Nanoparticle-hydrogel superstructures for biomedical applications

Magnetically responsive micro-clustered calcium phosphate-reinforced cell-laden microbead sodium alginate hydrogel for accelerated osteogenic tissue regeneration

The rising prevalence of bone injuries has increased the demand for minimally invasive treatments. Microbead hydrogels, renowned for cell encapsulation, provide a versatile substrate for bone tissue regeneration. They deliver bioactive agents, support cell growth, and promote osteogenesis, aiding bone repair and regeneration. In this study, we synthesized superparamagnetic iron oxide nanoparticles (Sp) coated with a calcium phosphate layer (m-Sp), achieving a distinctive flower-like micro-cluster morphology. Subsequently, sodium alginate (SA) microbead hydrogels containing m-Sp (McSa@m-Sp) were fabricated using a dropping gelation strategy. McSa@m-Sp is magnetically targetable, enhance cross-linking, control degradation rates, and provide strong antibacterial activity. Encapsulation studies with MC3T3-E1 cells revealed enhanced viability and proliferation. These studies also indicated significantly elevated alkaline phosphatase (ALP) activity and mineralization in MC3T3-E1 cells, as confirmed by Alizarin Red S (ARS) and Von Kossa staining, along with increased collagen production within the McSa@m-Sp microbead hydrogels. Immunocytochemistry (ICC) and gene expression studies supported the osteoinductive potential of McSa@m-Sp, showing increased expression of osteogenic markers including RUNX-2, collagen-I, osteopontin, and osteocalcin. Thus, McSa@m-Sp microbead hydrogels offer a promising strategy for multifunctional scaffolds in bone tissue engineering.

Erlotinib and curcumin-loaded nanoparticles embedded in thermosensitive chitosan hydrogels for enhanced treatment of head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) remain a major oncological challenge with significant morbidity and mortality rates. Erlotinib (Er) and Curcumin (Cm) are potential therapeutic agents for HNSCC, yet they are hindered by poor solubility and bioavailability. This study explored the optimization of poly(lactic-co-glycolic acid) nanoparticles co-loaded with Er and Cm (Er/Cm-NP), prepared via a D-optimal response surface design-guided nanoprecipitation process. The optimized formulation, optEr/Cm-NP, was then incorporated into chitosan/β-glycerophosphate hydrogels (optEr/Cm-NP-HG) to create an injectable intratumoral (IT) nanocomposite hydrogel (HG) delivery system. Physicochemical properties of the formulations, including gelation time, injectability, mechanical strength and drug release profiles were assessed alongside hemolytic activity. Compared to optEr/Cm-NP alone, the NP-loaded HG formulation exhibited a more pronounced modulation effect, enabling sustained and controlled drug release. The cytotoxicity of the developed formulations was evaluated using the FaDu HNSCC cancer cell line. Both optEr/Cm-NP and optEr/Cm-NP-HG21 displayed enhanced cytotoxicity compared to free drugs. Confocal laser microscopy and flow cytometry confirmed superior cellular uptake of Er and Cm when delivered via NPs or NP-loaded HG. Furthermore, a significant increase in apoptotic cell death upon treatment with optEr/Cm-NP was observed, highlighting its potential for HNSCC therapy. In vivo studies conducted on a xenograft HNSCC mouse model revealed the significant capacity of the intratumorally-injected optEr/Cm-NP-HG21 formulation to retard the tumor growth. Conclusively, the results presented herein report the successful development of a nanocomposite HG system incorporating NPs co-loaded with Er and Cm that could be efficiently utilized in the treatment of HNSCC.

Innovative hydrogel-based therapies for ischemia-reperfusion injury： bridging the gap between pathophysiology and treatment

Ischemia-reperfusion injury (IRI) commonly occurs in clinical settings, particularly in medical practices such as organ transplantation, cardiopulmonary resuscitation, and recovery from acute trauma, posing substantial challenges in clinical therapies. Current systemic therapies for IRI are limited by poor drug targeting, short efficacy, and significant side effects. Owing to their exceptional biocompatibility, biodegradability, excellent mechanical properties, targeting capabilities, controlled release potential, and properties mimicking the extracellular matrix (ECM), hydrogels not only serve as superior platforms for therapeutic substance delivery and retention, but also facilitate bioenvironment cultivation and cell recruitment, demonstrating significant potential in IRI treatment. This review explores the pathological processes of IRI and discusses the roles and therapeutic outcomes of various hydrogel systems. By categorizing hydrogel systems into depots delivering therapeutic agents, scaffolds encapsulating mesenchymal stem cells (MSCs), and ECM-mimicking hydrogels, this article emphasizes the selection of polymers and therapeutic substances, and details special crosslinking mechanisms and physicochemical properties, as well as summarizes the application of hydrogel systems for IRI treatment. Furthermore, it evaluates the limitations of current hydrogel treatments and suggests directions for future clinical applications.

Regenerative medicine: Hydrogels and mesoporous silica nanoparticles

Hydrogels, that are crosslinked polymer networks, can absorb huge quantities of water and/or biological fluids. Their physical properties, such as elasticity and soft tissue, together with their biocompatibility and biodegradability, closely resemble living tissues. The versatility of hydrogels has fuelled their application in various fields, such as agriculture, biomaterials, the food industry, drug delivery, tissue engineering, and regenerative medicine. Their combination with nanoparticles, specifically with Mesoporous Silica Nanoparticles (MSNs), have elevated these composites to the next level, since MSNs could improve the hydrogel mechanical properties, their ability to encapsulate and controlled release great amounts of different therapeutic agents, and their responsiveness to a variety of external and internal stimuli. In this review, the main features of both MSNs and hydrogels are introduced, followed by the discussion of different hydrogels-MSNs structures and an overview of their use in different applications, such as drug delivery technologies and tissue engineering.

Photothermal enhanced antibacterial chitosan-based polydopamine composite hydrogel for hemostasis and burn wound repairing

Bleeding and bacterial infection are common problems associated with wound treatment, while effective blood clotting and vessel regeneration promotion are the primary considerations to design the wound dressing materials. This research presents a chitosan-based hydrogel with grafted quaternary ammonium and polyphosphate (QCSP hydrogel) as the antibacterial hemostatic dressing to achieve burn wound treatment. The tissue adhesion of the hydrogel sealed the blood flow and the polyphosphate grafted to the chitosan promoted the activation of coagulation factor V to enhance the hemostasis. At the same time, the grafted quaternary ammonium enhanced the antibacterial ability of the biodegradable hydrogel wound dressing. In addition, the polydopamine as a photothermal agent was composited into the hydrogel to enhance the antibacterial and reactive oxygen scavenging performance. The in vivo hemostasis experiment proved the polyphosphate enhanced the coagulation property. Moreover, this photothermal property of the composite hydrogel enhanced the burn wound repairing rate combined with the NIR stimulus. As a result, this hydrogel could have potential application in clinic as dressing material for hemostasis and infection prone would repairing.

Alginate-based hydrogels mediated biomedical applications: A review

With the development in the field of biomaterials, research on alternative biocompatible materials has been initiated, and alginate in polysaccharides has become one of the research hotspots due to its advantages of biocompatibility, biodegradability and low cost. In recent years, with the further understanding of microscopic molecular structure and properties of alginate, various physicochemical methods of cross-linking strategies, as well as organic and inorganic materials, have led to the development of different properties of alginate hydrogels for greatly expanded applications. In view of the potential application prospects of alginate-based hydrogels, this paper reviews the properties and preparation of alginate-based hydrogels and their major achievements in delivery carrier, dressings, tissue engineering and other applications are also summarized. In addition, the combination of alginate-based hydrogel and new technology such as 3D printing are also involved, which will contribute to further research and exploration.

Smart Nanocomposite Hydrogels as Next-Generation Therapeutic and Diagnostic Solutions

Stimuli-responsive nanocomposite gels combine the unique properties of hydrogels with those of nanoparticles, thus avoiding the suboptimal results of single components and creating versatile, multi-functional platforms for therapeutic and diagnostic applications. These hybrid materials are engineered to respond to various internal and external stimuli, such as temperature, pH, light, magnetic fields, and enzymatic activity, allowing precise control over drug release, tissue regeneration, and biosensing. Their responsiveness to environmental cues permits personalized medicine approaches, providing dynamic control over therapeutic interventions and real-time diagnostic capabilities. This review explores recent advances in stimuli-responsive hybrid gels' synthesis and application, including drug delivery, tissue engineering, and diagnostics. Overall, these platforms have significant clinical potential, and future research is expected to lead to unique solutions to address unmet medical needs.

Comprehensive insights into mechanism of nanotoxicity, assessment methods and regulatory challenges of nanomedicines

Nanomedicine has the potential to transform healthcare by offering targeted therapies, precise diagnostics, and enhanced drug delivery systems. The National Institutes of Health has coined the term "nanomedicine" to describe the use of nanotechnology in biological system monitoring, control, diagnosis, and treatment. Nanomedicine continues to receive increasing interest for the rationalized delivery of therapeutics and pharmaceutical agents to achieve the required response while reducing its side effects. However, as nanotechnology continues to advance, concerns about its potential toxicological effects have also grown. This review explores the current state of nanomedicine, focusing on the types of nanoparticles used and their associated properties that contribute to nanotoxicity. It examines the mechanisms through which nanoparticles exert toxicity, encompassing various cellular and molecular interactions. Furthermore, it discusses the assessment methods employed to evaluate nanotoxicity, encompassing in-vitro and in-vivo models, as well as emerging techniques. The review also addresses the regulatory issues surrounding nanotoxicology, highlighting the challenges in developing standardized guidelines and ensuring the secure translation of nanomedicine into clinical settings. It also explores into the challenges and ethical issues associated with nanotoxicology, as understanding the safety profile of nanoparticles is essential for their effective translation into therapeutic applications.

Development of dual-crosslinked Pluronic F127/Chitosan injectable hydrogels incorporating graphene nanosystems for breast cancer photothermal therapy and antibacterial applications

Nanomaterials with responsiveness to near-infrared light can mediate the photoablation of cancer cells with an exceptional spatio-temporal resolution. However, the therapeutic outcome of this modality is limited by the nanostructures' poor tumor uptake. To address this bottleneck, it is appealing to develop injectable in situ forming hydrogels due to their capacity to perform a tumor-confined delivery of the nanomaterials with minimal off-target leakage. In particular, injectable in situ forming hydrogels based on Pluronic F127 have been emerging due to their FDA-approval status, biocompatibility, and thermosensitive sol-gel transition. Nevertheless, the application of Pluronic F127 hydrogels has been limited due to their fast dissociation in aqueous media. Such limitation may be addressed by combining the thermoresponsive sol-gel transition of Pluronic F127 with other polymers with crosslinking capabilities. In this work, a novel dual-crosslinked injectable in situ forming hydrogel based on Pluronic F127 (thermosensitive gelation) and Chitosan (ionotropic gelation in the presence of NaHCO3), loaded with Dopamine-reduced graphene oxide (DOPA-rGO; photothermal nanoagent), was developed for application in breast cancer photothermal therapy. The dual-crosslinked hydrogel incorporating DOPA-rGO showed a good injectability (through 21 G needles), in situ gelation capacity and cytocompatibility (viability > 73 %). As importantly, the dual-crosslinking improved the hydrogel's porosity and prevented its premature degradation. After irradiation with near-infrared light, the dual-crosslinked hydrogel incorporating DOPA-rGO produced a photothermal heating (ΔT ≈ 22 °C) that reduced the breast cancer cells' viability to just 32 %. In addition, this formulation also demonstrated a good antibacterial activity by reducing the viability of S. aureus and E. coli to 24 and 33 %, respectively. Overall, the dual-crosslinked hydrogel incorporating DOPA-rGO is a promising macroscale technology for breast cancer photothermal therapy and antimicrobial applications.

Cutting-Edge Hydrogel Technologies in Tissue Engineering and Biosensing: An Updated Review

Hydrogels, known for their unique ability to retain large amounts of water, have emerged as pivotal materials in both tissue engineering and biosensing applications. This review provides an updated and comprehensive examination of cutting-edge hydrogel technologies and their multifaceted roles in these fields. Initially, the chemical composition and intrinsic properties of both natural and synthetic hydrogels are discussed, highlighting their biocompatibility and biodegradability. The manuscript then probes into innovative scaffold designs and fabrication techniques such as 3D printing, electrospinning, and self-assembly methods, emphasizing their applications in regenerating bone, cartilage, skin, and neural tissues. In the realm of biosensing, hydrogels' responsive nature is explored through their integration into optical, electrochemical, and piezoelectric sensors. These sensors are instrumental in medical diagnostics for glucose monitoring, pathogen detection, and biomarker identification, as well as in environmental and industrial applications like pollution and food quality monitoring. Furthermore, the review explores cross-disciplinary innovations, including the use of hydrogels in wearable devices, and hybrid systems, and their potential in personalized medicine. By addressing current challenges and future directions, this review aims to underscore the transformative impact of hydrogel technologies in advancing healthcare and industrial practices, thereby providing a vital resource for researchers and practitioners in the field.

Liposomal nano-encapsulation of bFGF combined with injectable BSA hydrogel for efficient burn wound healing

Rapid and scar-free healing of burn wounds is an urgent clinical issue. Basic fibroblast growth factor (bFGF) has been proven to promote the healing of burn wounds by accelerating ECM remodeling and angiogenesis. However, exudates from burn wounds can accelerate bFGF degradation, thereby affecting its bioactivity. This study proposes an effective protection strategy for bFGF that involves encapsulating bFGF in nanoliposomes (bFGF-NLip) and then incorporating bFGF-NLip into a bovine serum albumin (BSA) hydrogel. This hybrid hydrogel system (bFGF-NLip@B) could maintain the activity of bFGF, achieve sustained release, and allow phospholipids and cholesterol to penetrate the skin, thereby enabling bFGF to function in the dermis. The experimental results showed that the hydrogel was injectable with good mechanical properties and biocompatibility. In a mouse scald wound model, owing to the sustained release of bFGF and skin permeation function of the nanoliposomes, the hydrogel promoted granulation formation, collagen deposition, vascular regeneration, and re-epithelialisation, ultimately accelerating wound healing. In addition, the hydrogel effectively inhibited scar formation. This system provides novel insights into the delivery of bFGF and scar-free healing of burn wounds.

Bilayer hydrogel with a protective film and a regenerative hydrogel for effective diabetic wound treatment

Diabetic foot ulcers (DFUs) are one of the most serious complications of diabetes, often leading to necrosis and amputation. DFU is caused by the intricate diabetic microenvironment, including ischemia, hypoxia, hyperinflammation, reduced angiogenesis, and persistent infection. Traditional wound dressings made of single or mixed materials often struggle to meet all the requirements for effective diabetic wound healing. In contrast, multilayer dressings comprising more than single layers have the potential to address these challenges by combining their diverse chemical and physical properties. In this study, we developed a bilayer hydrogel comprising a GelMA-ALG-nano-ZnO protective film and a COL1-PRP regenerative hydrogel for facilitating diabetic wound healing. We demonstrated the protective properties against bacterial infection of the protective film, while highlighting the regenerative potential of the COL1-PRP hydrogel in promoting fibroblast and MUVEC migration, extracellular matrix secretion and deposition, and angiogenesis. Importantly, the bilayer hydrogel exhibited superior efficacy in promoting full-thickness wound healing in a diabetic rat model compared to its single-layer hydrogel counterparts. This multi-layer approach offers a promising strategy for addressing the complexities of diabetic foot treatment and improving clinical outcomes.

Polyphenol-hyaluronic acid-based hydrogel remodels the wound microenvironment and eliminates bacterial infection for accelerating wound healing

The wound microenvironment, often characterized by alkaline pH and severe hypoxia, presents significant challenges to the healing of bacterial-infected wounds. While considerable research has focused on improving wound healing through effective bacterial elimination using advanced therapeutic approaches, the importance of regulating the wound microenvironment has received less emphasis. In this work, we developed a biocompatible hydrogel, HTFC, by incorporating CaO2 nanoparticles (CaO2 NPs) into a gel formed by tannic acid (TA), hyaluronic acid (HA), and Fe3+. The HA and TA in HTFC hydrogel help to create a slightly acidic microenvironment, facilitating the decomposition of CaO2 NPs to release H2O2 for chemodynamic therapy (CDT). The reduction properties of TA promote the recycling of Fe3+/Fe2+, enhancing CDT efficacy and partially converting H2O2 to O2, thereby alleviating hypoxia. Additionally, FeIIITA complexes in HTFC enhance CDT through photothermal therapy (PTT)-induced improvement of the Fenton reaction. This multifunctional hydrogel, with its synergistic effects of PTT and CDT, along with its ability to remodel the wound microenvironment from hypoxic and alkaline to normoxic and acidic, accelerates the bacterial-infected wound healing process.

Development and Validation of a Simple UV-HPLC Method to Quantify the Memantine Drug Used in Alzheimer's Treatment

Memantine, a non-competitive NMDA receptor antagonist, is used to treat Alzheimer's disease. Therefore, loading memantine in nanoparticles (NPs) could be an essential tool to improve the treatment effectiveness while reducing drug toxicity. Even though some approaches have been described to quantify memantine, none reported optimized methods using high-performance liquid chromatography resorting to ultraviolet detection (UV-HPLC) to determine encapsulation in NPs. The present research developed a HPLC method using pre-column derivatization for quantitatively analyzing memantine hydrochloride in NPs. Memantine was derivatized using 9-fluorenylmethyl chloroformate (FMOC). The developed method was fully validated regarding suitability, specificity, linearity, sensitivity, precision, accuracy, and robustness according to the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines. The retention time of memantine was 11.393 ± 0.003 min, with a mean recovery of 92.9 ± 3.7%. The new chromatographic method was validated and found to respond linearly over 5-140 μg/mL, with a high coefficient of determination. Intraday precision lay between 3.6% and 4.6%, and interday precision between 4.2% and 9.3%. The stability of memantine was also tested at 4 °C and -20 °C, and no signs of decay were found for up to 6 months. The new method was properly validated and proved simple, sensitive, specific, accurate, and precise for determining memantine encapsulation efficiency in lipid NPs. Greenness was evaluated, presenting a final score of 0.45. In the future, this methodology could also be applied to quantify memantine in different nanoformulations.

Sodium alginate-based high conductive, ultra-stretchable hydrogel fibers for electrolytes of flexible solid-state supercapacitors

The flexibility and safety of energy storage systems are crucial, and hydrogels as one of the most promising candidates for solid-state electrolytes. We present a conductive hydrogel based on sodium alginate that exhibits ultra-stretchable (4200 %) and high conductivity (16.3 S m-1). The mechanical properties of the conductive hydrogel are achieved by optimizing the topology of the sodium alginate and harnessing the synergistic effect of non-covalent interaction among different components. And a conductive structure within hydrogels was successfully established through the synergistic combination of ion and metal nanoparticles. The flexible supercapacitor (FSC) with conductive hydrogel as solid electrolytes demonstrated an area-specific capacitance of up to 274.28 mF cm-2 at a current density of 1 mA cm-2. And the energy density of the FSC is as high as 187 μWh cm-2 at a power density of 1.2 mW cm-2. The voltage range of the FSC is also extended to 1.4 V. The FSC also exhibited exceptional flexibility and stability, including insensitivity to bending angles and remarkable cycle durability (82.4 % after 10,000 cycles). The study presents a novel design for the development of solid-state electrolytes, with the aim of creating a new generation of FSC that exhibit superior safety and high energy density.

Nanomaterial-integrated injectable hydrogels for craniofacial bone reconstruction

The complex anatomy and biology of craniofacial bones pose difficulties in their effective and precise reconstruction. Injectable hydrogels (IHs) with water-swollen networks are emerging as a shape-adaptive alternative for noninvasively rebuilding craniofacial bones. The advent of versatile nanomaterials (NMs) customizes IHs with strengthened mechanical properties and therapeutically favorable performance, presenting excellent contenders over traditional substitutes. Structurally, NM-reinforced IHs are energy dissipative and covalently crosslinked, providing the mechanics necessary to support craniofacial structures and physiological functions. Biofunctionally, incorporating unique NMs into IH expands a plethora of biological activities, including immunomodulatory, osteogenic, angiogenic, and antibacterial effects, further favoring controllable dynamic tissue regeneration. Mechanistically, NM-engineered IHs optimize the physical traits to direct cell responses, regulate intracellular signaling pathways, and control the release of biomolecules, collectively bestowing structure-induced features and multifunctionality. By encompassing state-of-the-art advances in NM-integrated IHs, this review offers a foundation for future clinical translation of craniofacial bone reconstruction.

Hydrogels: a promising therapeutic platform for inflammatory skin diseases treatment

Inflammatory skin diseases, such as psoriasis and atopic dermatitis, pose significant health challenges due to their long-lasting nature, potential for serious complications, and significant health risks, which requires treatments that are both effective and exhibit minimal side effects. Hydrogels offer an innovative solution due to their biocompatibility, tunability, controlled drug delivery capabilities, enhanced treatment adherence and minimized side effects risk. This review explores the mechanisms that guide the design of hydrogel therapeutic platforms from multiple perspectives, focusing on the components of hydrogels, their adjustable physical and chemical properties, and their interactions with cells and drugs to underscore their clinical potential. We also examine various therapeutic agents for psoriasis and atopic dermatitis that can be integrated into hydrogels, including traditional drugs, novel compounds targeting oxidative stress, small molecule drugs, biologics, and emerging therapies, offering insights into their mechanisms and advantages. Additionally, we review clinical trial data to evaluate the effectiveness and safety of hydrogel-based treatments in managing psoriasis and atopic dermatitis under complex disease conditions. Lastly, we discuss the current challenges and future opportunities for hydrogel therapeutics in treating psoriasis and atopic dermatitis, such as improving skin barrier penetration and developing multifunctional hydrogels, and highlight emerging opportunities to enhance long-term safety and stability.

In Situ-Forming, Bioorthogonally Cross-linked, Nanocluster-Reinforced Hydrogel for the Regeneration of Corneal Defects

Corneal defects can lead to stromal scarring and vision loss, which is currently only treatable with a cadaveric corneal transplant. Although in situ-forming hydrogels have been shown to foster regeneration of the cornea in the setting of stromal defects, the cross-linking, biomechanical, and compositional parameters that optimize healing have not yet been established. This, Corneal defects are also almost universally inflamed, and their rapid closure without fibrosis are critical to preserving vision. Here, an in situ forming, bioorthogonally cross-linked, nanocluster (NC)-reinforced collagen and hyaluronic acid hydrogel (NCColHA hydrogel) with enhanced structural integrity and both pro-regenerative and anti-inflammatory effects was developed and tested within a corneal defect model in vivo. The NCs serve as bioorthogonal nanocross-linkers, providing higher cross-linking density than polymer-based alternatives. The NCs also serve as delivery vehicles for prednisolone (PRD) and the hepatocyte growth factor (HGF). NCColHA hydrogels rapidly gel within a few minutes upon administration and exhibit robust rheological properties, excellent transparency, and negligible swelling/deswelling behavior. The hydrogel's biocompatibility and capacity to support cell growth were assessed using primary human corneal epithelial cells. Re-epithelialization on the NCColHA hydrogel was clearly observed in rabbit eyes, both ex vivo and in vivo, with expression of normal epithelial biomarkers, including CD44, CK12, CK14, α-SMA, Tuj-1, and ZO-1, and stratified, multilayered morphology. The applied hydrogel maintained its structural integrity for at least 14 days and remodeled into a transparent stroma by 56 days.

In Situ Hydrogel with Immobilized Mn-Porphyrin for Reactive Oxygen Species Scavenging, Oxygen Generation, and Risedronate Delivery in Bone Defect Treatment

We propose a hydrogel immobilized with manganese porphyrin (MnP), a biomimetic superoxide dismutase (SOD), and catalase (CAT) to modulate reactive oxygen species (ROS) and hypoxia that impede the repair of large bone defects. Our hydrogel synthesis involved thiolated chitosan and polyethylene glycol-maleimide conjugated with MnPs (MnP-PEG-MAL), which enabled in situ gelation via a click reaction. Through optimization, a hydrogel with mechanical properties and catalytic effects favorable for bone repair was selected. Additionally, the hydrogel was incorporated with risedronate to induce synergistic effects of ROS scavenging, O2 generation, and sustained drug release. In vitro studies demonstrated enhanced proliferation and differentiation of MG-63 cells and suppressed proliferation and differentiation of RAW 264.7 cells in ROS-rich environments. In vivo evaluation of a calvarial bone defect model revealed that this multifunctional hydrogel facilitated significant bone regeneration. Therefore, the hydrogel proposed in this study is a promising strategy for addressing complex wound environments and promoting effective bone healing.

Iron(III) cross-linked hydrogels based on Alteromonas macleodii Mo 169 exopolysaccharide

Recently, polysaccharide-based hydrogels crosslinked with the trivalent iron cation have attracted interest due to their remarkable properties that include high mechanical stability, stimuli-responsiveness, and enhanced absorptivity. In this study, a Fe3+ crosslinked hydrogel was prepared using the biocompatible extracellular polysaccharide (EPS) secreted by the marine bacterium Alteromonas macleodii Mo169. Hydrogels with mechanical strengths (G') ranging from 0.3 kPa to 44.5 kPa were obtained as a result of the combination of different Fe3+ (0.05-9.95 g L-1) and EPS (0.3-1.7 %) concentrations. All the hydrogels had a water content above 98 %. Three different hydrogels, named HA, HB, and HC, were chosen for further characterization. With strength values (G') of 3.2, 28.9, and 44.5 kPa, respectively, these hydrogels might meet the strength requirements for several specific applications. Their mechanical resistance increased as higher Fe3+ and polymer concentrations were used in their preparation (the compressive hardness increased from 8.7 to 192.1 kPa for hydrogel HA and HC, respectively). In addition, a tighter mesh was noticed for HC, which was correlated to its lower swelling ratio value compared to HA and HB. Overall, this preliminary study highlighted the potential of these hydrogels for tissue engineering, drug delivery, or wound healing applications.

In-situ-formed immunotherapeutic and hemostatic dual drug-loaded nanohydrogel for preventing postoperative recurrence of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a prevalent malignancy characterized by an exceedingly high recurrence rate post-surgery, significantly impairing the prognosis of HCC patients. However, a standard in-care strategy for postoperative therapy is still lacking. Although encouraging results have been obtained in a newly published clinical trial for postoperative therapy by targeting the vascular endothelial growth factor (VEGF) and programmed death ligand 1 (anti-PD-L1), its efficacy remains constrained. Combining a hemostatic hydrogel with a nanoparticle-based drug delivery system presents an opportunity to optimize the antitumor effect. Herein, we developed a nanoplatform, termed HMSN@Sor/aP@Gel, comprising a hemostatic fibrin hydrogel and functionalized hollow mesoporous silica nanoparticles (HMSNs) loaded with sorafenib and anti-PD-L1 for locally administered targeted-immunotherapy to prevent the postoperative recurrence and metastasis of HCC. The antitumor mechanism is grounded in dual inhibition of Ras/Raf/MEK/ERK (MAPK) and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) pathways, synergistically complemented by PD-L1 blockade. HMSN@Sor/aP@Gel facilitates dendritic cell maturation, enhances cytotoxic T-lymphocyte infiltration, promotes the polarization of tumor-associated macrophages to M1 phenotype, induces tumor immunogenic cell death, reverses immunosuppression, and establishes immune memory to counter postoperative recurrence. Animal studies corroborate that HMSN@Sor/aP@Gel-mediated targeted immunotherapy significantly impedes primary and metastatic tumor growth and establishes immune memory to prevent recurrence post-surgery. This investigation presents a promising strategy for postoperative therapy with considerable potential for clinical translation.

Nanocomposite hydrogel microneedles: a theranostic toolbox for personalized medicine

Due to the severity and high prevalence of cancer, as well as its complex pathological condition, new strategies for cancer treatment and diagnostics are required. As such, it is important to design a toolbox that integrates multiple functions on a single smart platform. Theranostic hydrogels offer an innovative and personalized method to tackle cancer while also considering patient comfort, thereby facilitating future implementation and translation to the clinic. In terms of theranostic systems used in cancer therapy, nanoparticles are widely used as diagnostic and therapeutic tools. Nanoparticles can achieve systemic circulation, evade host defenses, and deliver drugs and signaling agents at the targeted site, to diagnose and treat the disease at a cellular and molecular level. In this context, hydrogel microneedles have a high potential for multifunctional operation in medical devices, while avoiding the complications associated with the systemic delivery of therapeutics. Compared with oral administration and subcutaneous injection, microneedles offer advantages such as better patient compliance, faster onset of action, and improved permeability and efficacy. In addition, they comprise highly biocompatible polymers with excellent degradability and tunable properties. Nanoparticles and microneedles thus offer the possibility to expand the theranostic potential through combined synergistic use of their respective features. We review herein recent advances concerning processing methods and material requirements within the realm of hydrogel microneedles as theranostic platforms, various approaches toward cancer therapy, and the incorporation of nanoparticles for added functionality.

Adjunctive Testing Using Biospectral Emission Sequencing: Bioregulatory Intelligence Technology in Parallel With the Goals of Artificial Intelligence in Medicine

The many advancements in medical technology of the last century have continually sought to improve the sensitivity of testing and the specificity of treatment of human maladies. Conventional physical and pharmaceutical treatment is largely an imprecise process, stimulating the impetus for the advancement of machine learning-enhanced artificial intelligence (AI) medical technologies. Biospectral Emission Sequencing (BES) is a bioregulatory intelligence (BI) technology already in use as an adjunct to conventional testing. Biospectral Emission Sequencing provides a functional system of dynamic real-time adjunctive testing and treatment selection. This paper discusses the parallel technologies of present and future AI and BI technologies in medicine.

Intermolecular Electrostatic Interactions in Cytochrome c Protein Monolayer on Montmorillonite Alumosilicate Surface: A Positive Cooperative Effect

Montmorillonite (MM) crystal nanoplates acquire anticancer properties when coated with the mitochondrial protein cytochrome c (cytC) due to the cancer cells' capability to phagocytize cytC-MM colloid particles. The introduced exogenous cytC initiates apoptosis: an irreversible cascade of biochemical reactions leading to cell death. In the present research, we investigate the organization of the cytC layer on the MM surface by employing physicochemical and computer methods-microelectrophoresis, static, and electric light scattering-to study cytC adsorption on the MM surface, and protein electrostatics and docking to calculate the local electric potential and Gibbs free energy of interacting protein globules. The found protein concentration dependence of the adsorbed cytC quantity is nonlinear, manifesting a positive cooperative effect that emerges when the adsorbed cytC globules occupy more than one-third of the MM surface. Computer analysis reveals that the cooperative effect is caused by the formation of protein associates in which the cytC globules are oriented with oppositely charged surfaces. The formation of dimers and trimers is accompanied by a strong reduction in the electrostatic component of the Gibbs free energy of protein association, while the van der Waals component plays a secondary role.

Topical gel formulations as potential dermal delivery carriers for green-synthesized zinc oxide nanoparticles

This study aimed to incorporate green-synthesized zinc oxide nanoparticles (ZnO NPs), functionalized with polyethylene glycol (PEG) and linked to doxorubicin (DOX), into various topical gel formulations (hydrogel, oleogel, and bigel) to enhance their dermal delivery. The ZnO NPs were produced using the aqueous extract of the root hair of Phoenix dactylifera. The optimized green-synthesized ZnO NPs, PEGylated and conjugated to DOX, demonstrated a particle size below 100 nm, low polydispersity index, and zeta potential between - 11 and - 19 mV. The UV-Vis spectroscopy analysis confirmed characteristic absorption peaks at 351 and 545 nm for ZnO and DOX, respectively. The transmission electron microscope (TEM) images revealed well-dispersed spherical nanoparticles without aggregation. Additionally, ZnO NPs-loaded gels exhibited uniformity, cohesion, no phase separation, pseudoplastic flow, and viscoelastic properties. The in vitro release studies showed that DOX-PEG-ZnO NPs hydrogel released 99.5% of DOX after 5 h of starting the release. Moreover, the penetration of DOX-PEG-ZnO NPs through excised rat skin was visualized by TEM. In conclusion, the hydrogel formulation containing green-synthesized DOX-PEG-ZnO NPs holds great promise for dermal administration in skin cancer treatment. Furthermore, the release rate and skin penetration of DOX from gels were varied based on the type of gel matrix and corroborated with their corresponding rheological properties.

Cell membrane-coated nanoparticles for targeting carcinogenic bacteria

The etiology of cancers is multifactorial, with certain bacteria established as contributors to carcinogenesis. As the understanding of carcinogenic bacteria deepens, interest in cancer treatment through bacterial eradication is growing. Among emerging antibacterial platforms, cell membrane-coated nanoparticles (CNPs), constructed by enveloping synthetic substrates with natural cell membranes, exhibit significant promise in overcoming challenges encountered by traditional antibiotics. This article reviews recent advancements in developing CNPs for targeting carcinogenic bacteria. It first summarizes the mechanisms of carcinogenic bacteria and the status of cancer treatment through bacterial eradication. Then, it reviews engineering strategies for developing highly functional and multitasking CNPs and examines the emerging applications of CNPs in combating carcinogenic bacteria. These applications include neutralizing virulence factors to enhance bacterial eradication, exploiting bacterium-host binding for precise antibiotic delivery, and modulating antibacterial immunity to inhibit bacterial growth. Overall, this article aims to inspire technological innovations in developing CNPs for effective cancer treatment through oncogenic bacterial targeting.

Composite Microgels Loaded with Doxorubicin-Conjugated Amine-Functionalized Zinc Ferrite Nanoparticles for Stimuli-Responsive Sustained Drug Release

Purpose

The purpose of this study is to address the need for efficient drug delivery with high drug encapsulation efficiency and sustained drug release. We aim to create nanoparticle-loaded microgels for potential applications in treatment development.

Methods

We adopted the process of ionic gelation to generate microgels from sodium alginate and carboxymethyl cellulose. These microgels were loaded with doxorubicin-conjugated amine-functionalized zinc ferrite nanoparticles (AZnFe-NPs). The systems were characterized using various techniques. Toxicity was evaluated in MCF-7 cells. In vitro release studies were conducted at different pH levels at 37 oC, with the drug release kinetics being analyzed using various models.

Results

The drug encapsulation efficiency of the created carriers was as high as 70%. The nanoparticle-loaded microgels exhibited pH-responsive behavior and sustained drug release. Drug release from them was mediated via a non-Fickian type of diffusion.

Conclusion

Given their high drug encapsulation efficiency, sustained drug release and pH-responsiveness, our nanoparticle-loaded microgels show promise as smart carriers for future treatment applications. Further development and research can significantly benefit the field of drug delivery and treatment development.

Evaluation of citrus pectin extraction methods: Synergistic enhancement of pectin's antioxidant capacity and gel properties through combined use of organic acids, ultrasonication, and microwaves

The biological potency of pectin is intricately intertwined with its intricate molecular architecture. The fine structure of pectin is influenced by the extraction method, while the specific impact of these methods on the fine structure and the affected attributes thereof remains enigmatic. This study delves into the profound analysis of eight distinct extraction methods influence on the structure and biological activity of citrus peel pectin. The findings demonstrate that citric acid ultrasound-assisted microwave extraction yields pectin (PectinCA-US/MV) with higher viscosity and a dense, rigid chain. Pectin extracted with acetic acid ultrasound (PectinAA-US) and citric acid ultrasound (PectinCA-US) exhibits elevated galacturonic acid (GalA) levels and reduced D-galactose (Gal) content, enhancing antioxidant activity. Eight pectin-chitosan (CS) hydrogels, especially PectinCA-US/MV-CS, demonstrate commendable thermal stability, rheological properties, self-healing capability, and swelling behavior. This study characterizes citrus peel pectin properties from different extraction methods, laying a foundation for its application in food, pharmaceuticals, and industry.

Nanoparticles incorporated hydrogels for delivery of antimicrobial agents: developments and trends

The prevention and treatment of microbial infections is an imminent global public health concern due to the poor antimicrobial performance of the existing antimicrobial regime and rapidly emerging antibiotic resistance in pathogenic microbes. In order to overcome these problems and effectively control bacterial infections, various new treatment modalities have been identified. To attempt this, various micro- and macro-molecular antimicrobial agents that function by microbial membrane disruption have been developed with improved antimicrobial activity and lesser resistance. Antimicrobial nanoparticle-hydrogels systems comprising antimicrobial agents (antibiotics, biological extracts, and antimicrobial peptides) loaded nanoparticles or antimicrobial nanoparticles (metal or metal oxide) constitute an important class of biomaterials for the prevention and treatment of infections. Hydrogels that incorporate nanoparticles can offer an effective strategy for delivering antimicrobial agents (or nanoparticles) in a controlled, sustained, and targeted manner. In this review, we have described an overview of recent advancements in nanoparticle-hydrogel hybrid systems for antimicrobial agent delivery. Firstly, we have provided an overview of the nanoparticle hydrogel system and discussed various advantages of these systems in biomedical and pharmaceutical applications. Thereafter, different hybrid hydrogel systems encapsulating antibacterial metal/metal oxide nanoparticles, polymeric nanoparticles, antibiotics, biological extracts, and antimicrobial peptides for controlling infections have been reviewed in detail. Finally, the challenges and future prospects of nanoparticle-hydrogel systems have been discussed.

Construction of a PEGDA/chitosan hydrogel incorporating mineralized copper-doped mesoporous silica nanospheres for accelerated bone regeneration

Hydrogels, integrating diverse biocompatible materials, have emerged as promising candidates for bone repair applications. This study presents a double network hydrogel designed for bone tissue engineering, combining poly(ethylene glycol) diacrylate (PEGDA) and chitosan (CS) crosslinked through UV polymerization and ionic crosslinking. Concurrently, copper-doped mesoporous silica nanospheres (Cu-MSNs) were synthesized using a one-pot method. Cu-MSNs underwent additional modification through in-situ biomineralization, resulting in the formation of an apatite layer. Polydopamine was employed to facilitate the deposition of Calcium (Ca) and Phosphate (P) ions on the surface of Cu-MSNs (Cu-MSNs/PDA@CaP). Composite hydrogels were created by integrating varied concentrations of Cu-MSNs/PDA@CaP (25, 50, 100, 150, 200 μg/mL). Characterization unveiled distinctive interconnected porous structures within the composite hydrogel, showcasing a notable 169.6 % enhancement in compressive stress (elevating from 89.01 to 240.19 kPa) compared to pure PEGDA. In vitro biocompatibility experiments illustrated that the composite hydrogel maintained elevated cell viability (up to 106.6 %) and facilitated rapid cell proliferation over 7 days. The hydrogel demonstrated a substantial 57.58 % rise in ALP expression and a surprising 235.27 % increase in ARS staining. Moreover, it significantly enhanced the expression of crucial osteogenic genes, such as run-related transcription factors 2 (RUNX2), collagen 1a1 (Col1a1), and secreted phosphoprotein 1 (Spp1), establishing it as a promising scaffold for bone regeneration. This study shows how Cu-MSNs/PDA@CaP were successfully integrated into a double network hydrogel, resulting in a composite material with good biological responses. Due to its improved characteristics, this composite hydrogel holds the potential for advancing bone regeneration procedures.

Intratumoral Lactate Depletion Based on Injectable Nanoparticles-Hydrogel Composite System Synergizes with Immunotherapy against Postablative Hepatocellular Carcinoma Recurrence

Thermal ablation is a crucial therapeutic modality for hepatocellular carcinoma (HCC), but its efficacy is often hindered by the high recurrence rate attributed to insufficient ablation. Furthermore, the residual tumors following insufficient ablation exhibit a more pronounced immunosuppressive state, which accelerates the disease progression and leads to immune checkpoint blockade (ICB) resistance. Herein, evidence is presented that heightened intratumoral lactate accumulation, stemming from the augmented glycolytic activity of postablative residual HCC cells, may serve as a crucial driving force in exacerbating the immunosuppressive state of the tumor microenvironment (TME). To address this, an injectable nanoparticles-hydrogel composite system (LOX-MnO2 @Gel) is designed that gradually releases lactate oxidase (LOX)-loaded hollow mesoporous MnO2 nanoparticles at the tumor site to continuously deplete intratumoral lactate via a cascade catalytic reaction. Using subcutaneous and orthotopic HCC tumor-bearing mouse models, it is confirmed that LOX-MnO2 @Gel-mediated local lactate depletion can transform the immunosuppressive postablative TME into an immunocompetent one and synergizes with ICB therapy to significantly inhibit residual HCC growth and lung metastasis, thereby prolonging the survival of mice postablation. The work proposes an appealing strategy for synergistically combining antitumor metabolic therapy with immunotherapy to combat postablative HCC recurrence.

Highly oriented hydrogels for tissue regeneration: design strategies, cellular mechanisms, and biomedical applications

Many human tissues exhibit a highly oriented architecture that confers them with distinct mechanical properties, enabling adaptation to diverse and challenging environments. Hydrogels, with their water-rich "soft and wet" structure, have emerged as promising biomimetic materials in tissue engineering for repairing and replacing damaged tissues and organs. Highly oriented hydrogels can especially emulate the structural orientation found in human tissue, exhibiting unique physiological functions and properties absent in traditional homogeneous isotropic hydrogels. The design and preparation of highly oriented hydrogels involve strategies like including hydrogels with highly oriented nanofillers, polymer-chain networks, void channels, and microfabricated structures. Understanding the specific mechanism of action of how these highly oriented hydrogels affect cell behavior and their biological applications for repairing highly oriented tissues such as the cornea, skin, skeletal muscle, tendon, ligament, cartilage, bone, blood vessels, heart, etc., requires further exploration and generalization. Therefore, this review aims to fill that gap by focusing on the design strategy of highly oriented hydrogels and their application in the field of tissue engineering. Furthermore, we provide a detailed discussion on the application of highly oriented hydrogels in various tissues and organs and the mechanisms through which highly oriented structures influence cell behavior.

Chenodeoxycholic Acid-Loaded Nanoparticles Are Sufficient to Decrease Adipocyte Size by Inducing Mitochondrial Function

Excess fat accumulation is not only associated with metabolic diseases but also negatively impacts physical appearance and emotional well-being. Bile acid, the body's natural emulsifier, is one of the few FDA-approved noninvasive therapeutic options for double chin (submental fat) reduction. Synthetic sodium deoxycholic acid (NaDCA) causes adipose cell lysis; however, its side effects include inflammation, bruising, and necrosis. Therefore, we investigated if an endogenous bile acid, chenodeoxycholic acid (CDCA), a well-known signaling molecule, can be beneficial without many of the untoward effects. We first generated CDCA-loaded nanoparticles to achieve sustained and localized delivery. Then, we injected them into the subcutaneous fat depot and monitored adipocyte size and mitochondrial function. Unlike NaDCA, CDCA did not cause cytolysis. Instead, we demonstrate that a single injection of CDCA-loaded nanoparticles into the subcutaneous fat reduced the adipocyte size by promoting fat burning and mitochondrial respiration, highlighting their potential for submental fat reduction.

Augmented physical, mechanical, and cellular responsiveness of gelatin-aldehyde modified xanthan hydrogel through incorporation of silicon nanoparticles for bone tissue engineering

Bioactive scaffolds fabricated from a combination of organic and inorganic biomaterials are a promising approach for addressing defects in bone tissue engineering. In the present study, a self-crosslinked nanocomposite hydrogel, composed of gelatin/aldehyde-modified xanthan (Gel-AXG) is successfully developed by varying concentrations of porous silicon nanoparticles (PSiNPs). The effect of PSiNPs incorporation on physical, mechanical, and biological performance of the nanocomposite hydrogel is evaluated. Morphological analysis reveals formation of highly porous 3D microstructures with interconnected pores in all nanocomposite hydrogels. Increased content of PSiNPs results in a lower swelling ratio, reduced porosity and pore size, which in turn impeded media penetration and slowed down the degradation process. In addition, remarkable enhancements in dynamic mechanical properties are observed in Gel-AXG-8%Si (compressive strength: 0.6223 MPa at 90 % strain and compressive modulus: 0.054 MPa), along with improved biomineralization ability via hydroxyapatite formation after immersion in simulated body fluid (SBF). This optimized nanocomposite hydrogel provides a sustained release of Si ions at safe dose levels. Furthermore, in-vitro cytocompatibility studies using MG-63 cells exhibited remarkable performance in terms of cell attachment, proliferation, and ALP activity for Gel-AXG-8%Si. These findings suggest that the prepared nanocomposite hydrogel holds promising potential as a scaffold for bone tissue engineering.

Harnessing the power of biological macromolecules in hydrogels for controlled drug release in the central nervous system: A review

Hydrogels have immense potential in revolutionizing central nervous system (CNS) drug delivery, improving outcomes for neurological disorders. They serve as promising tools for controlled drug delivery to the CNS. Available hydrogel types include natural macromolecules (e.g., chitosan, hyaluronic acid, alginate), as well as hybrid hydrogels combining natural and synthetic polymers. Each type offers distinct advantages in terms of biocompatibility, mechanical properties, and drug release kinetics. Design and engineering considerations encompass hydrogel composition, crosslinking density, porosity, and strategies for targeted drug delivery. The review emphasizes factors affecting drug release profiles, such as hydrogel properties and formulation parameters. CNS drug delivery applications of hydrogels span a wide range of therapeutics, including small molecules, proteins and peptides, and nucleic acids. However, challenges like limited biodegradability, clearance, and effective CNS delivery persist. Incorporating 3D bioprinting technology with hydrogel-based CNS drug delivery holds the promise of highly personalized and precisely controlled therapeutic interventions for neurological disorders. The review explores emerging technologies like 3D bioprinting and nanotechnology as opportunities for enhanced precision and effectiveness in hydrogel-based CNS drug delivery. Continued research, collaboration, and technological advancements are vital for translating hydrogel-based therapies into clinical practice, benefiting patients with CNS disorders. This comprehensive review article delves into hydrogels for CNS drug delivery, addressing their types, design principles, applications, challenges, and opportunities for clinical translation.

Activating the delivery of a model drug to lipid membrane by encapsulation of cyclodextrin: Combined experimental and molecular docking studies

Drug delivery science is always an important topic as it studies the delivery of therapeutic payloads to the desired target cells without affecting the healthy tissues/cells, thus minimizing drug-induced toxicity. Aiming towards the targeted drug delivery, the present project deals with the delivery of a polarity-sensitive solvatochromic model drug, namely, salt of 8-anilinonaphthalene-1-sulphonic acid (ANSA) to the model bio-membrane (which mimic several aspects of the real cell membrane), more precisely at the lipid-water interface of L-α-Dipalmitoylphosphatidylcholine (DPPC) phospholipid. The drug delivery process has been activated through the binding of dye with cyclodextrin, acting as a drug transporter. Detailed steady-state and time-resolved spectroscopic studies including molecular docking analysis imply the targeted drug delivery of dye, ANSA, towards the lipid-water interface region of lipid bilayers through encapsulation within the cyclodextrin void. Stronger binding interaction of the dye with the lipid bilayers relative to β-cyclodextrin (β-CD) is the foremost reason for the targeted delivery. The present biophysical interaction studies of drug-lipid interaction, thus, may provide a cordial approach for drug formulation and drug delivery.

Force-Triggered Self-Destructive Hydrogels

Self-destructive polymers (SDPs) are defined as a class of smart polymers that autonomously degrade upon experiencing an external trigger, such as a chemical cue or optical excitation. Because SDPs release the materials trapped inside the network upon degradation, they have potential applications in drug delivery and analytical sensing. However, no known SDPs that respond to external mechanical forces have been reported, as it is fundamentally challenging to create mechano-sensitivity in general and especially so for force levels below those required for classical force-induced bond scission. To address this challenge, the development of force-triggered SDPs composed of DNA crosslinked hydrogels doped with nucleases is described here. Externally applied piconewton forces selectively expose enzymatic cleavage sites within the DNA crosslinks, resulting in rapid polymer self-degradation. The synthesis and the chemical and mechanical characterization of DNA crosslinked hydrogels, as well as the kinetics of force-triggered hydrolysis, are described. As a proof-of-concept, force-triggered and time-dependent rheological changes in the polymer as well as encapsulated nanoparticle release are demonstrated. Finally, that the kinetics of self-destruction are shown to be tuned as a function of nuclease concentration, incubation time, and thermodynamic stability of DNA crosslinkers.

Directing cellular responses in a nanocomposite 3D matrix for tissue regeneration with nanoparticle-mediated drug delivery

Hydrogels play an important role in tissue engineering due to their native extracellular matrix-like characteristics, but they are insufficient in providing the necessary stimuli to support tissue formation. Efforts to integrate bioactive cues directly into hydrogels are hindered by incompatibility with hydrophobic drugs, issues of burst/uncontrolled release, and rapid degradation of the bioactive molecules. Skeletal muscle tissue repair requires internal stimuli and communication between cells for regeneration, and nanocomposite systems offer to improve the therapeutic effects in tissue regeneration. Here, the versatility of mesoporous silica nanoparticles (MSN) was leveraged to formulate a nanoparticle-hydrogel composite and to combine the benefits of controlled delivery of bioactive cues and cellular support. The tunable surface characteristics of MSNs were exploited to optimize homogeneity and intracellular drug delivery in a 3D matrix. Nanocomposite hydrogels formulated with acetylated or succinylated MSNs achieved high homogeneity in 3D distribution, with succinylated MSNs being rapidly internalized and acetylated MSNs exhibiting slower cellular uptake. MSN-hydrogel nanocomposites simultaneously allowed efficient local intracellular delivery of a hydrophobic model drug. To further study the efficiency of directing cell response, a Notch signaling inhibitor (DAPT) was incorporated into succinylated MSNs and incorporated into the hydrogel. MSN-hydrogel nanocomposites effectively downregulated the Notch signaling target genes, and accelerated and maintained the expression of myogenic markers. The current findings demonstrate a proof-of-concept in effective surface engineering strategies for MSN-based nanocomposites, suited for hydrophobic drug delivery in tissue regeneration with guided cues.

Drug Delivery of Gelatin Nanoparticles as a Biodegradable Polymer for the Treatment of Infectious Diseases: Perspectives and Challenges

In recent years, there has been a growing interest in the use of gelatin nanoparticles (GNPs) for the treatment of infectious diseases. The inherent properties of these nanoparticles make them attractive options for drug delivery. Their biocompatibility ensures that they can interact with biological systems without causing adverse reactions, while their biodegradability ensures that they can break down harmlessly in the body once their function is performed. Furthermore, their capacity for controlled drug release ensures that therapeutic agents can be delivered over a sustained period, thereby enhancing treatment efficacy. This review examines the current landscape of GNP-based drug delivery, with a specific focus on its potential applications and challenges in the context of infectious diseases. Key challenges include controlling drug release rates, ensuring nanoparticle stability under physiological conditions, scaling up production while maintaining quality, mitigating potential immunogenic reactions, optimizing drug loading efficiency, and tracking the biodistribution and clearance of GNPs in the body. Despite these hurdles, GNPs hold promising potential in the realm of infectious disease treatment. Ongoing research and innovation are essential to overcome these obstacles and completely harness the potential of GNPs in clinical applications.

Nanoengineered injectable hydrogels derived from layered double hydroxides and alginate for sustained release of protein therapeutics in tissue engineering applications

Chronic Kidney Disease (CKD) which involves gradual loss of kidney function is characterized by low levels of a glycoprotein called Erythropoietin (EPO) that leads to red blood cell  deficiency and anemia. Recombinant human EPO (rhEPO) injections that are administered intravenously or subcutaneously is the current gold standard for treating CKD. The rhEPO injections have very short half-lives and thus demands frequent administration with a risk of high endogenous EPO levels leading to severe side effects that could prove fatal. To this effect, this work provides a novel approach of using lamellar inorganic solids with a brucite-like structure for controlling the release of protein therapeutics such as rhEPO in injectable hydrogels. The nanoengineered injectable system was formulated by incorporating two-dimensional layered double hydroxide (LDH) clay materials with a high surface area into alginate hydrogels for sustained delivery. The inclusion of LDH in the hydrogel network not only improved the mechanical properties of the hydrogels (5-30 times that of alginate hydrogel) but also exhibited a high binding affinity to proteins without altering their bioactivity and conformation. Furthermore, the nanoengineered injectable hydrogels (INHs) demonstrated quick gelation, injectability, and excellent adhesion properties on human skin. The in vitro release test of EPO from conventional alginate hydrogels (Alg-Gel) showed 86% EPO release within 108 h while INHs showed greater control over the initial burst and released only 24% of EPO in the same incubation time. INH-based ink was successfully used for 3D printing, resulting in scaffolds with good shape fidelity and stability in cell culture media. Controlled release of EPO from INHs facilitated superior angiogenic potential in ovo (chick chorioallantoic membrane) compared to Alg-Gel. When subcutaneously implanted in albino mice, the INHs formed a stable gel in vivo without inducing any adverse effects. The results suggest that the proposed INHs in this study can be utilized as a minimally invasive injectable platform or as 3D printed patches for the delivery of protein therapeutics to facilitate tissue regeneration.

Hydrogel drug delivery systems for minimally invasive local immunotherapy of cancer

Although systemic immunotherapy has achieved durable responses and improved survival for certain patients and cancer types, low response rates and immune system-related systemic toxicities limit its overall impact. Intratumoral (intralesional) delivery of immunotherapy is a promising technique to combat mechanisms of tumor immune suppression within the tumor microenvironment and reduce systemic drug exposure and associated side effects. However, intratumoral injections are prone to variable tumor drug distribution and leakage into surrounding tissues, which can compromise efficacy and contribute to toxicity. Controlled release drug delivery systems such as in situ-forming hydrogels are promising vehicles for addressing these challenges by providing improved spatio-temporal control of locally administered immunotherapies with the goal of promoting systemic tumor-specific immune responses and abscopal effects. In this review we will discuss concepts, applications, and challenges in local delivery of immunotherapy using controlled release drug delivery systems with a focus on intratumorally injected hydrogel-based drug carriers.

Development of a novel NiCu nanoparticle-loaded polysaccharide-based hydrogel for 3D printing of customizable dressings with promising cytotoxicity against melanoma cells

Polysaccharide hydrogels and metal alloy nanoparticles have already found use in a range of biomedical applications. Nickel-copper nanoparticles (NiCu NPs) are particularly promising due to their tunable properties, such as ferromagnetism, biocompatibility, and antimicrobial activity. At the same time, polysaccharide hydrogels made of polymer mixtures such as alginate and methylcellulose with incorporated metal alloy nanoparticles are reported in the scientific literature. In view of this, in this work, NiCu NPs are combined with polysaccharide hydrogels and 3D printed to construct geometrically customizable dressings with tailorable properties for melanoma treatment. This novel combination exploits the intrinsic magnetic properties of NiCu NPs and the same time builds on their less known properties to improve the mechanic stability of 3D printed materials, both contributing to a previously not reported application as potent cytotoxic dressing against melanoma cells. The dressings were evaluated in terms of their physico-chemical characteristics, and their potential application, namely melanoma cell cytotoxicity. While all dressings exhibited similar degradation profiles regardless of composition, the addition of NiCu NPs had an effect on the hydrophilicity, swelling rates, and topographical properties of the dressings. Compression results showed that the presence of NPs increased the stiffness of the dressings, while the ultimate tensile strength was highest at 0.31 MPa for the dressings with 0.5 wt% NPs. We show that although the base formulation of the dressings is biocompatible with skin-derived cells, dressings loaded with NPs exhibit promising antimelanoma activity. Extracts obtained from dressings containing 0.5 wt% NPs reduced melanoma cell viability to 61% ± 11% and 40% ± 2% after 24 h and 72 h of soaking, respectively. Furthermore, extracts of dressings with 1 wt% NPs reduced melanoma cell viability to less than 15% within the first 24 h. By adjusting the NP content, the mechanical properties, surface roughness, and wettability can be tuned so that the dressings can be functionally customized. In addition, by using 3D printing as a fabrication process, the shape and composition of the dressings can be tailored to the patient's needs. The dressings also remained intact after soaking in simulated physiological solution for 14 days, indicating their suitability for long-term topical application.

Gel/hydrogel-based in situ biomaterial platforms for cancer postoperative treatment and recovery

Tumor surgical resection is the major strategy for cancer treatment. Meanwhile, perioperative treatment especially the postoperative adjuvant anticancer strategies play essential roles in satisfying therapeutic results and rapid recovery. Postoperative tumor recurrence, metastasis, bleeding, inter-tissue adhesion, infection, and delayed wound healing are vital risks that could lead to poor prognosis or even treatment failure. Therefore, methods targeting these postoperative complications are in desperate need. In situ biomaterial-based drug delivery platforms are promising candidates for postoperative treatment and recovery, resulting from their excellent properties including good biocompatibility, adaptive shape, limited systemic effect, designable function, and easy drug loading. In this review, we focus on introducing the gel/hydrogel-based in situ biomaterial platforms involving their properties, advantages, and synthesis procedures. Based on the loaded contents in the gel/hydrogel such as anticancer drugs, immunologic agents, cell components, and multifunctional nanoparticles, we further discuss the applications of the in situ platforms for postoperative tumor recurrence and metastasis inhibition. Finally, other functions aiming at fast postoperative recovery were introduced, including hemostasis, antibacterial infection, adhesion prevention, tissue repair, and wound healing. In conclusion, gel/hydrogel is a developing and promising platform for postoperative treatment, exhibiting gratifying therapeutic effects and inconspicuous toxicity to normal tissues, which deserves further research and exploration.

Thermo-Responsive Hydrogels Encapsulating Targeted Core-Shell Nanoparticles as Injectable Drug Delivery Systems

As therapeutic agents that allow for minimally invasive administration, injectable biomaterials stand out as effective tools with tunable properties. Furthermore, hydrogels with responsive features present potential platforms for delivering therapeutics to desired sites in the body. Herein, temperature-responsive hydrogel scaffolds with embedded targeted nanoparticles were utilized to achieve controlled drug delivery via local drug administration. Poly(N-isopropylacrylamide) (pNIPAM) hydrogels, prepared with an ethylene-glycol-based cross-linker, demonstrated thermo-sensitive gelation ability upon injection into environments at body temperature. This hydrogel network was engineered to provide a slow and controlled drug release profile by being incorporated with curcumin-loaded nanoparticles bearing high encapsulation efficiency. A core (alginate)-shell (chitosan) nanoparticle design was preferred to ensure the stability of the drug molecules encapsulated in the core and to provide slower drug release. Nanoparticle-embedded hydrogels were shown to release curcumin at least four times slower compared to the free nanoparticle itself and to possess high water uptake capacity and more mechanically stable viscoelastic behavior. Moreover, this therapy has the potential to specifically address tumor tissues over-expressing folate receptors like ovaries, as the nanoparticles target the receptors by folic acid conjugation to the periphery. Together with its temperature-driven injectability, it can be concluded that this hydrogel scaffold with drug-loaded and embedded folate-targeting nanoparticles would provide effective therapy for tumor tissues accessible via minimally invasive routes and be beneficial for post-operative drug administration after tumor resection.

Immune homeostasis modulation by hydrogel-guided delivery systems: a tool for accelerated bone regeneration

Immune homeostasis is delicately mediated by the dynamic balance between effector immune cells and regulatory immune cells. Local deviations from immune homeostasis in the microenvironment of bone fractures, caused by an increased ratio of effector to regulatory cues, can lead to excessive inflammatory conditions and hinder bone regeneration. Therefore, achieving effective and localized immunomodulation of bone fractures is crucial for successful bone regeneration. Recent research has focused on developing localized and specific immunomodulatory strategies using local hydrogel-based delivery systems. In this review, we aim to emphasize the significant role of immune homeostasis in bone regeneration, explore local hydrogel-based delivery systems, discuss emerging trends in immunomodulation for enhancing bone regeneration, and address the limitations of current delivery strategies along with the challenges of clinical translation.

Chitosan-Based Hydrogels for Infected Wound Treatment

Wound infections slow down the healing process and lead to complications such as septicemia, osteomyelitis, and even death. Although traditional methods relying on antibiotics are effective in controlling infection, they have led to the emergence of antibiotic-resistant bacteria. Hydrogels with antimicrobial function become a viable option for reducing bacterial colonization and infection while also accelerating healing processes. Chitosan is extensively developed as antibacterial wound dressings due to its unique biochemical properties and inherent antibacterial activity. In this review, the recent research progress of chitosan-based hydrogels for infected wound treatment, including the fabrication methods, antibacterial mechanisms, antibacterial performance, wound healing efficacy, etc., is summarized. A concise assessment of current limitations and future trends is presented.

Targeted micro-heterogeneity in bioinks allows for 3D printing of complex constructs with improved resolution and cell viability

Three-dimensional bioprinting is an evolving versatile technique for biomedical applications. Ideal bioinks have complex micro-environment that mimic human tissue, allow for good printing quality and provide high cell viability after printing. Here we present two strategies for enhancing gelatin-based bioinks heterogeneity on a 1-100µm length scale resulting in superior printing quality and high cell viability. A thorough spatial and micro-mechanical characterization of swollen hydrogel heterogeneity was done using multiple particle tracking microrheology. When poly(vinyl alcohol) is added to homogeneous gelatin gels, viscous inclusions are formed due to micro-phase separation. This phenomenon leads to pronounced slip and superior printing quality of complex 3D constructs as well as high human hepatocellular carcinoma (HepG2) and normal human dermal fibroblast (NHDF) cell viability due to reduced shear damage during extrusion. Similar printability and cell viability results are obtained with gelatin/nanoclay composites. The formation of polymer/nanoclay clusters reduces the critical stress of gel fracture, which facilitates extrusion, thus enhancing printing quality and cell viability. Targeted introduction of micro-heterogeneities in bioinks through micro-phase separation is an effective technique for high resolution 3D printing of complex constructs with high cell viability. The size of the heterogeneities, however, has to be substantially smaller than the desired feature size in order to achieve good printing quality.

Free-flowing, self-crosslinking, carboxymethyl starch and carboxymethyl cellulose microgels, as smart hydrogel dressings for wound repair

Hydrogels are widely recognized and favoured as moist wound dressings due to their beneficial properties. However, their limited capacity to absorb fluids restricts their use in highly exuding wounds. Microgels are small sized hydrogels that have recently gained considerable attention in drug delivery applications due to their superior swelling behaviour and ease of application. In this study, we introduce dehydrated microgel particles (μGeld) that rapidly swell and interconnect, forming an integrated hydrogel when exposed to fluid. These free-flowing microgel particles, derived from the interaction of carboxymethylated forms of starch and cellulose, have been designed to significantly absorb fluid and release silver nanoparticles in order to effectively control infection. Studies using simulated wound models validated the microgels ability to efficiently regulate the wound exudate and create a moist environment. While the biocompatibility and hemocompatibility studies confirmed the safety of the μGel particles, its haemostatic property was established using relevant models. Furthermore, the promising results from a full-thickness wounds in rats have highlighted the enhanced healing potential of the microgel particles. These findings suggest that the dehydrated microgels can evolve as a new class of smart wound dressings.

Mussel-inspired self-healing hydrogel form pectin and cellulose for hemostasis and diabetic wound repairing

Diabetic wound is considered as a kind of chronic wound prone to infection and difficult to repair due to high glucose level in the blood of patients. In this research, a biodegradable self-healing hydrogel with mussel inspired bioadhesion and anti-oxidation properties is fabricated based on Schiff-base cross-linking. The hydrogel was designed from dopamine coupled pectin hydrazide (Pec-DH) and oxidized carboxymethyl cellulose (DCMC) for mEGF loading as a diabetic wound repair dressing. The Pectin and CMC as natural feedstock endowed the hydrogel with biodegradability to avoid possible side effects, while the coupled catechol structure could enhance the tissue adhesion of the hydrogel for hemostasis. The results showed the Pec-DH/DCMC hydrogel formed fast and can cover irregular wounds with good sealing effect. The catechol structure also improved the reactive oxygen species (ROS) scavenging ability of the hydrogel, which can eliminate the negative effect of ROS during wound healing. The in vivo diabetic wound healing experiment revealed the hydrogel as mEGF loading vehicle greatly enhanced the diabetic wound repairing rate in mice model. As a result, the Pec-DH/DCMC hydrogel could show advantages as EGF carrier in wound healing applications.

Immunostimulatory DNA Hydrogel Enhances Protective Efficacy of Nanotoxoids against Bacterial Infection

While vaccines have been highly successful in protecting against various infections, there are still many high-priority pathogens for which there are no clinically approved formulations. To overcome this challenge, researchers have explored the use of nanoparticulate strategies for more effective antigen delivery to the immune system. Along these lines, nanotoxoids are a promising biomimetic platform that leverages cell membrane coating technology to safely deliver otherwise toxic bacterial antigens in their native form for antivirulence vaccination. Here, in order to further boost their immunogenicity, nanotoxoids formulated against staphylococcal α-hemolysin are embedded into a DNA-based hydrogel with immunostimulatory CpG motifs. The resulting nanoparticle-hydrogel composite is injectable and improves the in vivo delivery of vaccine antigens while simultaneously stimulating nearby immune cells. This leads to elevated antibody production and stronger antigen-specific cellular immune responses. In murine models of pneumonia and skin infection caused by methicillin-resistant Staphylococcus aureus, mice vaccinated with the hybrid vaccine formulation are well-protected. This work highlights the benefits of combining nanoparticulate antigen delivery systems with immunostimulatory hydrogels into a single platform, and the approach can be readily generalized to a wide range of infectious diseases.