Progress of gelatin-based microspheres (GMSs) as delivery vehicles of drug and cell

Advances in drug-loaded microspheres for targeted, controlled, and sustained drug delivery: Potential, applications, and future directions

Drug-loaded microspheres are an innovative technology in drug delivery systems (DDS), addressing many limitations of conventional methods. Their ability to enable controlled release, precise targeting, and broad drug compatibility makes them a versatile platform with significant potential in modern medicine. This review explores the unique properties of microspheres, including their biocompatibility, biodegradability, and customizable architecture, positioning them as promising candidates for therapeutic use in cancer, diabetes, and rheumatoid arthritis. These characteristics enhance drug stability and bioavailability while reducing systemic side effects, improving patient outcomes. The key findings discussed in this review highlight critical factors influencing microsphere performance, including material selection, particle size, surface modification, and multi-drug loading strategies. Particularly, the integration of nanoscale materials and the combination of microsphere technology with gene therapy and immunotherapy have shown great potential to improve treatment precision and efficacy. However, challenges such as large-scale production, reproducibility, and optimization of drug release profiles remain significant hurdles. Large-scale manufacturing of microspheres with consistent size, efficient drug loading, and predictable release patterns is technically complex, and optimizing release, especially for drugs with narrow therapeutic windows, requires a deeper understanding of the interactions between drugs and polymers. Future advances in microsphere technology are expected to leverage innovations in nanotechnology, gene therapy, and immunotherapy. These advancements may enable more efficient and personalized treatments for diseases that were previously difficult to treat. The findings presented in this review emphasize the transformative potential of microspheres in revolutionizing drug delivery, offering safer, more effective, and patient-specific therapies.

Construction of a methacrylated gelatine composite hydrogel based on tachyplesin II and its application in the repair of infected wounds

Tachyplesin II (TP) is a β-folded peptide isolated from horseshoe crabs. TP, with two disulfide bonds, effectively inhibits gram-negative and gram-positive bacteria, fungi and viruses. In this study, the antibacterial and antioxidant properties of synthetic TP were examined. Specifically, TP was incorporated into cross-linked methacrylated gelatine (GelMA) to construct a GelMA-TP hydrogel, which promoted infected wound healing. TP formed intermolecular hydrogen bonds with the GelMA network, endowing the GelMA-TP hydrogel with good antibacterial activity, stable rheological properties, high swelling capacity, self-healing behaviour, and good biocompatibility. We found that the anti-inflammatory and antioxidant activities of the GelMA-TP hydrogel significantly enhanced collagen production, thus accelerating healing in a rat-infected wound model. Overall, the GelMA-TP hydrogel demonstrates significant potential to stimulate the healing of infected wounds by reducing healing time and improving tissue repair outcomes. These findings highlight its translational promise as a clinically effective material for managing complex wounds, particularly in scenarios where conventional therapies are limited by persistent infections or excessive inflammation.

Esterase-responsive kartogenin composite hydrogel microspheres boost nucleus pulposus regeneration in intervertebral disc degeneration

Cell transplantation for nucleus pulposus (NP) regeneration represents a promising strategy for intervertebral disc degeneration (IVDD). Nonetheless, the hostile microenvironment within the degenerated intervertebral discs, characterized by redox imbalance and elevated mechanical pressure, poses risks of low cell survival and inadequate cell colonization for efficient NP regeneration. To address these challenges, we developed a biomimetic, esterase-responsive composite hydrogel microsphere (GHKM) for cell delivery, consisting of gelatin methacrylate (GelMA) mixed with HAMA-KGN, a conjugate of hyaluronic acid methacrylate (HAMA) and the small heterocyclic molecule kartogenin (KGN) via ester bonds. GHKM mimic the NP extracellular matrix (ECM), providing essential adhesion and mechanical support for cell proliferation, while facilitating cellular adaptation to the adverse microenvironment through the esterase-responsive release of KGN. Furthermore, GHKM exhibit favorable biocompatibility and promote or protect ECM synthesis by nucleus pulposus cells (NPCs) under both normal and inflammatory conditions. Transcriptomic sequencing analysis indicates a correlation between enhanced ECM synthesis and enrichment of antioxidant-related pathways. Subsequent cellular biological studies reveal that GHKM can also reduce reactive oxygen species production within the inflammatory milieu. The underlying mechanism of its protective effect on matrix metabolism may involve the activation of nuclear factor erythroid 2-related factor 2 (NRF2) and the upregulation of downstream antioxidant enzymes. In vivo implantation of NPCs-laden GHKM into rat tail nuclectomy models for 4 and 8 weeks preserved disc height, structure, and biological function, with histological analysis confirming NP regeneration. These findings present GHKM as a promising, synergistic transplantation strategy for NP regeneration in IVDD. STATEMENT OF SIGNIFICANCE: This study introduces an esterase-responsive gelatin methacrylate/hyaluronic acid methacrylate-kartogenin composite hydrogel microsphere (GHKM) system, aimed at mimicing the extracellular matrix (ECM) of the nucleus pulposus (NP) to address the pressing challenge of intervertebral disc degeneration (IVDD). These microspheres offer an innovative solution for cell transplantation therapy by simultaneously addressing two critical barriers: the harsh microenvironment of the degenerated disc and the need for sustained therapeutic effects. GHKM provide mechanical support, enhance cell survival, and adapt dynamically to adverse conditions through esterase-responsive release of kartogenin (KGN), a multifunctional molecule with chondrogenic, anti-inflammatory, and antioxidative properties. This study will not only interest researchers focused on regenerative medicine and biomaterials but also inspire new directions for tackling complex degenerative diseases.

Biodegradable Double-Layer Hydrogels with Sequential Drug Release for Multi-Phase Collaborative Regulation in Scar-Free Wound Healing

Scarring is a prevalent and often undesirable outcome of the wound healing process, impacting millions worldwide. The complex and dynamic nature of wound healing, including hemostasis, inflammation, proliferation, and remodeling, necessitates precise, making it hard for stage-specific interventions to prevent pathological scarring. This study introduces a double-layer hydrogel system designed for sequential drug release, aligning with the stage-specific need for wound healing. The lower layer, containing curcumin-loaded chitosan nanoparticles, shows early anti-inflammatory and antioxidant effects, while the upper layer, with pirfenidone-encapsulated gelatin microspheres, presents late-stage anti-fibrotic activity. The hydrogel's unique design, with varying degradation rates and mechanical properties in each layer, facilitates cascade drug release in synchrony with wound healing stages. Rapid release of curcumin from the lower layer promotes proliferation by mitigating inflammation and oxidative stress, while the sustained release of pirfenidone from the upper layer inhibits excessive fibrillation during late proliferation and remodeling. In a rat model of full-thickness skin defect, treatment with a double-layer hydrogel drug delivery system accelerated the wound closure, improved scar quality, and promoted the formation of hair follicles. Therefore, this innovative approach lays a promising foundation for future clinical applications in anti-scar therapies, offering a significant advancement in wound care and regenerative medicine.

Drug delivery for platinum therapeutics

Cancer remains a severe threat to human health. Platinum drugs, such as cisplatin (CDDP), oxaliplatin, and carboplatin, are extensively utilized for treating various cancers and have become the primary drugs in first-line treatments for numerous solid tumors due to their effective anticancer properties. However, their side effects, including drug resistance, nephrotoxicity and ototoxicity, limit the clinical application. Therefore, there is an urgent need to develop targeted delivery and controlled release systems for platinum drugs to address the disadvantages, enhancing tumor accumulation and improving therapeutic effects. In this review, we first review the progress of platinum drugs, their anticancer mechanism, clinical applications and limitations. Then, we comprehensively summarize the platinum-based delivery using drug carriers and responsive strategies. We especially highlight the platinum-delivery formulations in ongoing clinical trials. Finally, we provide perspectives for this field. The review could provide an increasingly in-depth understanding of platinum therapeutics and motivate increasing delivery tactics to overcome the limitations of platinum application.

A novel method for encapsulating nutritional supplements within edible films

Many nutritional supplements are hydrophobic solids or oils that are extremely difficult to administer in tablet form. These supplements are often consumed as large soft gels that may represent a choking hazard. In addition, many nutritional supplements produce an aversive taste or tactile response when consumed orally. Because of these limitations, improved delivery methods for administering nutritional supplements to the oral cavity represent an important goal. In this study, vitamin E acetate is exploited as a model nutritional supplement for developing an improved oral delivery method by encapsulating this vitamin within rapidly dissolving edible films. Vitamin E acetate was solidified by mixing this oil with a long-chain fatty alcohol. The resulting wax was then pulverized and added to an aqueous polymer solution that included melted gelatin. The mixture was then sonicated to form a stable emulsion that was dried to a thin, flexible film. Vitamin E acetate was successfully encapsulated within films at amounts that approximated the minimum daily requirement for this supplement. Minimal loss of this vitamin occurred when the emulsion was dried to a film. Average film thickness was 150 µm, and the encapsulated vitamin E was not degraded. Film formulations that included the excipients sucralose and peppermint oil produced taste intensity ratings in the moderate range, and displayed favorable hedonic responses. In summary, rapidly dissolving edible films have been developed that greatly increase the load capacity of a hydrophobic oral supplement. These edible films represent a promising approach for delivering hydrophobic oils or solids to the oral cavity at bioavailable amounts.

Microalgae-based biodegradable embolic agent for the treatment of hepatocellular carcinoma through transarterial embolization

Transarterial chemoembolization (TACE) serves as a locoregional therapy for hepatocellular carcinoma (HCC) patients. Nevertheless, the rapid dissociation of conventional TACE (cTACE) preparations, attributed to the instability of the emulsion, often leads to inadequate concentrations of chemotherapeutic agents within the tumor site. Consequently, there exists a pressing demand for an embolic agent that possesses facile injectability and the capacity to provide continuous delivery of chemotherapy drugs. Herein, we leveraged the inherent drug-loading capabilities and distinctive structural attributes of Spirulina platensis (SP) to formulate a novel microalgae embolic agent, doxorubicin loaded-Spirulina platensis (DOX-SP). The DOX-SP formulation exhibited a notable capacity for drug loading and demonstrated the ability to sustain drug release in response to acidic tumor microenvironments (TME). The spiral structure and micron-scale size of SP contributed to effective vascular embolization and continuous localized release of DOX. Furthermore, the biodegradability of SP as a natural biomaterial ensured good biosafety, with its degradation products potentially enhancing the pH of TME. In a rat model of in-situ hepatocellular carcinoma, DOX-SP effectively suppressed tumor growth and significantly reduced tumor size following intra-arterial injection, while exhibiting minimal adverse effects. Taken together, the high drug loading capacity, effective vascular embolization, pH sensitivity, TME pH modulation, and biodegradability of DOX-SP made it a promising embolic agent for hepatocellular carcinoma treatment.

Nanomedicine Approaches for Intervertebral Disc Regeneration: From Bench to Bedside

Intervertebral disc degeneration (IDD) is a leading cause of low back pain (LBP) and neurological dysfunction, contributing significantly to disability-adjusted life years globally. The progression of IDD is driven by excessive oxidative stress, inflammation, apoptosis, and fibrosis, which disrupt the balance between anabolic and catabolic processes, leading to extracellular matrix (ECM) degradation and IDD. Current treatment options, such as conservative therapy and surgical intervention, are limited in halting the disease progression and often exacerbate degeneration in adjacent discs. This review highlights the challenges in treating IDD, particularly due to the limited drug delivery efficiency to the intervertebral disc (IVD). It explores the potential of nanobiomedicine and various nanomaterial-based delivery systems, including nanoparticles, microspheres, gene-nanocomplexes, fullerene, exosomes, and nanomaterial-composite hydrogels. These advanced delivery systems can enhance targeted drug delivery, improve local drug concentration, and sustain drug retention within the IVD, offering promising therapeutic strategies to address IDD. The review also examines the therapeutic effects of these nanomaterials on IDD, focusing on their impact on metabolism, inflammation, apoptosis, fibrosis, and stem cell migration and differentiation, aiming to provide innovative strategies for intervertebral disc regeneration.

Drug Repurposing and Nanotechnology for Topical Skin Cancer Treatment: Redirecting toward Targeted and Synergistic Antitumor Effects

Skin cancer represents a major health concern due to its rising incidence and limited treatment options. Current treatments (surgery, chemotherapy, radiotherapy, immunotherapy, and targeted therapy) often entail high costs, patient inconvenience, significant adverse effects, and limited therapeutic efficacy. The search for novel treatment options is also marked by the high capital investment and extensive development involved in the drug discovery process. In response to these challenges, repurposing existing drugs for topical application and optimizing their delivery through nanotechnology could be the answer. This innovative strategy aims to combine the advantages of the known pharmacological background of commonly used drugs to expedite therapeutic development, with nanosystem-based formulations, which among other advantages allow for improved skin permeation and retention and overall higher therapeutic efficacy and safety. The present review provides a critical analysis of repurposed drugs such as doxycycline, itraconazole, niclosamide, simvastatin, leflunomide, metformin, and celecoxib, formulated into different nanosystems, namely, nanoemulsions and nanoemulgels, nanodispersions, solid lipid nanoparticles, nanostructured lipid carriers, polymeric nanoparticles, hybrid lipid-polymer nanoparticles, hybrid electrospun nanofibrous scaffolds, liposomes and liposomal gels, ethosomes and ethosomal gels, and aspasomes, for improved outcomes in the battle against skin cancer. Enhanced antitumor effects on melanoma and nonmelanoma research models are highlighted, with some nanoparticles even showing intrinsic anticancer properties, leading to synergistic effects. The explored research findings highly evidence the potential of these approaches to complement the currently available therapeutic strategies in the hope that these treatments might one day reach the pharmaceutical market.

Catechol-rich gelatin microspheres as restorative medical implants intended for inhibiting seroma formation and promoting wound healing

Seroma formation and poor wound healing are common complications of many surgeries that create anatomical dead space (i.e., mastectomy), often causing tissue infection and even necrosis. Although negative pressure drainage and tissue adhesives are investigated to alleviate fluid accumulation post-surgery, however, their therapeutic efficacy remains unsatisfactory in most cases. Herein, the catechol-rich chemically crosslinked gelatin microspheres (ca-CGMSs) have been developed as biodegradable reconstructive implants for preventing seroma formation and concurrently promoting subcutaneous wound healing. Compared with the most representative hydrogel adhesive, i.e. commercial porcine fibrin sealant (PFS), the loosely packed ca-CGMSs with diameters range from 50 to 350 μm, provide numerous cell-adhesive interfaces and interconnected macro-pores for enhanced cell adhesion, proliferation and migration. Subcutaneous embedding trials show the in situ swelling aggregation and wet tissue adhesion of ca-CGMSs as well as their capacity in recruiting autologous cells in rat mastectomy models. The trials in rabbit mastectomy models demonstrate that, compared with PFS gluing, the implanted dried ca-CGMSs not only significantly inhibit seroma formation, but also achieve enhanced wound healing by inducing the formation of vascularized neo-tissue. The ca-CGMSs show a great potential to be the next-generation of restorative materials for both preventing seroma formation and healing subcutaneous wounds.

Synergy of engineered gelatin methacrylate-based porous microspheres and multicellular assembly to promote osteogenesis and angiogenesis in bone tissue reconstruction

One of the key challenges in bone defects treatment is providing adequate and stable blood supply during new tissue regeneration. Mesenchymal stem cells (MSCs) and endothelial cells (ECs) have great potential to promote osteogenesis and angiogenesis during bone defect repair through paracrine effects, but their therapeutic efficacy depends on effective cellular assembly and delivery. In this work, we developed various microspheres with different pore sizes for multi-cellular delivery to enhance the angiogenic and osteogenic capability via combining microfluidic and gradient freeze-drying techniques. The particle and pore size of fabricated porous gelatin methacrylate (GelMA)-based hydrogel microspheres (PGMS) could be controllable through adjusting the freezing time of hydrogel microspheres, the range of particles and pores size are 150-250 μm and 10-100 μm with different freezing time from 0 min to 30 min. The optimized particle size (200.8 ± 14.2 μm) and pore size (11.2 ± 1.9 μm) were explored to promote cell assemble, adhesion, growth, and proliferation in the PGMS. Furthermore, the co-assembly and delivery of bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) on the PGMS was achieved and an optimal cellular ratio of BMSCs to HUVECs (20:2) was established for co-culturing of them to achieve optimal paracrine effects, further promoting osteogenic differentiation and angiogenesis. Finally, results from both in vitro and in vivo experiments showed that the developed PGMS with co-assembly of BMSCs to HUVECs contributed to accelerate bone regeneration and vascularization process daringly, exhibited great potential in vascularized bone tissue reconstruction.

Design and preparation of hydrogel microspheres for spinal cord injury repair

A severe disorder known as spinal cord damage causes both motor and sensory impairment in the limbs, significantly reducing the patients' quality of life. After a spinal cord injury, functional recovery and therapy have emerged as critical concerns. Hydrogel microspheres have garnered a lot of interest lately because of their enormous promise in the field of spinal cord injury rehabilitation. The material classification of hydrogel microspheres (natural and synthetic macromolecule polymers) and their synthesis methods are examined in this work. This work also covers the introduction of several kinds of hydrogel microspheres and their use as carriers in the realm of treating spinal cord injuries. Lastly, the study reviews the future prospects for hydrogel microspheres and highlights their limitations and problems. This paper can offer feasible ideas for researchers to advance the application of hydrogel microspheres in the field of spinal cord injury.

Effect of Sinapine on Microstructure and Anti-Digestion Properties of Dual-Protein-Based Hydrogels

Sinapine is a natural polyphenol from the cruciferous plant family that has anti-aging effects but is low in bioavailability. To improve the bioavailability and therapeutic effect of sinapine, sinapine-crosslinked dual-protein-based hydrogels were prepared using soy protein isolate as a cross-linking agent. The preparation conditions were optimized by single-factor experiments, and the optimal ratios were obtained as follows: the concentration of sinapine was 300 μg/mL; the water-oil ratio was 1:3. The encapsulation rate was greater than 95%, and the drug loading capacity was 3.5 mg/g. In vitro, digestion experiments showed that the dual-protein-based hydrogels as a drug carrier stabilized the release of sinapine and improved the bioavailability of sinapine by 19.3%. The IC50 of DPPH antioxidants was 25 μg/mL as determined by in vitro digestion, and the antioxidant capacity of ABTS was about 20% higher than that of glutaraldehyde control. This is due to the addition of sinapine to enhance the antioxidant properties of the system. It can be seen that the developed hydrogels have potential applications in related fields, such as food nutrition fortification and drug delivery.

Tailoring silk fibroin fibrous architecture by a high-yield electrospinning method for fast wound healing possibilities

In this study, a novel array electrospinning collector was devised to generate two distinct regenerated silk fibroin (SF) fibrous membranes: ordered and disordered. Leveraging electrostatic forces during the electrospinning process allowed precise control over the orientation of SF fiber, resulting in the creation of membranes comprising both aligned and randomly arranged fiber layers. This innovative approach resulted in the development of large-area membranes featuring exceptional stability due to their alternating patterned structure, achievable through expansion using the collector, and improving the aligned fiber membrane mechanical properties. The study delved into exploring the potential of these membranes in augmenting wound healing efficiency. Conducting in vitro toxicity assays with adipose tissue-derived mesenchymal stem cells (AD-MSCs) and normal human dermal fibroblasts (NHDFs) confirmed the biocompatibility of the SF membranes. We use dual perspectives on exploring the effects of different conditioned mediums produced by cells and structural cues of materials on NHDFs migration. The nanofibers providing the microenvironment can directly guide NHDFs migration and also affect the AD-MSCs and NHDFs paracrine effects, which can improve the chemotaxis of NHDFs migration. The ordered membrane, in particular, exhibited pronounced effectiveness in guiding directional cell migration. This research underscores the revelation that customizable microenvironments facilitated by SF membranes optimize the paracrine products of mesenchymal stem cells and offer valuable physical cues, presenting novel prospects for enhancing wound healing efficiency.

Mechanical Properties, Drug Release, Biocompatibility, and Antibacterial Activities of Modified Emulsified Gelatin Microsphere Loaded with Gentamicin Composite Calcium Phosphate Bone Cement In Vitro

Bone defects are commonly addressed with bone graft substitutes; however, surgical procedures, particularly for open and complex fractures, may pose a risk of infection. As such, a course of antibiotics combined with a drug carrier is often administered to mitigate potential exacerbations. This study involved the preparation and modification of emulsified (Em) crosslinking-gelatin (gel) microspheres (m-Em) to reduce their toxicity. The antibiotic gentamicin was impregnated into gel microspheres (m-EmG), which were incorporated into calcium phosphate bone cement (CPC). The study investigated the effects of m-EmG@CPC on antibacterial activity, mechanical properties, biocompatibility, and proliferation and mineralization of mouse progenitor osteoblasts (D1 cells). The average size of the gel microspheres ranged from 22.5 to 16.1 μm, with no significant difference between the groups (p > 0.05). Most of the oil content within the microspheres was transferred through modification, resulting in reduced cytotoxicity. Furthermore, antibiotic-impregnated m-EmG did not compromise the intrinsic properties of the microspheres and exhibited remarkably antibacterial effects. After combining with CPC (m-EmG@CPC), the microspheres did not significantly hinder the CPC reaction and produced the main product, hydroxyapatite (HA). However, the compressive strength of the largest microsphere content of 0.5 wt.% m-EmG in CPC decreased significantly from 59.8 MPa of CPC alone to 38.7 MPa of 0.5m-EmG@CPC (p < 0.05). The 0.5m-EmG@CPC composite was effective against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in drug release and antibacterial tests. Compared with m-EmG alone, the 0.5m-EmG@CPC composite showed no toxicity to mouse fibroblast cells (L929). Additionally, the proliferation and mineralization of mouse osteoblastic osteoprogenitor cells (D1 cells) did not have a negative impact on the 0.5m-EmG@CPC composite over time in culture compared with CPC alone. Results suggest that the newly developed antibacterial 0.5m-EmG@CPC composite bone cement did not negatively affect the performance of osteoprogenitor cells and could be a new option for bone graft replacement in surgeries.

Fabrication of polymeric microspheres for biomedical applications

Polymeric microspheres (PMs) have attracted great attention in the field of biomedicine in the last several decades due to their small particle size, special functionalities shown on the surface and high surface-to-volume ratio. However, how to fabricate PMs which can meet the clinical needs and transform laboratory achievements to industrial scale-up still remains a challenge. Therefore, advanced fabrication technologies are pursued. In this review, we summarize the technologies used to fabricate PMs, including emulsion-based methods, microfluidics, spray drying, coacervation, supercritical fluid and superhydrophobic surface-mediated method and their advantages and disadvantages. We also review the different structures, properties and functions of the PMs and their applications in the fields of drug delivery, cell encapsulation and expansion, scaffolds in tissue engineering, transcatheter arterial embolization and artificial cells. Moreover, we discuss existing challenges and future perspectives for advancing fabrication technologies and biomedical applications of PMs.

Effect of Microsphere Concentration on Catechin Release from Microneedle Arrays

In this work, microspheres were developed by cross-linking glutaraldehyde in an aqueous gelatin solution with a surfactant and solvent. A poly(vinyl alcohol) (PVA) solution was produced and combined with catechin-loaded microspheres. Different microsphere concentrations (0%, 5%, 10%, and 15%) were applied to the PVA microneedles. The moisture content, particle size, swelling, and drug release percentage of microneedles were studied using various microsphere concentrations. Fourier transform infrared and scanning electron microscopy (SEM) investigations validated the structure of gelatin microspheres as well as their decoration in microneedles. The SEM scans revealed that spherical microspheres with a wrinkled and folded morphology were created, with no physical holes visible on the surface. The gelatin microspheres generated had a mean particle size of 20-30 μm. Ex vivo release analysis indicated that microneedles containing 10% microspheres released the most catechin, with 42.9% at 12 h and 84.4% at 24 h.

Hierarchical Composite Scaffold with Deferoxamine Delivery System to Promote Bone Regeneration via Optimizing Angiogenesis

A bone defect refers to the loss of bone tissue caused by trauma or lesion. Bone defects result in high morbidity and deformity rates worldwide. Autologous bone grafting has been widely applied in clinics as the gold standard of treatment; however, it has limitations. Hence, bone tissue engineering has been proposed and developed as a novel therapeutic strategy for treating bone defects. Rapid and effective vascularization is essential for bone regeneration. In this study, a hierarchical composite scaffold with deferoxamine (DFO) delivery system, DFO@GMs-pDA/PCL-HNTs (DGPN), is developed, focusing on vascularized bone regeneration. The hierarchical structure of DGPN imitates the microstructure of natural bone and interacts with the local extracellular matrix, facilitating cell adhesion and proliferation. The addition of 1 wt% of halloysite nanotubes (HNTs) improves the material properties. Hydrophilic and functional groups conferred by polydopamine (pDA) modifications strengthen the scaffold bioactivity. Gelatin microspheres (GMs) protect the pharmacological activity of DFO, achieving local application and sustained release for 7 days. DFO effectively promotes angiogenesis by activating the signaling pathway of hypoxia inducible factor-1 α. In addition, DFO synergizes with HNTs to promote osteogenic differentiation and matrix mineralization. These results indicate that DGPN promotes bone regeneration and accelerates cranial defect healing.

Microfluidic printed 3D bioactive scaffolds for postoperative treatment of gastric cancer

Tumor recurrence and tissue regeneration are two major challenges in the postoperative treatment of cancer. Current research hotspots are focusing on developing novel scaffold materials that can simultaneously suppress tumor recurrence and promote tissue repair. Here, we propose a microfluidic 3D-printed methacrylate fish gelatin (F-GelMA@BBR) scaffold loaded with berberine (BBR) for the postoperative treatment of gastric cancer. The F-GelMA@BBR scaffold displayed a significant killing effect on gastric cancer MKN-45 cells in vitro and demonstrated excellent anti-recurrence efficiency in gastric cancer postoperative models. In vitro experiments have shown that F-GelMA@BBR exhibits significant cytotoxicity on gastric cancer cells while maintaining the cell viability of normal cells. The results of in vivo experiments show that F-GelMA@BBR can significantly suppress the tumor volume to 49.7 % of the control group. In addition, the scaffold has an ordered porous structure and good biocompatibility, which could support the attachment and proliferation of normal cells to promote tissue repair at the tumor resection site. These features indicated that such scaffold material is a promising candidate for postoperative tumor treatment in the practical application.

Nanoclay-Modified Hyaluronic Acid Microspheres for Bone Induction by Sustained rhBMP-2 Delivery

Microspheres (MSs) are ideal candidates as biological scaffolds loading with growth factors or cells for bone tissue engineering to repair irregular alveolar bone defects by minimally invasive injection. However, the high initial burst release of growth factor and low cell attachment limit the application of microspheres. The modification of microspheres often needs expensive experiments facility or complex chemical reactions, which is difficult to achieve and may bring other problems. In this study, a sol-grade nanoclay, laponite XLS is used to modify the surface of MSs to enhance its affinity to either positively or negatively charged proteins and cells without changing the interior structure of the MSs. Recombinant human bone morphogenetic protein-2 (rhBMP-2) is used as a representation of growth factor to check the osteoinduction ability of laponite XLS-modified MSs. By modification, the protein sustained release, cell loading, and osteoinduction ability of MSs are improved. Modified by 1% laponite XLS, the MSs can not only promote osteogenic differentiation of MC3T3-E1 cells by themselves, but also enhance the effect of the rhBMP-2 below the effective dose. Collectively, the study provides an easy and viable method to modify the biological behavior of microspheres for bone tissue regeneration.

Preparation and application of hemostatic microspheres containing biological macromolecules and others

Bleeding from uncontrollable wounds can be fatal, and the body's clotting mechanisms are unable to control bleeding in a timely and effective manner in emergencies such as battlefields and traffic accidents. For irregular and inaccessible wounds, hemostatic materials are needed to intervene to stop bleeding. Hemostatic microspheres are promising for hemostasis, as their unique structural features can promote coagulation. There is a wide choice of materials for the preparation of microspheres, and the modification of natural macromolecular materials such as chitosan to enhance the hemostatic properties and make up for the deficiencies of synthetic macromolecular materials makes the hemostatic microspheres multifunctional and expands the application fields of hemostatic microspheres. Here, we focus on the hemostatic mechanism of different materials and the preparation methods of microspheres, and introduce the modification methods, related properties and applications (in cancer therapy) for the structural characteristics of hemostatic microspheres. Finally, we discuss the future trends of hemostatic microspheres and research opportunities for developing the next generation of hemostatic microsphere materials.

Advanced Drug Carriers: A Review of Selected Protein, Polysaccharide, and Lipid Drug Delivery Platforms

Studies on bionanocomposite drug carriers are a key area in the field of active substance delivery, introducing innovative approaches to improve drug therapy. Such drug carriers play a crucial role in enhancing the bioavailability of active substances, affecting therapy efficiency and precision. The targeted delivery of drugs to the targeted sites of action and minimization of toxicity to the body is becoming possible through the use of these advanced carriers. Recent research has focused on bionanocomposite structures based on biopolymers, including lipids, polysaccharides, and proteins. This review paper is focused on the description of lipid-containing nanocomposite carriers (including liposomes, lipid emulsions, lipid nanoparticles, solid lipid nanoparticles, and nanostructured lipid carriers), polysaccharide-containing nanocomposite carriers (including alginate and cellulose), and protein-containing nanocomposite carriers (e.g., gelatin and albumin). It was demonstrated in many investigations that such carriers show the ability to load therapeutic substances efficiently and precisely control drug release. They also demonstrated desirable biocompatibility, which is a promising sign for their potential application in drug therapy. The development of bionanocomposite drug carriers indicates a novel approach to improving drug delivery processes, which has the potential to contribute to significant advances in the field of pharmacology, improving therapeutic efficacy while minimizing side effects.

Gelatin microsphere-alginate hydrogel combined system for sustained and gastric targeted delivery of 5-fluorouracil

In the current study, novel gelatin microspheres/methacrylated alginate hydrogel combined system (5-FU-GELms/Alg-MA) was developed for gastric targeted delivery of 5-fluorouracil as an anticancer agent. While water-in-oil emulsification method was used for the production of 5-FU-GELms, Alg-MA was synthesized through methacrylation reaction occurred by epoxide ring-opening mechanism. Then, 5-FU-GELms/Alg-MA hydrogel system was fabricated by the encapsulation of 5-FU-GELms into Alg-MA hydrogel network via UV-crosslinking. To evaluate applicability of fabricated 5-FU-GELms/Alg-MA as gastric targeted drug delivery vehicle, both swelling and in vitro drug release experiments were carried out at pH 1.2 medium resembling gastric fluid. Compared to drug release directly from 5-FU-GELms, 5-FU-GELms/Alg-MA hydrogel system showed more controlled and sustained drug release profile with lower amount of cumulative release starting from early stages, since hydrogel matrix created a barrier to the diffusion of 5-FU included in microspheres. Drug release kinetic results obtained by applying various kinetic models to release data showed that the mechanism of 5-FU release from 5-FU-GELms/Alg-MA hydrogel system is controlled by Fickian diffusion. All results revealed that 5-FU-GELms/Alg-MA hydrogel integrated system could be potentially utilized as gastric targeted drug carrier to enhance therapeutic efficacy and reduce systemic side effects in gastric cancer treatments for future studies.

Curcumin-encapsulated fish gelatin-based microparticles from microfluidic electrospray for postoperative gastric cancer treatment

Gastric cancer is the fifth most frequently diagnosed malignant neoplasm and the third leading cause of cancer-related mortality. Nevertheless, the therapeutic efficacy of conventional surgical and chemotherapeutic interventions in clinical practice is often unsatisfactory. Curcumin (Cur) has shown promise as a therapeutic agent in prior studies. However, its progress in this context has been impeded by challenges including low solubility, instability in aqueous environments, and rapid metabolism. In this study, we develop methacrylate fish gelatin (FGMA) hydrogel microparticles (FGMPs@Cur) encapsulating Cur via microfluidic electrospray technology for postoperative comprehensive treatment of gastric cancer. Comprehensive characterizations and analyses were conducted to assess the cytotoxicity against gastric cancer cells and potential tissue reparative effects of FGMPs@Cur. In vitro experiments revealed that FGMPs@Cur exhibited a remarkable cytotoxic effect on nearly 80 % of gastric cancer cells while maintaining at least 95 % viability of normal cells in cell compatibility tests. In vivo results demonstrated that FGMPs@Cur significantly reduced tumor volume to 47 % of the control group, and notable tissue regeneration was observed at the surgical site. These properties indicated that such a hydrogel microparticle system is a promising candidate for postoperative gastric cancer treatment in practical application.

Hydrogel Microparticles for Bone Regeneration

Hydrogel microparticles (HMPs) stand out as promising entities in the realm of bone tissue regeneration, primarily due to their versatile capabilities in delivering cells and bioactive molecules/drugs. Their significance is underscored by distinct attributes such as injectability, biodegradability, high porosity, and mechanical tunability. These characteristics play a pivotal role in fostering vasculature formation, facilitating mineral deposition, and contributing to the overall regeneration of bone tissue. Fabricated through diverse techniques (batch emulsion, microfluidics, lithography, and electrohydrodynamic spraying), HMPs exhibit multifunctionality, serving as vehicles for drug and cell delivery, providing structural scaffolding, and functioning as bioinks for advanced 3D-printing applications. Distinguishing themselves from other scaffolds like bulk hydrogels, cryogels, foams, meshes, and fibers, HMPs provide a higher surface-area-to-volume ratio, promoting improved interactions with the surrounding tissues and facilitating the efficient delivery of cells and bioactive molecules. Notably, their minimally invasive injectability and modular properties, offering various designs and configurations, contribute to their attractiveness for biomedical applications. This comprehensive review aims to delve into the progressive advancements in HMPs, specifically for bone regeneration. The exploration encompasses synthesis and functionalization techniques, providing an understanding of their diverse applications, as documented in the existing literature. The overarching goal is to shed light on the advantages and potential of HMPs within the field of engineering bone tissue.

Chitosan-Reinforced Gelatin Microspheres-Modified Glass Ionomer Cement (GIC): A Novel Bone Alloplast Graft Material Synthesis and an In Vivo Analysis

Aim and objective The study aimed to assess and evaluate the efficacy of glass ionomer modified with chitosan-reinforced gelatin microspheres on bone formation. Materials and methods  The study involved three groups: Group I comprised plain glass ionomer cement; Group II comprised glass ionomer cement/gelatin (70:30 wt%); in Group III, glass ionomer cement/gelatin/chitosan (70:30%) scaffold were made into discs; the gelatin microspheres were synthesized by oil emulsion method. The synthesized scaffold was subjected to the following in vitro testing, Instron Universal Testing Machine (UTM), U3000, (Instron Corporation, Norwood, Massachusetts, United States) to assess compressive strength, scanning electron microscope (SEM) examination, and biocompatibility testing using hemocompatibility assay. The material was then tested in vivo; male Wistar albino rats, a total of nine animals, were utilized for this purpose. Three animals were used in each group; a femoral defect model was the model of choice for the experiment and the animals were observed for a period of four weeks, following which the animals were sacrificed and sent for histopathological analysis. Results The compression testing was carried out using UTM; test group I was 33 MPa, test group II was 2.3 MPa, and test group III was 25.75 MPa. SEM (JSM-IT800 Schottky Field Emission NANO SEM (JEOL, Tokyo, Japan)) analysis was done to observe the porosity of the fabricated scaffold with the average measurement of 0.12 ± 0.2 μm in test group II and 0.29 ± 0.4 μm in test group III. Hemocompatibility reports noted 0.4-0.8% lysis for the synthesized scaffolds. Histopathology staining of the femur defects showed that group III favoured bone formation. One-way analysis of variance (ANOVA) and post hoc Bonferroni test was done on the data. The optical density values of the alizarin red stained slide showed statistical significance for group III. Conclusion In conclusion, the synthesized scaffolds are biocompatible, distribution of porosity and pore characteristics in the glass ionomer cement/gelatin/chitosan group is better than that of the glass ionomer cement/gelatin group. The glass ionomer cement/gelatin/chitosan group had better compressive strength and induced more bone formation compared to the other test group and the control. Thus, the novel glass ionomer modified with chitosan-reinforced gelatin microspheres has optimal properties to be used as a bone graft material.

Progress in microsphere-based scaffolds in bone/cartilage tissue engineering

Bone/cartilage repair and regeneration have been popular and difficult issues in medical research. Tissue engineering is rapidly evolving to provide new solutions to this problem, and the key point is to design the appropriate scaffold biomaterial. In recent years, microsphere-based scaffolds have been considered suitable scaffold materials for bone/cartilage injury repair because microporous structures can form more internal space for better cell proliferation and other cellular activities, and these composite scaffolds can provide physical/chemical signals for neotissue formation with higher efficiency. This paper reviews the research progress of microsphere-based scaffolds in bone/chondral tissue engineering, briefly introduces types of microspheres made from polymer, inorganic and composite materials, discusses the preparation methods of microspheres and the exploration of suitable microsphere pore size in bone and cartilage tissue engineering, and finally details the application of microsphere-based scaffolds in biomimetic scaffolds, cell proliferation and drug delivery systems.

Fucoidan-functionalized gelatin methacryloyl microspheres ameliorate intervertebral disc degeneration by restoring redox and matrix homeostasis of nucleus pulposus

Loss of extracellular matrix (ECM) and dehydration of the nucleus pulposus (NP) are major pathological characteristics of intervertebral disc degeneration (IVDD), the leading cause of low back pain. Excessive reactive oxygen species (ROS) induced by proinflammatory cytokines substantially contribute to IVDD pathogenesis. This study aimed to examine the potential of fucoidan in protecting the matrix metabolism of NP cells and its therapeutic efficacy in the prevention of IVDD. In an inflammatory environment induced by interleukin (IL)-1β, fucoidan treatments demonstrated a dose-dependent enhancement of ECM production in NP cells, while concurrently reducing the expression of matrix degradation enzymes. The protective effect of fucoidan was mediated through the activation of nuclear factor erythroid 2-related factor 2 (NRF2) and subsequent induction of antioxidant enzymes, whereas silencing Nrf2 abrogated the protection of fucoidan on NP cells against IL-1β-induced oxidative stress. Moreover, a novel fucoidan-functionalized gelatin methacryloyl microsphere (Fu@GelMA-MS) was synthesized. The in vivo application of Fu@GelMA-MS via in situ injection in a rat caudal IVD model effectively conserved the ECM components and maintained the hydration of the NP tissue, thereby preventing IVDD caused by puncture. Collectively, fucoidan-functionalized hydrogel microspheres represent a promising strategy for the regeneration of NP and the treatment of IVDD.

A controllable gelatin-based microcarriers fabrication system for the whole procedures of MSCs amplification and tissue engineering

Biopolymer microbeads present substantial benefits for cell expansion, tissue engineering, and drug release applications. However, a fabrication system capable of producing homogeneous microspheres with high precision and controllability for cell proliferation, passaging, harvesting and downstream application is limited. Therefore, we developed a co-flow microfluidics-based system for the generation of uniform and size-controllable gelatin-based microcarriers (GMs) for mesenchymal stromal cells (MSCs) expansion and tissue engineering. Our evaluation of GMs revealed superior homogeneity and efficiency of cellular attachment, expansion and harvest, and MSCs expanded on GMs exhibited high viability while retaining differentiation multipotency. Optimization of passaging and harvesting protocols was achieved through the addition of blank GMs and treatment with collagenase, respectively. Furthermore, we demonstrated that MSC-loaded GMs were printable and could serve as building blocks for tissue regeneration scaffolds. These results suggested that our platform held promise for the fabrication of uniform GMs with downstream application of MSC culture, expansion and tissue engineering.

Injectable rBMSCs-laden hydrogel microspheres loaded with naringin for osteomyelitis treatment

Osteomyelitis, caused by purulent bacteria invading bone tissue, often occurs in long bones and seriously affects the physical and mental health and working ability of patients; it can even endanger life. However, due to bone cavity structure, osteomyelitis tends to occur inside the bone and thus lacks an effective treatment; anti-inflammatory treatment and repair of bone defects are necessary. Here, we developed injectable hydrogel microspheres loaded with naringin and bone marrow mesenchymal stem cells, which have anti-inflammatory and osteogenic properties. These homogeneous microspheres, ranging from 200 to 1000μm, can be rapidly fabricated using an electro-assisted bio-fabrication method. Interestingly, it was found that microspheres with relatively small diameters (200μm) were more conducive to the initial cell attachment, growth, spread, and later osteogenic differentiation. The developed microspheres can effectively treat tibial osteomyelitis in rats within six weeks, proving their prospects for clinical application.

Plasma Modification Techniques for Natural Polymer-Based Drug Delivery Systems

Natural polymers have attracted significant attention in drug delivery applications due to their biocompatibility, biodegradability, and versatility. However, their surface properties often limit their use as drug delivery vehicles, as they may exhibit poor wettability, weak adhesion, and inadequate drug loading and release. Plasma treatment is a promising surface modification technique that can overcome these limitations by introducing various functional groups onto the natural polymer surface, thus enhancing its physicochemical and biological properties. This review provides a critical overview of recent advances in the plasma modification of natural polymer-based drug delivery systems, with a focus on controllable plasma treatment techniques. The review covers the fundamental principles of plasma generation, process control, and characterization of plasma-treated natural polymer surfaces. It discusses the various applications of plasma-modified natural polymer-based drug delivery systems, including improved biocompatibility, controlled drug release, and targeted drug delivery. The challenges and emerging trends in the field of plasma modification of natural polymer-based drug delivery systems are also highlighted. The review concludes with a discussion of the potential of controllable plasma treatment as a versatile and effective tool for the surface functionalization of natural polymer-based drug delivery systems.

Bone marrow mesenchymal stem cells response on collagen/hyaluronan/chondroitin scaffold enriched with gentamicin -loaded gelatin microparticles for skin tissue engineering

The repair and functional reconstruction of large skin defects caused by burn remains an intractable clinical problem. Collagen type I (ColI) was extracted from carp scales and confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis ultraviolet adsorption spectra and automatic amino acid analyzer. Then the scaffolds containing the purified ColI, hyaluronic acid (HA) and chondroitin sulfate (CS) were constructed and examined. The results showed that the scaffold (ColI:CS:HA=9:1:1) had larger pore diameter, porosity, water absorption, degradation rate and tensile strength. gentamycin sulphate (GS) - gelatin microspheres (GMSs) were prepared by emulsion cross-linking method. The drug release study of the ColI-CS-HA-GS/GMSs scaffold with antibacterial property showed a prolonged, continuous, and sustained release of GS. The bone marrow mesenchymal stem cells (BMSCs) were extracted from rat and inoculated into the ColI-HA-CS-GS/GMSs scaffold. The results performed that the scaffold could accelerate proliferation of the BMSCs and wound healing.

In Vitro Characterizations of Post-Crosslinked Gelatin-Based Microspheres Modified by Phosphatidylcholine or Diammonium Phosphate as Antibiotic Delivery Vehicles

Hydrogel-based microspheres prepared by emulsification have been widely used as drug carriers, but biocompatibility remains a challenging issue. In this study, gelatin was used as the water phase, paraffin oil was used as the oil phase, and Span 80 was used as the surfactant. Microspheres were prepared using a water-in-oil (W/O) emulsification. Diammonium phosphate (DAP) or phosphatidylcholine (PC) were further used to improve the biocompatibility of post-crosslinked gelatin microspheres. The biocompatibility of DAP-modified microspheres (0.5-10 wt.%) was better than that of PC (5 wt.%). The microspheres soaked in phosphate-buffered saline (PBS) lasted up to 26 days before fully degrading. Based on microscopic observation, the microspheres were all spherical and hollow inside. The particle size distribution ranged from 19 μm to 22 μm in diameter. The drug release analysis showed that the antibiotic gentamicin loaded on the microspheres was released in a large amount within 2 h of soaking in PBS. It was stabilized until the amount of microspheres integrated was significantly reduced after soaking for 16 days and then released again to form a two-stage drug release curve. In vitro experiments showed that DAP-modified microspheres at concentrations less than 5 wt.% had no cytotoxicity. Antibiotic-impregnated and DAP-modified microspheres had good antibacterial effects against Staphylococcus aureus and Escherichia coli, but these drug-impregnated groups hinder the biocompatibility of hydrogel microspheres. The developed drug carrier can be combined with other biomaterial matrices to form a composite for delivering drugs directly to the affected area in the future to achieve local therapeutic effects and improve the bioavailability of drugs.

The Role of Microsphere Structures in Bottom-Up Bone Tissue Engineering

Bone defects have caused immense healthcare concerns and economic burdens throughout the world. Traditional autologous allogeneic bone grafts have many drawbacks, so the emergence of bone tissue engineering brings new hope. Bone tissue engineering is an interdisciplinary biomedical engineering method that involves scaffold materials, seed cells, and "growth factors". However, the traditional construction approach is not flexible and is unable to adapt to the specific shape of the defect, causing the cells inside the bone to be unable to receive adequate nourishment. Therefore, a simple but effective solution using the "bottom-up" method is proposed. Microspheres are structures with diameters ranging from 1 to 1000 µm that can be used as supports for cell growth, either in the form of a scaffold or in the form of a drug delivery system. Herein, we address a variety of strategies for the production of microspheres, the classification of raw materials, and drug loading, as well as analyze new strategies for the use of microspheres in bone tissue engineering. We also consider new perspectives and possible directions for future development.

Gelatin Microspheres Loaded with Wharton's Jelly Mesenchymal Stem Cells Promote Acute Full-Thickness Skin Wound Healing and Regeneration in Mice

Objective: At present, there is an urgent need to develop a novel and practical therapeutic approach to accelerate the healing of acute wounds. Mesenchymal stem cell (MSC)-based therapy is emerging as a promising therapeutic approach for acute skin wounds. However, there are still challenges in clinical application of this strategy, such as low survivability, low retention time, and less engraftment in skin wounds. Approach: Wharton's jelly mesenchymal stem cells (WJMSCs) were seeded into three-dimensional (3D) gelatin microspheres (GMs) to identify the biocompatibility of GMs. WJMSCs were embedded in GMs and then encapsulated with Pluronic F-127 (PF-127) and sodium ascorbyl phosphate (SAP) combination to transplant onto acute full-thickness skin wound in mice. Histology, immunohistochemistry, and immunofluorescence assay were used to investigate the skin wound healing, dermis regeneration, collagen deposition, cell proliferation, and neovascularization. Results: Three-dimensional GM had strong biocompatibility, compared with two-dimensional adherent culturing, GM loading increased the cell viability and proliferation ability of WJMSCs. WJMSCs+GM+PF-127+SAP transplantation increased skin wound healing rate, dermis regeneration, and type III collagen deposition through improving macrophage polarization, cell proliferation, neovascularization, cell retention, and engraftment at skin wound site. Innovation: The effective 3D encapsulation technology for WJMSCs solved the main problems of cell activity and residence time during MSC transplantation. WJMSCs+GM+PF-127+SAP transplantation will be a new and effective MSC biomaterials-based therapeutic strategy for acute skin traumatic wounds. Conclusion: WJMSCs+GM+PF-127+SAP transplantation facilitated acute full-thickness skin wound healing and regeneration and might be a new and effective therapy for acute skin traumatic wounds.

Injectable temperature-sensitive hydrogel system incorporating deferoxamine-loaded microspheres promotes H-type blood vessel-related bone repair of a critical size femoral defect

Insufficient vascularization is a major challenge in the repair of critical-sized bone defects. Deferoxamine (DFO) has been reported to play a potential role in promoting the formation of H-type blood vessels, a specialized vascular subtype with coupled angiogenesis and osteogenesis. However, whether DFO promotes the expression of H-type vessels in critical femoral defects with complete periosteal damage remains unknown. Moreover, stable drug loading systems need to be designed owing to the short half-life and high-dose toxic effects of DFO. In this study, we developed an injectable DFO-gelatin microspheres (GMs) hydrogel complex as a stable drug loading system for the treatment of critical femoral defects in rats. Our results showed that sustained release of DFO in critical femoral defects stimulated the generation of functional H-type vessels. The DFO-GMs hydrogel complex effectively promoted proliferation, formation, and migration of human umbilical vein endothelial cells in vitro. In vivo, the application of the DFO-GMs hydrogel complex expanded the distribution range and prolonged the expression time of H-type vessels in the defect area and was positively correlated with the number of osterix+ cells and new bone tissue. Topical application of the HIF-1α inhibitor PX-478 partially blocked the stimulation of H-type vessels by DFO, whereas the osteogenic potential of the latter was also weakened. Our results extended the local application of DFO and provided a theoretical basis for targeting H-type vessels to treat large femoral defects. STATEMENT OF SIGNIFICANCE: Abundant functional blood vessels are essential for bone repair. The H-type blood vessel is a functional subtype with angiogenesis and osteogenesis coupling potential. A drug loading system with long-term controlled release was first used to investigate the formation of H-type blood vessels in critical femoral defects and promotion of bone repair. Our results showed that the application of DFO-GMs hydrogel complex expanded the distribution range and expression time of H-type vessels, and was positively correlated with the number of osteoblasts and volume of new bone tissue. These results expanded the local application approach of DFO and provide a theoretical basis for targeting H-type vessels to treat large femoral defects.

Porous gelatin microsphere-based scaffolds containing MC3T3-E1 cells and calcitriol for the repair of skull defect

There is an increasing demand for biomaterials with skull regeneration for clinical application. However, most of the current skull repair materials still have limitations, such as inadequate sources, poor cell adherence, differentiation, tissue infiltration, and foreign body sensation. Therefore, this study developed porous microsphere-based scaffolds containing mouse embryonic osteoblast precursor cells (MC3T3-E1 cells) and calcitriol (Cal) using gelatin and gelatin/hydroxyapatite through green freeze-crosslinking and freeze-drying. Gelatin was employed to prepare porous microspheres with a particle size of 100-300 μm, containing open pores of 2-70 μm and interconnected paths. Furthermore, the addition of Cal to porous gelatin microsphere-based scaffolds containing MC3T3-E1 cells (PGMSs-MC) and porous gelatin/hydroxyapatite composite microspheres containing MC3T3-E1 cells (HPGMSs-MC) improved their osteoinductivity and cell proliferation and promoted the formation of mature and well-organized bone. The developed Cal-HPGMSs-MC and Cal-PGMSs-MC displayed a good porous structure and cytocompatibility, histocompatibility, osteoconductivity, and osteoinduction. Thus, the designed scaffolds provide a promising prospect for tissue-engineered constructs with skull growth and integration, laying a foundation for further research on the reconstruction of skull defects.

Non-destructive monitoring of 3D cell cultures: new technologies and applications

3D cell cultures are becoming the new standard for cell-based in vitro research, due to their higher transferrability toward in vivo biology. The lack of established techniques for the non-destructive quantification of relevant variables, however, constitutes a major barrier to the adoption of these technologies, as it increases the resources needed for the experimentation and reduces its accuracy. In this review, we aim at addressing this limitation by providing an overview of different non-destructive approaches for the evaluation of biological features commonly quantified in a number of studies and applications. In this regard, we will cover cell viability, gene expression, population distribution, cell morphology and interactions between the cells and the environment. This analysis is expected to promote the use of the showcased technologies, together with the further development of these and other monitoring methods for 3D cell cultures. Overall, an extensive technology shift is required, in order for monolayer cultures to be superseded, but the potential benefit derived from an increased accuracy of in vitro studies, justifies the effort and the investment.

Biomaterial Scaffolds Made of Chemically Cross-Linked Gelatin Microsphere Aggregates (C-GMSs) Promote Vascularized Bone Regeneration

Various scaffolding systems have been attempted to facilitate vascularization in tissue engineering by optimizing biophysical properties (e.g., vascular-like structures, porous architectures, surface topographies) or loading biochemical factors (e.g., growth factors, hormones). However, vascularization during ossification remains an unmet challenge that hampers the repair of large bone defects. In this study, reconstructing vascularized bones in situ against critical-sized bone defects is endeavored using newly developed scaffolds made of chemically cross-linked gelatin microsphere aggregates (C-GMSs). The rationale of this design lies in the creation and optimization of cell-material interfaces to enhance focal adhesion, proliferation, and function of anchorage-dependent functional cells. In vitro trials are carried out by coculturing human aortic endothelial cells (HAECs) and murine osteoblast precursor cells (MC3T3-E1) within C-GMS scaffolds, in which endothelialized bone-like constructs are yielded. Angiogenesis and osteogenesis induced by C-GMSs scaffold are further confirmed via subcutaneous-embedding trials in nude mice. In situ trials for the repair of critical-sized femoral defects are subsequently performed in rats. The acellular C-GMSs with interconnected macropores, exhibit the capability to recruit the endogenous cells (e.g., bone-forming cells, vascular forming cells, immunocytes) and then promote vascularized bone regeneration as well as integration with host bone.

Influence of substrate temperature parameter on electrospinning process: example of application to the formation of gelatin fibers

The substrate temperature was investigated to broaden the applicability of controlling the morphology of polymeric fibers produced during the electrospinning process. A laboratory electrospinning setup was designed using a substrate heated in a temperature range of 25 °C to 100 °C. A gelatin polymer was used as an example to obtain beads-free gelatin fibers by fixing the main electrospinning parameters. Based on XRD, FTIR, and DSC techniques, the electrospun gelatin fibers did not show any change in their chemical composition up to 100 °C. Heating the substrate at 50 °C may be the best selection factor to obtain gelatin fibers; the fiber diameters experienced a significant decrease from 680 ± 140 nm to 420 ± 120 nm with increasing substrate temperature from 25 to 50 °C, respectively. They showed stability of the diameter at 380 ± 130 nm and 390 ± 130 nm when increasing substrate temperatures from 75 to 100 °C, respectively, with a significant variation in their diameter distribution. Therefore, this ability to control the electrospinning process using a heated substrate makes it promising for fabricating electrospun beads-free fibers of biopolymers such as gelatin for tissue engineering and drug delivery carriers.

Inhibitory effect and mechanism of gelatin stabilized ferrous sulfide nanoparticles on porcine reproductive and respiratory syndrome virus

Background

The infection and spread of porcine reproductive and respiratory syndrome virus (PRRSV) pose a serious threat to the global pig industry, and inhibiting the viral infection process is a promising treatment strategy. Nanomaterials can interact with viruses and have attracted much attention due to their large specific surface area and unique physicochemical properties. Ferrous sulfide nanoparticles (FeS NPs) with the characteristics of high reactivity, large specific surface area, and low cost are widely applied to environmental remediation, catalysis, energy storage and medicine. However, there is no report on the application of FeS NPs in the antiviral field. In this study, gelatin stabilized FeS nanoparticles (Gel-FeS NPs) were large-scale synthesized rapidly by the one-pot method of co-precipitation of Fe²⁺ and S^2‒.

Results

The prepared Gel-FeS NPs exhibited good stability and dispersibility with an average diameter of 47.3 nm. Additionally, they were characterized with good biocompatibility and high antiviral activity against PRRSV proliferation in the stages of adsorption, invasion, and replication.

Conclusions

We reported for the first time the virucidal and antiviral activity of Gel-FeS NPs. The synthesized Gel-FeS NPs exhibited good dispersibility and biocompatibility as well as effective inhibition on PRRSV proliferation. Moreover, the Fe²⁺ released from degraded Gel-FeS NPs still displayed an antiviral effect, demonstrating the advantage of Gel-FeS NPs as an antiviral nanomaterial compared to other nanomaterials. This work highlighted the antiviral effect of Gel-FeS NPs and provided a new strategy for ferrous-based nanoparticles against PRRSV.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01281-4.

A Naringin-loaded gelatin-microsphere/nano-hydroxyapatite/silk fibroin composite scaffold promoted healing of critical-size vertebral defects in ovariectomised rat

In this study, we investigated the effect of three-dimensional of naringin/gelatin microspheres/nano-hydroxyapatite/silk fibroin (NG/GMs/nHA/SF) scaffolds on repair of a critical-size bone defect of lumbar 6 in osteoporotic rats. In this work, a cell-free scaffold for bone-tissue engineering based on a silk fibroin (SF)/nano-hydroxyapatite (nHA) scaffold was developed. The scaffold was fabricated by lyophilization. Naringin (NG) was loaded into gelatin microspheres (GMs), which were encapsulated in the nHA/SF scaffolds. The materials were characterized using x ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. Moreover, the biomechanics, degradation, and drug-release profile of the scaffold were also evaluated. In vitro, the effect of the scaffold on the adhesion, proliferation, and osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) was evaluated. In vivo, at 3 months after ovariectomy, a critical-size lumbar defect was indued in the rats to evaluate scaffold therapeutic potential. A 3-mm defect in L6 developed in 60 SD rats, which were randomly divided into SF scaffold, nHA/SF scaffold, NG/nHA/SF scaffold, NG/GMs/nHA/SF scaffold, and blank groups (n = 12 each). At 4, 8, 12, and 16 weeks postoperatively, osteogenesis was evaluated by X-ray, micro-computed tomography, hematoxylin-eosin staining, and fast green staining, and by analysis of BMP-2, Runx2, and Ocn protein levels at 16 weeks. In our results, NG/GM/nHA/SF scaffolds exhibited good biocompatibility, biomechanical strength, and promoted BMSC adhesion, proliferation, and calcium nodule formation in vitro. Moreover, NG/GMs/nHA/SF scaffolds showed greater osteogenic differentiation potential than the other scaffolds in vitro. In vivo, gradual new bone formation was observed, and bone defects recovered by 16 weeks in the experimental group. In the blank group, limited bone formation was observed, and the bone defect was obvious. In conclusion, NG/GMs/nHA/SF scaffolds promoted repair of a lumbar 6 defect in osteoporotic rats. Therefore, the NG/GMs/nHA/SF biocomposite scaffold has potential as a bone-defect-filling biomaterial for bone regeneration.

Gelatin-Based Hybrid Scaffolds: Promising Wound Dressings

Wound care is a major biomedical field that is challenging due to the delayed wound healing process. Some factors are responsible for delayed wound healing such as malnutrition, poor oxygen flow, smoking, diseases (such as diabetes and cancer), microbial infections, etc. The currently used wound dressings suffer from various limitations, including poor antimicrobial activity, etc. Wound dressings that are formulated from biopolymers (e.g., cellulose, chitin, gelatin, chitosan, etc.) demonstrate interesting properties, such as good biocompatibility, non-toxicity, biodegradability, and attractive antimicrobial activity. Although biopolymer-based wound dressings display the aforementioned excellent features, they possess poor mechanical properties. Gelatin, a biopolymer has excellent biocompatibility, hemostatic property, reduced cytotoxicity, low antigenicity, and promotes cellular attachment and growth. However, it suffers from poor mechanical properties and antimicrobial activity. It is crosslinked with other polymers to enhance its mechanical properties. Furthermore, the incorporation of antimicrobial agents into gelatin-based wound dressings enhance their antimicrobial activity in vitro and in vivo. This review is focused on the development of hybrid wound dressings from a combination of gelatin and other polymers with good biological, mechanical, and physicochemical features which are appropriate for ideal wound dressings. Gelatin-based wound dressings are promising scaffolds for the treatment of infected, exuding, and bleeding wounds. This review article reports gelatin-based wound dressings which were developed between 2016 and 2021.

Biopolymers Hybrid Particles Used in Dentistry

This literature review provides an overview of the fabrication and application of biopolymer hybrid particles in dentistry. A total of 95 articles have been included in this review. In the review paper, the common inorganic particles and biopolymers used in dentistry are discussed in general, and detailed examples of inorganic particles (i.e., hydroxyapatite, calcium phosphate, and bioactive glass) and biopolymers such as collagen, gelatin, and chitosan have been drawn from the scientific literature and practical work. Among the included studies, calcium phosphate including hydroxyapatite is the most widely applied for inorganic particles used in dentistry, but bioactive glass is more applicable and multifunctional than hydroxyapatite and is currently used in clinical practice. Today, biopolymer hybrid particles are receiving more attention as novel materials for several applications in dentistry, such as drug delivery systems, bone repair, and periodontal regeneration surgery. The literature published on the biopolymer gel-assisted synthesis of inorganic particles for dentistry is somewhat limited, and therefore, this article focuses on reviewing and discussing the biopolymer hybrid particles used in dentistry.