An epidermal growth factor receptor-targeting immunotoxin based on IgG shows potent antitumor activity against head and neck cancer.

The epidermal growth factor receptor (EGFR) is an important target for cancer therapies. Many head and neck cancer (HNC) cells have been reported to overexpress EGFR; therefore, anti-EGFR therapies have been attempted in patients with HNC. However, its clinical efficacy is limited owing to the development of drug resistance. In this study, we developed an EGFR-targeting immunotoxin consisting of a clinically proven anti-EGFR IgG (cetuximab; CTX) and a toxin fragment (LR-LO10) derived from Pseudomonas exotoxin A (PE) using a novel site-specific conjugation technology (peptide-directed photo-crosslinking reaction), as an alternative option. The immunotoxin (CTX-LR-LO10) showed specific binding to EGFR and properties of a typical IgG, such as stability, interactions with receptors of immune cells, and pharmacokinetics, and inhibited protein synthesis via modification of elongation factor-2. Treatment of EGFR-positive HNC cells with the immunotoxin resulted in apoptotic cell death and the inhibition of cell migration and invasion. The efficacy of CTX-LR-LO10 was evaluated in xenograft mouse models, and the immunotoxin exhibited much stronger tumor suppression than CTX or LR-LO10. Transcriptome analyses revealed that the immunotoxins elicited immune responses and altered the expression of genes related to its mechanisms of action. These results support the notion that CTX-LR-LO10 may serve as a new therapeutic agent targeting EGFR-positive cancers.

Spatiotemporally Controllable Covalent Bonding of RNA for Multi-Protein Interference.

Many diseases are associated with genetic mutation and expression of mutated proteins, such as cancers. Therapeutic approaches that selectively target the synthesis process of multiple proteins show greater potential compared to single-protein approaches in oncological diseases. However, conventional agents to regulate the synthesis of multiple protein still suffer from poor spatiotemporal selectivity and stability. Here, a new method using a dye-peptide conjugate, PRFK, for multi-protein interference with spatiotemporal selectivity and reliable stability, is reported. By using the peptide sequence that targets tumor cells, PRFK can be efficiently taken up, followed by specific binding to the KDELR (KDEL receptor) protein located in the endoplasmic reticulum (ER). The dye generates 1O2 under light irradiation, enabling photodynamic therapy. This process converts the furan group into a cytidine-reactive intermediate, which covalently binds to mRNA, thereby blocking protein synthesis. Upon treating 4T1 cells, the proteomics data show alterations in apoptosis, ferroptosis, proliferation, migration, invasion, and immune infiltration, suggesting that multi-protein interference leads to the disruption of cellular physiological activities, ultimately achieving tumor treatment. This study presents a multi-protein interference probe with the potential for protein interference within various subcellular organelles in the future.

Functionally graded hydrogels with opposing biochemical cues for osteochondral tissue engineering.

Osteochondral tissue (OC) repair remains a significant challenge in the field of musculoskeletal tissue engineering. OC tissue displays a gradient structure characterized by variations in both cell types and extracellular matrix components, from cartilage to the subchondral bone. These functional gradients observed in the native tissue have been replicated to engineer OC tissuein vitro. While diverse fabrication methods have been employed to create these microenvironments, emulating the natural gradients and effective regeneration of the tissue continues to present a significant challenge. In this study, we present the design and development of CMC-silk interpenetrating (IPN) hydrogel with opposing dual biochemical gradients similar to native tissue with the aim to regenerate the complete OC unit. The gradients of biochemical cues were generated using an in-house-built extrusion system. Firstly, we fabricated a hydrogel that exhibits a smooth transition of sulfated carboxymethyl cellulose (sCMC) and TGF-ß1 (SCT gradient hydrogel) from the upper to the lower region of the IPN hydrogel to regenerate the cartilage layer. Secondly, a hydrogel with a hydroxyapatite (HAp) gradient (HAp gradient hydrogel) from the lower to the upper region was fabricated to facilitate the regeneration of the subchondral bone layer. Subsequently, we developed a dual biochemical gradient hydrogel with a smooth transition of sCMC + TGF-ß1 and HAp gradients in opposing directions, along with a blend of both biochemical cues in the middle. The results showed that the dual biochemical gradient hydrogels with biochemical cues corresponding to the three zones (i.e. cartilage, interface and bone) of the OC tissue led to differentiation of bone-marrow-derived mesenchymal stem cells to zone-specific lineages, thereby demonstrating their efficacy in directing the fate of progenitor cells. In summary, our study provided a simple and innovative method for incorporating gradients of biochemical cues into hydrogels. The gradients of biochemical cues spatially guided the differentiation of stem cells and facilitated tissue growth, which would eventually lead to the regeneration of the entire OC tissue with a smooth transition from cartilage (soft) to bone (hard) tissues. This promising approach is translatable and has the potential to generate numerous biochemical and biophysical gradients for regeneration of other interface tissues, such as tendon-to-muscle and ligament-to-bone.

Surfactant-assisted photo-crosslinked silk fibroin sponges: A versatile platform for the design of bone scaffolds.

Critical size bone defects cannot heal without aid and current clinical approaches exhibit some limitations, underling the need for novel solutions. Silk fibroin, derived from silkworms, is widely utilized in tissue engineering and regenerative medicine due to its remarkable properties, making it a promising candidate for bone tissue regeneration in vitro and in vivo. However, the clinical translation of silk-based materials requires refinements in 3D architecture, stability, and biomechanical properties. In earlier research, improved mechanical resistance and stability of chemically crosslinked methacrylate silk fibroin (Sil-Ma) sponges over physically crosslinked counterparts were highlighted. Furthermore, the influence of photo-initiator and surfactant concentrations on silk properties was investigated. However, the characterization of sponges with Sil-Ma solution concentrations above 10 % (w/V) was hindered by production optimization challenges, with only cell viability assessed. This study focuses on the evaluation of methacrylate sponges' suitability as temporal bone tissue regeneration scaffolds. Sil-Ma sponge fabrication at a fixed concentration of 20 % (w/V) was optimized and the impact of photo-initiator (LAP) concentrations and surfactant (Tween 80) presence/absence was studied. Their effects on pore formation, silk secondary structure, mechanical properties, and osteogenic differentiation of hBM-MSCs were investigated. We demonstrated that, by tuning silk sponges' composition, the optimal combination boosted osteogenic gene expression, offering a strategy to tailor biomechanical properties for effective bone regeneration. Utilizing Design of Experiment (DoE), correlations between sponge composition, porosity, and mechanical properties are established, guiding tailored material outcomes. Additionally, correlation matrices elucidate the microstructure's influence on gene expressions, providing insights for personalized approaches in bone tissue regeneration.

Preparation of an injectable and photocurable carboxymethyl cellulose/hydroxyapatite composite and its application in cranial regeneration.

Limited bone regeneration, uncontrollable degradation rate, mismatched defect zone and poor operability have plagued the reconstruction of irregular bone defect by tissue-engineered materials. A combination of biomimetic scaffolds with hydroxyapatite has gained great popularity in promoting bone regeneration. Therefore, we designed an injectable, photocurable and in-situ curing hydrogel by methacrylic anhydride -modified carboxymethyl cellulose (CMC-MA) loading with spherical hydroxyapatite (HA) to highly simulate the natural bony matrix and match any shape of damaged tissue. The prepared carboxymethyl cellulose-methacrylate/ hydroxyapatite(CMC-MA/HA) composite presented good rheological behavior, swelling ratio and mechanical property under light illumination. Meanwhile, this composite hydrogel promoted effectively proliferation, supported adhesion and upregulated the osteogenic-related genes expression of MC3T3-E1 cells in vitro, as well as the activity of the osteogenic critical protein, Integrin α1, ß1, Myosin 9, Myosin 10, BMP-2 and Smad 1 in Integrin/BMP-2 signal pathway. Together, the composite hydrogels realized promotion of bone regeneration, deformity improvement, and the enhanced new bone strength in skull defect. It also displayed a good histocompatibility and stability of subcutaneous implantation in vivo. Overall, this study laid the groundwork for future research into developing a novel biomaterial and a minimally invasive therapeutic strategies for reconstructing bone defects and contour deficiencies.

A controlled light-induced gas-foaming porous hydrogel with adhesion property for infected wound healing.

Porous hydrogels as scaffolds have great potential in tissue engineering. However, there are still challenges in preparing porous hydrogels with tunable pore size and controlled porosity. Here, we successfully established a photoinduced gas-foaming method of porous hydrogels with controlled macro-micro-nano multiscale. A diazirine (DZ)-modified gelatin (GelDZ) biomaterial was prepared by introducing photocrosslinked DZ group into gelatin. Upon exposure to 365 nm UV light, DZ could be converted to the active group carbene, which could randomly insert into OH, NH, or CH bonds to form covalent crosslinks. GelDZ generated N2 by photodegradation and formed gas-induced porous hydrogels by intermolecular crosslinking without initiator. The loose porous structure of the hydrogel can promote the infiltration of host cells and blood vessels, which was conducive to tissue repair. The interfacial crosslinking of photoactivated GelDZ with tissue proteins imparted adhesion properties to the hydrogel. GelDZ also possessed photoreduction ability, which can reduce silver ions from metal precursors to silver nanoparticles (Ag NPs) in situ, and showed great antibacterial activity due to the sustained release of Ag NPs. GelDZ-Ag NPs prepared by in situ photoreaction can effectively inhibit wound infection and promote skin wound healing, providing a new strategy for designing porous hydrogel in tissue engineering.

Effect of Residue Acrylic Monomers in Synthesized Solvent-Free Photoreactive Pressure-Sensitive Adhesives on the Main Properties of Transfer Tapes Applied to Joining Wooden Elements.

This publication describes the influence of residue monomers in synthesized pressure-sensitive adhesives based on acrylics on their main properties-tack, peel adhesion, shear strength and shrinkage-in the form of transfer tapes used for joining wooden elements in the furniture industry. The discussed carrier-free adhesive tapes are synthesized via photo-crosslinking and photopolymerization with UV radiation of the photoreactive prepolymers sandwiched between two adhesive siliconized polyester films. The simultaneous crosslinking and polymerization processes carried out under UV lamps placed simultaneously above and below the crosslinked photoreactive polymer layer lead to the production of a carrier-free adhesive film. The preliminary target of these studies was to investigate how the intensity of UV radiation and the time of its exposure affect the viscosity of the photoreactive compositions and the content of unreacted monomers in them. Next, the influence of the crosslinking agent concentration and UV irradiation time on the content of unreacted monomers after the crosslinking process was tested. The last step of the studies was the investigation of the influence of the residue monomer concentration on the application properties of the obtained pressure-sensitive adhesive layers. The typical PSA application properties were tested on the wood samples: tack, peel adhesion, shear strength (cohesion) and shrinkage.

In situ photo-crosslinkable hyaluronic acid-based hydrogel embedded with GHK peptide nanofibers for bioactive wound healing.

A versatile hydrogel was developed for enhancing bioactive wound healing by introducing the amphiphilic GHK peptide (GHK-C16) into a photo-crosslinkable tyramine-modified hyaluronic acid (HA-Ty). GHK-C16 self-assembled into GHK nanofibers (GHK NF) in HA-Ty solution, which underwent in situ gelation after the wound area was filled with precursor solution. Blue light irradiation (460-490 nm), with riboflavin phosphate as a photoinitiator, was used to trigger crosslinking, which enhanced the stability of the highly degradable hyaluronic acid and enabled sustained release of the nanostructured GHK derivatives. The hydrogels provided a microenvironment that promoted the proliferation of dermal fibroblasts and the activation of cytokines, leading to reduced inflammation and increased collagen expression during wound healing. The complexation of Cu2+ into GHK nanofibers resulted in superior wound healing capabilities compared with non-lipidated GHK peptide with a comparable level of growth factor (EGF). Additionally, nanostructured Cu-GHK improved angiogenesis through vascular endothelial growth factor (VEGF) activation, which exerted a synergistic therapeutic effect. Furthermore, in vivo wound healing experiments revealed that the Cu-GHK NF/HA-Ty hydrogel accelerated wound healing through densely packed remodeled collagen in the dermis and promoting the growth of denser fibroblasts. HA-Ty hydrogels incorporating GHK NF also possessed improved mechanical properties and a faster wound healing rate, making them suitable for advanced bioactive wound healing applications. STATEMENT OF SIGNIFICANCE: By combining photo-crosslinkable tyramine-modified hyaluronic acid with self-assembled Cu-GHK-C16 peptide nanofibers (Cu-GHK NF), the Cu-GHK NF/HA-Ty hydrogel offers remarkable advantages over conventional non-structured Cu-GHK for wound healing. It enhances cell proliferation, migration, and collagen remodeling-critical factors in tissue regeneration. The incorporation of GHK nanofibers complexed with copper ions imparts potent anti-inflammatory effects, promoting cytokine activation and angiogenesis during wound healing. The Cu-GHK NF/hydrogel's unique properties, including in situ photo-crosslinking, ensure high customization and potency in tissue regeneration, providing a cost-effective alternative to growth factors. In vivo experiments further validate its efficacy, demonstrating significant wound closure, collagen remodeling, and increased fibroblast density. Overall, the Cu-GHK NF/HA-Ty hydrogel represents an advanced therapeutic option for wound healing applications.

Construction and Catalytic Study of Affinity Peptide Orientation and Light Crosslinking Immobilized Sucrose Isomerase.

A novel affinity peptide orientation and light-controlled covalent immobilized method was developed. Sucrose isomerase (SI) was selected as the model enzyme. Molecular simulation was first performed to select the targeted immobilization region. Subsequently, a short peptide (H2N-VNIGGX-COOH, VG) with high affinity to this region was rationally designed. Thereafter, 4-benzoyl-l-phenylalanine with the photosensitive group of benzophenone was introduced. Then, the affinity between the ligand and the SI was validated using molecular dynamics simulation. Thereafter, the SI was directionally immobilized onto the surface of the epoxy resin (EP) guided by VG via photo-crosslinking, and thus the oriented photo-crosslinking enzymes were obtained. The enzymatic activity, thermostability, and reusability of the affinity directional photo-crosslinked immobilized sucrose isomerase (hv-EP-VG-SI) were systematically studied. The oriented immobilization enzymes were significantly improved in recycling and heat resistance. Moreover, hv-EP-VG-SI retained more than 90% of the original activity and 50% of the activity after 11 cycles.

A photo-activable nano-agonist for the two-signal model of T cell in vivo activation.

The two-signal model of T cell activation has helped shape our understanding of the adaptive immune response for over four decades. According to the model, activation of T cells requires a stimulus through the T cell receptor/CD3 complex (signal 1) and a costimulatory signal 2. Stimulation of activatory signals via T cell agonists has thus emerged. However, for a robust T cell activation, it necessitates not only the presence of both signal 1 and signal 2, but also a high signaling strength. Herein, we report a photo-activable nano-agonist for the two-signal model of T cell in vivo activation. A UV-crosslinkable polymer is coated onto upconversion nanoparticles with satisfactory NIR-to-UV light conversion efficiency. Then dual signal molecules, i.e., signal 1 and signal 2, are conjugated to the polymer end to yield the photo-activable T cell nano-agonist. In melanoma and breast cancer models, photo-activable nano-agonist could bind onto corresponding activatory receptors on the surface of T cells, but has limited activity without the application of NIR light (absence of photo-crosslinking of receptors and consequently a poor signaling strength). While when the NIR light is switched on locally, T cells in tumor are remarkably activated and kill tumor cells effectively. Moreover, we do not observe any detectable toxicities related to the photo-activable nano-agonist. We believe with two activatory signals being simultaneously strengthened by local photo-switched crosslinking, T cells realize a robust and selective activation in tumor and, consequently contribute to an enhanced and safe tumor immunotherapy.

Enzymatic post-crosslinking of printed hydrogels of methacrylated gelatin and tyramine-conjugated 8-arm poly(ethylene glycol) to prepare interpenetrating 3D network structures.

Methacrylated gelatin (GelMA) has been intensively studied as a 3D printable scaffold material in tissue regeneration fields, which can be attributed to its well-known biological functions. However, the long-term stability of photo-crosslinked GelMA scaffolds is hampered by a combination of its fast degradation in the presence of collagenase and the loss of physical crosslinks at higher temperatures. To increase the longer-term shape stability of printed scaffolds, a mixture of GelMA and tyramine-conjugated 8-arm PEG (8PEGTA) was used to create filaments composed of an interpenetrating network (IPN). Photo-crosslinking during filament deposition of the GelMA and subsequent enzymatic crosslinking of the 8PEGTA were applied to the printed 3D scaffolds. Although both crosslinking mechanisms are radical based, they operate without interference of each other. Rheological data of bulk hydrogels showed that the IPN was an elastic hydrogel, having a storage modulus of 6 kPa, independent of temperature in the range of 10 - 40°C. Tensile and compression moduli were 110 kPa and 80 kPa, respectively. On enzymatic degradation in the presence of collagenase, the gelatin content of the IPN fully degraded in 7 days, leaving a stable secondary crosslinked 8PEGTA network. Using a BioMaker bioprinter, hydrogels without and with human osteosarcoma cells (hMG-63) were printed. On culturing for 21 days, hMG-63 in the GelMA/8PEGTA IPN showed a high cell viability (>90%). Thus, the presence of the photoinitiator, incubation with H2O2, and mechanical forces during printing did not hamper cell viability. This study shows that the GelMA/8PEGTA ink is a good candidate to generate cell-laden bioinks for extrusion-based printing of constructs for tissue engineering applications.

Photo-crosslinking hydrogel for wound healing in a pilonidal sinus patient after open surgery.

Pilonidal sinus is a chronic infectious disease with large incision and high risk of relapse after surgical management. Therefore, effective intervention strategies are urgently needed to reduce the relapse and shorten the wound healing time. Hydrogels have been widely used in regenerative medicine for its great biocompatibility, however, it remains challenging to integrate the material with wound tissues. Here, we reported a case of pilonidal sinus patient using a novel tissue integration material, Photo-crosslinking hydrogel after open surgery. A 38-year-old man with a pilonidal sinus for ˃5 years underwent open surgery. When the surgery was finished, the wound was injected with hydrogel that was irradiated with a ultraviolet light source until covered and solidified completely. Hydrogel needed to be changed 1-2 times per week. We evaluated the healing time as primary outcome and then followed up for ˃1 year to observe the relapse. The wound healed completely in 46 days after open surgery, which was shorter than that reported in other studies. Meanwhile, no recurrence was detected during follow-up. Photo-crosslinking hydrogel effectively promoted wound healing and has the potential to be easily applied in Pilonidal sinus patients after open surgery.

Analyzing the interactome of human CK2ß in prostate carcinoma cells reveals HSP70-1 and Rho guanin nucleotide exchange factor 12 as novel interaction partners.

CK2ß is the non-catalytic modulating part of the S/T-protein kinase CK2. However, the overall function of CK2ß is poorly understood. Here, we report on the identification of 38 new interaction partners of the human CK2ß from lysates of DU145 prostate cancer cells using photo-crosslinking and mass spectrometry, whereby HSP70-1 was identified with high abundance. The KD value of its interaction with CK2ß was determined as 0.57 µM by microscale thermophoresis, this being the first time, to our knowledge, that a KD value of CK2ß with another protein than CK2α or CK2α' was quantified. Phosphorylation studies excluded HSP70-1 as a substrate or activity modulator of CK2, suggesting a CK2 activity independent interaction of HSP70-1 with CK2ß. Co-immunoprecipitation experiments in three different cancer cell lines confirmed the interaction of HSP70-1 with CK2ß in vivo. A second identified CK2ß interaction partner was Rho guanin nucleotide exchange factor 12, indicating an involvement of CK2ß in the Rho-GTPase signal pathway, described here for the first time to our knowledge. This points to a role of CK2ß in the interaction network affecting the organization of the cytoskeleton.

Extracellular matrix bioink boosts stemness and facilitates transplantation of intestinal organoids as a biosafe Matrigel alternative.

Organoids hold inestimable therapeutic potential in regenerative medicine and are increasingly serving as an in vitro research platform. Still, their expanding applications are critically restricted by the canonical culture matrix and system. Synthesis of a suitable bioink of bioactivity, biosecurity, tunable stiffness, and printability to replace conventional matrices and fabricate customized culture systems remains challenging. Here, we envisaged a novel bioink formulation based on decellularized extracellular matrix (dECM) from porcine small intestinal submucosa for organoids bioprinting, which provides intestinal stem cells (ISCs) with niche-specific ECM content and biomimetic microstructure. Intestinal organoids cultured in the fabricated bioink exhibited robust generation as well as a distinct differentiation pattern and transcriptomic signature. This bioink established a new co-culture system able to study interaction between epithelial homeostasis and submucosal cells and promote organoids maturation after transplantation into the mesentery of immune-deficient NODSCID-gamma (NSG) mice. In summary, the development of such photo-responsive bioink has the potential to replace tumor-derived Matrigel and facilitate the application of organoids in translational medicine and disease modeling.

An interplay of matrix stiffness, dimensionality and adhesivity on cellular behavior.

Cell-based assays are essentialin vitrotools for understanding basic cell biology, pathophysiology of diseases and mechanism of drug actions most cancer studies have utilized two-dimensional (2D) cell culture methods, which have their shortcomings including lack of cell- extracellular matrix interactions and three-dimensional (3D) geometry, and inaccurate representation of cell polarity. Hence, 3D matrices are being increasingly used to study the effect of 3D niche on cell behavior. Till date, very few systematic studies have been done to show comparison of cell behavior when seeded on the surface and encapsulated inside the matrix. In this study, we fabricated poly(ethylene glycol) (PEG) and gelatin-based matrices using UV mediated photo-polymerization to establish 2D and 3D cell culture methods using breast cancer MDA-MB-231 cells. We have found that the adhesion and spreading of cells on the gel surface is different from that when embedded in gels. The stiffness of poly (ethylene glycol) diacrylate (PEGDA)-gelatin methacryloyl (GelMA) hydrogels with lower concentration of GelMA is lower than that with higher GelMA; further, those with higher overall concentration of polymers (>5%) retain their mechanical integrity and do not degrade even after 7 d. Physical characterization of these matrices demonstrate their optimal pore size, mechanical stiffness and degradation, which are further tunable for tissue engineering, regenerative medicine, drug delivery and cancer studies. Additionally, these semi-synthetic PEGDA-GelMA matrices are transparent in nature, thereby, allowing easy imaging of cells in 3D. The system developed here can be used for short and long term cell culture and can be potentially explored for cell migration and metastasis studies.

Pinpointing the interaction site between semaphorin-3A and its inhibitory peptide.

Semaphorin-3A (Sema-3A) is a chemorepellant protein with various biological functions, including kidney development. It interacts with a protein complex consisting of the receptors neuropilin-1 (NRP-1) and plexin-A1. After acute kidney injury, Sema-3A is overexpressed and secreted, leading to a loss of kidney function. The development of peptide inhibitors is a promising approach to modulate the interaction of Sema-3A with its receptor NRP-1. Few interaction points between these binding partners are known. However, an immunoglobulin-like domain-derived peptide of Sema-3A has shown a positive effect on cell proliferation. To specify these interactions between the peptide inhibitor and the Sema-3A-NRP-1 system, the peptides were modified with the photoactivatable amino acids 4-benzoyl-l-phenylalanine or photo-l-leucine by solid-phase peptide synthesis. Activity was tested by an enzyme-linked immunosorbent-based binding assay, and crosslinking experiments were analyzed by Western blot and mass spectrometry, demonstrating a specific binding site of the peptide at Sema-3A. The observed signals for Sema-3A-peptide interaction were found in a defined area of the Sema domain, which was also demonstrated to be involved in NRP-1 binding. The presented data identified the interaction site for further development of therapeutic peptides to treat acute kidney injury by blocking the Sema-3A-NRP-1 interaction.

User-demand fast-curable ocular glues enforced by multilength tunable networks.

Achieving fast and secure wound closure without ocular foreign body sensation is highly desired in ophthalmologic surgery. Sutureless approaches using tissue adhesives are gaining popularity, but their practical use is limited by the difficulty in controlling adhesion time and satisfying safety standards without compromising adhesive performance. Herein, we report user-demand hydrogel-forming ocular glues based on multilength photo-crosslinkable hyaluronic acid (HA), achieving firm tissue adhesion under wet and dynamic conditions and possessing cornea-like optical transparency. The HA-based photocurable glue (HA photoglue) quickly seals wounds upon nontoxic low-energy light exposure (320-500 nm, < 5 s, < 1 J cm-2), and its mechanical and adhesive properties are improved by introducing short and long crosslinkable moieties into HA through one-step synthesis, forming multilength networks. Furthermore, the HA photoglue provides stable sealing in wet environments like ocular mucous surface, a clear vision with a light transmittance of more than 95% over the entire visible range, and a lubricating surface with minimal ocular sensation (generating less than 10% frictional force than suture groups). In a rabbit corneal incision model, the HA photoglue showed improved wound healing efficacy based on histological evaluation compared to control groups.

Facile synthesis of chitosan-based nanogels through photo-crosslinking for doxorubicin delivery.

Chitosan-based nanogels are effective carriers for drug delivery due to their biocompatibility and biodegradability. However, the chemically cross-linked nanogels usually require complicated procedures or tough conditions. Herein, we report a simple approach to generate chitosan-based nanogels by photo-crosslinking of poor solvent-induced nanoaggregates without requiring any emulsifying agent, catalyst, or external crosslinker. O-nitrobenzyl alcohol-modified carboxymethyl chitosan was synthesized and self-crosslinked into the nanogels in a mixed solution of ethanol and water under 365 nm light irradiation due to UV-induced primary amine and o-nitrobenzyl alcohol cyclization. The nanogels (CMC-NBA NPs) and lactobionic acid-decorated nanogels (LACMC-NBA NPs) displayed a uniform diameter (~200 nm) and excellent stability under physiological conditions. Notably, the nanogels exhibited a high loading content (~28 %) due to π-π stacking and electrostatic interactions between doxorubicin (DOX) and the carriers. These DOX-loaded nanogels showed rapid drug release under slightly acidic conditions. The cell and animal experiments confirmed that LACMC-NBA NPs increased cellular uptake, improved cytotoxicity in tumor cells, and enhanced growth inhibition in vivo than CMC-NBA NPs. Thus, these photo-crosslinked nanogels possess great potential for DOX delivery.

Robust gelatin hydrogels for local sustained release of bupivacaine following spinal surgery.

Adequate treatment of pain arising from spinal surgery is a major clinical challenge. Opioids are the mainstay of current treatment methods, but the frequency and severity of their side effects display a clear need for opioid-free analgesia. Local anesthetics have been encapsulated into sustained-release drug delivery systems to provide postoperative pain relief. However, these formulations are limited by rapid diffusion out of the surgical site. To overcome this limitation, we synthesized ring-shaped hydrogels incorporating bupivacaine, designed to be co-implanted with pedicle screws during spinal surgery. Hydrogels were prepared by riboflavin-mediated crosslinking of gelatin functionalized with tyramine moieties. Additionally, oxidized ß-cyclodextrin was introduced into the hydrogel formulation to form dynamic bonds with tyramine functionalities, which enables self-healing behavior and resistance to shear. Feasibility of hydrogel implantation combined with pedicle screws was qualitatively assessed in cadaveric sheep as a model for instrumented spinal surgery. The in-situ crystallization of bupivacaine within the hydrogel matrix provided a moderate burst decrease and sustained release that exceeded 72 hours in vitro. The use of bupivacaine crystals decreased drug-induced cytotoxicity in vitro compared to bupivacaine HCl. Thus, the presented robust hydrogel formulation provides promising properties to enable the stationary release of non-opioid analgesics following spinal surgery. STATEMENT OF SIGNIFICANCE: Currently, postoperative pain following spinal surgery is mainly treated with opioids. However, the use of opioids is associated with several side effects including addiction. Here we developed robust and cytocompatible gelatin hydrogels, prepared via riboflavin-mediated photocrosslinking, that can withstand orthopedic implantation. The implantability was confirmed in cadaveric instrumented spinal surgery. Further, hydrogels were loaded with bupivacaine crystals to provide sustained release beyond 72 hours in vitro. The use of crystallized bupivacaine decreased cytotoxicity compared to bupivacaine HCl. The present formulation can aid in enabling opioid-free analgesia following instrumented spinal surgery.

Photo Cross-linkable Biopolymers for Cornea Tissue Healing.

Light can act as an effective and strong agent for the cross-linking of biomaterials and tissues and is recognized as a safe substitute for chemical cross-linkers to modify mechanical and physical properties and promote biocompatibility. This review focuses on the research about crosslinked biomaterials with different radiation sources such as Laser or ultraviolet (UV) that can be applied as scaffolds, controlled release systems,and tissue adhesives for cornea healing and tissue regeneration.