuli-responsive DDS, which covers the preparation techniques, physicochemical properties, basic principles and, mechanisms of stimuli effect on drug release from various types of cellulose based carriers, through recent innovative investigations. Attention has been paid to endogenous stimuli (pH, temperature, redox gradient and ionic-strength) responsive DDS and exogenous stimuli (light, magnetic field and electric field) responsive DDS, where the cellulose-based materials have been extensively employed. Furthermore, the current challenges and future prospects of these DDS are also discussed at the end.

Nanomedicine for Gene Delivery for the Treatment of Cardiovascular Diseases

Background:

Myocardial infarction (MI) is the most severe ischemic heart disease and di-rectly leads to heart failure till death. Target molecules have been identified in the event of MI including increasing angiogenesis, promoting cardiomyocyte survival, improving heart function and restraining inflammation and myocyte activation and subsequent fibrosis. All of which are substantial in cardiomy-ocyte protection and preservation of cardiac function.

Methodology:

To modulate target molecule expression, virus and non-virus-mediated gene transfer have been investigated. Despite successful in animal models of MI, virus-mediated gene transfer is hampered by poor targeting efficiency, low packaging capacity for large DNA sequences, immunogenicity induced by virus and random integration into the human genome.

Discussion:

Nanoparticles could be synthesized and equipped on purpose for large-scale production. They are relatively small in size and do not incorporate into the genome. They could carry DNA and drug within the same transfer. All of these properties make them an alternative strategy for gene transfer. In the review, we first introduce the pathological progression of MI. After concise discussion on the current status of virus-mediated gene therapy in treating MI, we overview the history and development of nanoparticle-based gene delivery system. We point out the limitations and future perspective in the field of nanoparticle vehicle.

Conclusion:

Ultimately, we hope that this review could help to better understand how far we are with nanoparticle-facilitated gene transfer strategy and what obstacles we need to solve for utilization of na-nomedicine in the treatment of MI.