In situ cross-linkable high molecular weight hyaluronan-bisphosphonate conjugate for localized delivery and cell-specific targeting: a hydrogel linked prodrug approach

N-Rich, Polyphenolic Porous Organic Polymer and Its In Vitro Anticancer Activity on Colorectal Cancer

N-rich organic materials bearing polyphenolic moieties in their building networks and nanoscale porosities are very demanding in the context of designing efficient biomaterials or drug carriers for the cancer treatment. Here, we report the synthesis of a new triazine-based secondary-amine- and imine-linked polyphenolic porous organic polymer material TrzTFPPOP and explored its potential for in vitro anticancer activity on the human colorectal carcinoma (HCT 116) cell line. This functionalized (-OH, -NH-, -C=N-) organic material displayed an exceptionally high BET surface area of 2140 m2 g-1 along with hierarchical porosity (micropores and mesopores), and it induced apoptotic changes leading to high efficiency in colon cancer cell destruction via p53-regulated DNA damage pathway. The IC30, IC50, and IC70 values obtained from the MTT assay are 1.24, 3.25, and 5.25 μg/mL, respectively.

Hyaluronan network: a driving force in cancer progression

Hyaluronan is one of the most abundant macromolecules of the extracellular matrix and regulates several physiological cell and tissue properties. However, hyaluronan has been shown to accumulate together with its receptors in various cancers. In tumors, accumulation of hyaluronan system components (hyaluronan synthesizing/degrading enzymes and interacting proteins) associates with poor outcomes of the patients. In this article, we review the main roles of hyaluronan in normal physiology and cancer, and further discuss the targeting of hyaluronan system as an applicable therapeutic strategy.

Hybrid in situ- forming injectable hydrogels for local cancer therapy

Injectable in situ forming hydrogels are amongst the efficient local drug delivery systems for cancer therapy. Providing a 3D hydrogel network within the target tissue capable of sustained release of the chemotherapeutics made them attractive candidates for increasing the therapeutic index. Remarkable swelling properties, mechanical strength, biocompatibility, wide composition variety and tunable polymeric moieties have led to preparation of injectable hydrogels which also could be used as cavity adaptive chemotherapeutic-loaded implants to prevent post -surgical cancer recurrence. Implementation of various polymers, nanoparticles, peptide and proteins and different crosslinking chemistry facilitated the fabrication of hybrid hydrogels with favorable characteristics such as stimuli sensitive platforms or multifunctional systems. In the current review, we focused on design and fabrication strategies of injectable in situ forming hydrogels and summarized recent hybrid hydrogels used for local cancer therapy.

New Progress in Improving the Delivery Methods of Bisphosphonates in the Treatment of Bone Tumors

Bone tumors are tumors that occur in the bone or its accessory tissues, including primary tumors and metastatic tumors. The main mechanism of bisphosphonate is to inhibit the resorption of destructive bone, inhibit the activity of osteoclasts and reduce the concentration of blood calcium. Therefore, bisphosphonates can be used for malignant hypercalcaemia, pain caused by osteolytic bone metastasis, prevention of osteolytic bone metastasis, multiple myeloma osteopathy, improving radiosensitivity and so on. However, the traditional administration of bisphosphonates can cause a series of adverse reactions. To overcome this disadvantage, it is necessary to develop novel methods to improve the delivery of bisphosphonates. In this paper, the latest research progress of new and improved bisphosphonate drug delivery methods in the treatment of bone tumors is reviewed. At present, the main design idea is to connect bisphosphonate nanoparticles, liposomes, microspheres, microcapsules, couplings, prodrugs and bone tissue engineering to targeted anti-tumors systems, and positive progress has been made in in vitro and animal experiments. However, its safety and effectiveness in human body still need to be verified by more studies.

Regulation of aquaporin-3 water permeability by hyaluronan

Hyaluronan (HA) is a major component in the extracellular matrix and is responsible for maintaining the water content of the skin. However, the function and moisturizing mechanism at the atomic level of HA remain only partially understood. Investigating the interactions of HA and other skin components can help us understand how the former moisturizes the skin. Considering that aquaporin-3 (AQP3) is a protein responsible for transmembrane water transport in the human skin, we have, therefore, investigated the interactions of AQP3 and HA with different molecular weights using molecular dynamics simulations in the present work. Our results indicate that HA can adsorb onto AQP3 and decrease water mobility around the latter. In addition, the permeation rate of water through AQP3 can also be decreased by HA, and this phenomenon is particularly obvious for small molecular HA. Moreover, we found that large molecular HA can link two adjacent membranes in the extracellular matrix, increasing the adhesion between the membranes in the periplasm. The results of the present study indicate that HA is a natural regulator of AQP3, revealing the synergetic function of HA and AQP3 in the extracellular matrix of the skin.

Differentiating Co-Delivery of Bisphosphonate and Simvastatin by Self-Healing Hyaluronan Hydrogel Formed by Orthogonal "Clicks": An In-Vitro Assessment

Due to its unique properties resembling living tissues, hydrogels are attractive carriers for the localized and targeted delivery of various drugs. Drug release kinetics from hydrogels are commonly controlled by network properties and the drug-network interactions. However, and simultaneously, the programmable delivery of multiple drugs with opposing properties (hydrophilicity, molecular weight, etc.) from hydrogels with determined network properties is still challenging. Herein, we describe the preparation of injectable self-healing hyaluronic acid (HA) hydrogels that release hydrophobic simvastatin and hydrophilic aminobisphosphonate (BP) drugs independently in response to acidic and thiol-containing microenvironments, respectively. We apply a prodrug strategy to BP by conjugating it to HA via a self-immolative disulfide linker that is stable in the blood plasma and is cleavable in the cytoplasm. Moreover, we utilize HA-linked BP ligands to reversibly bind Ca²⁺ ions and form coordination hydrogels. Hydrazone coupling of hydrophobic ligands to HA permits the encapsulation of simvastatin molecules in the resulting amphiphilic HA derivative and the subsequent acid-triggered release of the drug. The conjugation of BP and hydrophobic ligands to HA enables preparation of both bulk self-healing hydrogels and nanogels. Moreover, the developed hydrogel system is shown to be multi-responsive by applying orthogonally cleavable linkers. The presented hydrogel is a potential candidate for the combination treatment of osteoporosis and bone cancers as well as for bone tissue regeneration since it can deliver bone anabolic and anti-catabolic agents in response to bone diseases microenvironments.

Acid- and Thiol-Cleavable Multifunctional Codelivery Hydrogel: Fabrication and Investigation of Antimicrobial and Anticancer Properties

Hydrogels serving as a drug carrier was realized by entrapping small-sized drug molecules within their cross-linked interstitial networks. After covering the targeted location, hydrogels interact with the physiological fluids and swell, resulting in an increased interspace between networks for the outside diffusion of drugs. However, inevitable in vivo inflammatory responses or bacterial infection on the implant materials and persistent cargo release are still challenging. Herein, we report the fabrication of dual-responsive hydrogels based on acid-sensitive poly(ethylenimine) (PEI) derivative (PEI(-COOH/-vinyl)), thiol-responsive camptothecin prodrug monomer (CPTM), and hydrophilic oligo(ethylene glycol) methyl ether acrylate (OEGMA) by a conventional radical polymerization. Curcumin was then solubilized into the hydrogels to endow them with antimicrobial and cancer resistance properties. The in vitro experiments exhibited sustained hydrogel dissolution and CPT release in a simulated physiological environment. The antimicrobial and cytotoxicity tests of drug-loaded hydrogels using methicillin-resistant Staphylococcus aureus (MRSA) strains and HeLa cancer cell lines, respectively, indicated that the hydrogels possessed efficient antimicrobial effects and could successfully inhibit the growth of cancer cells.

In vitro and in vivo biocompatibility and inflammation response of methacrylated and maleated hyaluronic acid for wound healing

Over the past few years, different in vitro and in vivo studies have been highlighting the great potentiality of hyaluronic acid (HA) as a biomaterial in wound healing treatment thanks to its good capability to induce mesenchymal and epithelial cell growth and differentiation, angiogenesis, and collagen deposition. However, the need to improve its mechanical properties as well as its residence time has led scientists to study new functionalization strategies. In this work, chemically modified HA-based hydrogels were obtained by methacrylic and maleic functionalization. Methacrylated (MEHA) and maleated HA (MAHA) hydrogels have shown important physico-chemical properties. The present study provides a deeper insight into the biocompatibility of both synthesized materials and their effects on tissue inflammation using in vitro and in vivo models. To this aim, different cell lines involved in wound healing, human dermal fibroblasts, human adipose-derived stem cells and human umbilical vein endothelial cells, were seeded on MEHA and MAHA hydrogels. Furthermore, an inflammation study was carried out on a murine macrophage cell line to assess the effects of both hydrogels on inflammatory and anti-inflammatory interleukin production. The results showed that both MAHA and MEHA supported cell proliferation with anti-inflammation ability as highlighted by the increased levels of IL-10 (57.92 ± 9.87 pg mL⁻¹ and 68.08 ± 13.94 pg mL⁻¹, for MEHA and MAHA, respectively). To investigate the inflammatory response at tissue/implant interfaces, an in vivo study was also performed by subcutaneous implantation of the materials in BALB/c mice for up to 28 days. In these analyses, no significant chronic inflammation reaction was demonstrated in either MEHA or MAHA in the long-term implantation.

From synthesis to the in vitro and in vivo biological evaluation of two types of hyaluronan derivatives.

GSK3 inhibitor-loaded osteotropic Pluronic hydrogel effectively mitigates periodontal tissue damage associated with experimental periodontitis

Periodontitis is a chronic inflammatory disease caused by complex interactions between the host immune system and pathogens that affect the integrity of periodontium. To prevent disease progression and thus preserve alveolar bone structure, simultaneous anti-inflammatory and osteogenic intervention are essential. Hence, a glycogen synthase kinase 3 beta inhibitor (BIO) was selected as a potent inflammation modulator and osteogenic agent to achieve this treatment objective. BIO's lack of osteotropicity, poor water solubility, and potential long-term systemic side effects, however, have hampered its clinical applications. To address these limitations, pyrophosphorylated Pluronic F127 (F127-PPi) was synthesized and mixed with regular F127 to prepare an injectable and thermoresponsive hydrogel formulation (PF127) of BIO, which could adhere to hard tissue and gradually release BIO to exert its therapeutic effects locally. Comparing to F127 hydrogel, PF127 hydrogels exhibited stronger binding to hydroxyapatite (HA). Additionally, BIO's solubility in PF127 solution was dramatically improved over F127 solution and the improvement was proportional to the polymer concentration. When evaluated on a rat model of periodontitis, PF127-BIO hydrogel treatment was found to be very effective in preserving alveolar bone and ligament, and preventing periodontal inflammation, as shown by the micro-CT and histological data, respectively. Altogether, these findings suggested that the thermoresponsive PF127 hydrogel is an effective local drug delivery system for better clinical management of periodontitis and associated pathologies.

Nanomedicine Particles Associated With Chemical Exchange Saturation Transfer Contrast Agents in Biomedical Applications

Theranostic agents are particles containing both diagnostic and medicinal agents in a single platform. Theranostic approaches often employ nanomedicine because loading both imaging probes and medicinal drugs onto nanomedicine particles is relatively straightforward, which can simultaneously provide diagnostic and medicinal capabilities within a single agent. Such systems have recently been described as nanotheranostic. Currently, nanotheranostic particles incorporating medicinal drugs are being widely explored with multiple imaging methods, including computed tomography, positron emission tomography, single-photon emission computed tomography, magnetic resonance imaging, and fluorescence imaging. However, most of these particles are metal-based multifunctional nanotheranostic agents, which pose potential toxicity or radiation risks. Hence, alternative non-metallic and biocompatible nanotheranostic agents are urgently needed. Recently, nanotheranostic agents that combine medicinal drugs and chemical exchange saturated transfer (CEST) contrast agents have shown good promise because CEST imaging technology can utilize the frequency-selective radiofrequency pulse from exchangeable protons to indirectly image without requiring metals or radioactive agents. In this review, we mainly describe the fundamental principles of CEST imaging, features of nanomedicine particles, potential applications of nanotheranostic agents, and the opportunities and challenges associated with clinical transformations.

Prolonged Local In Vivo Delivery of Stimuli-Responsive Nanogels That Rapidly Release Doxorubicin in Triple-Negative Breast Cancer Cells

Triple negative breast cancer patients remain with chemotherapy as their only viable therapeutic option. However, the toxicity of available anticancer drugs and their inefficient delivery have limited the development of effective chemotherapy administration protocols and combination therapies. Drug delivery devices that can properly target chemotherapy to the right cells with efficient cancer-cell killing may play a vital role in eliminating triple-negative breast cancer. While systemic delivery results in low drug accumulation at the tumor site and for a short period of time, local delivery enables sustained drug release. However, a system that is able to provide rapid, yet prolonged action, would enable efficient tumor elimination. Herein, the development of dual-sensitive nanogels is described that are designed to rapidly dislodge the chemotherapy drug, doxorubicin, inside cancer cells through dual-sensitive action-pH and redox sensitivities-enabling efficient cancer-cell killing while eliminating systemic side effects. Their embedding within a hydrogel injected next to a tumor in a triple-negative breast-cancer mouse model enables prolonged release of the drug with instantaneous action when inside the cells resulting in efficacious tumor elimination compared to sustained local delivery only. This technology can be used for the delivery of combination therapies and for the treatment of other solid tumors.

Fabrication of novel MXene (Ti3C2)/polyacrylamide nanocomposite hydrogels with enhanced mechanical and drug release properties

A highly stretchable nanocomposite (NC) hydrogel was fabricated via in situ free radical polymerization of acrylamide. In particular, an exfoliated two-dimensional MXene (Ti₃C₂) nanosheet was utilized as a crosslinker instead of traditional organic crosslinkers. The exfoliated Ti₃C₂ nanosheets were confirmed by atomic force microscopy (AFM) and dynamic light scattering (DLS) measurements. Compared with traditional organic crosslinked N,N-methylene bisacrylamide (BIS)/polyacrylamide (PAM) hydrogels (fracture strength of 32.0 kPa and elongation of 109.6%), the synthesized Ti₃C₂/PAM NC hydrogels exhibited greatly improved mechanical properties with fracture strengths of 66.5 to 102.7 kPa, compressive strengths of 400.6 to 819.4 kPa and elongations at break of 2158.6% to 3047.5% as the Ti₃C₂ content increases from 0.0145% to 0.0436%. The enhanced mechanical performances can be attributed to the honeycomb-like fine structure with uniform pores as well as more flexible polymer chains in NC hydrogel networks. When loaded with drugs, Ti₃C₂/PAM NC hydrogels exhibited good sustained-release performance, higher drug loading amounts (97.5-127.7 mg g^-1) and higher percentage releases (62.1-81.4%), greatly superior to those of the BIS/PAM hydrogel (46.4 mg g^-1, 45.0%). Our work reveals the application of MXene materials in the fabrication of NC hydrogels with enhanced mechanical and drug release behaviors.

Inhalable nanotherapeutics to improve treatment efficacy for common lung diseases

Respiratory illnesses are prevalent around the world, and inhalation-based therapies provide an attractive, noninvasive means of directly delivering therapeutic agents to their site of action to improve treatment efficacy and limit adverse systemic side effects. Recent trends in medicine and nanoscience have prompted the development of inhalable nanomedicines to further enhance effectiveness, patient compliance, and quality of life for people suffering from lung cancer, chronic pulmonary diseases, and tuberculosis. Herein, we discuss recent advancements in the development of inhalable nanomaterial-based drug delivery systems and analyze several representative systems to illustrate their key design principles that can translate to improved therapeutic efficacy for prevalent respiratory diseases. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Respiratory Disease.

Chemical exchange saturation transfer magnetic resonance imaging and its main and potential applications in pre-clinical and clinical studies

Chemical exchange saturation transfer (CEST) imaging is a novel contrast mechanism, relying on the exchange between mobile protons in amide (-NH), amine (-NH2) and hydroxyl (-OH) groups and bulk water. Due to the targeted protons present in endogenous molecules or exogenous compounds applied externally, CEST imaging can respectively, generate endogenous or exogenous contrast. Nowadays, CEST imaging for endogenous contrast has been explored in pre-clinical and clinical studies. Amide CEST, also called amide proton transfer weighted (APT) imaging, generates CEST effect at 3.5 ppm away from the water signal and has been widely investigated. Given the sensitivity to amide proton concentration and pH level, APT imaging has shown robust performance in the assessment of ischemia, brain tumors, breast and prostate cancer as well as neurodegenerative diseases. With advanced methods proposed, pure APT and Nuclear Overhauser Effect (NOE) mediated CEST effects were separately fitted from original APT signal. Using both effects, early but promising results were obtained for glioma patients in the evaluation of tumor response to therapy and patient survival. Compared to amide CEST, amine CEST is also mobile proton concentration and pH dependent, but has a faster exchange rate between amine protons and water. The resultant CEST effect is usually introduced at 1.8-3 ppm. Glutamate and creatine, as two main metabolites with amine groups for CEST imaging, have been applied to quantitatively assess diseases in the central nervous system and muscle system, respectively. Glycosaminoglycan (Gag) as a representative metabolite with hydroxyl groups has also been measured to evaluate the cartilage of knee or intervertebral discs in CEST MRI. Due to limited frequency difference between hydroxyl protons and water, 7T for better spectral separation is preferred over 3T for GagCEST measurement. The applications of CEST MRI with exogenous contrast agents are still quite limited in clinic. While certain diamagnetic CEST agents, such as dynamic-glucose, have been tried in human for brain tumor or neck cancer assessment, most exogenous agents, i.e., paramagnetic CEST agents, are still tested in the pre-clinical stage, mainly due to potential toxicity. Engineered tissues for tissue regeneration and drug delivery have also shown a great potential in CEST imaging, as many of them, such as hydrogel and polyamide materials, contain mobile protons or can be incorporated with CEST specific chemical compounds. These engineered tissues can thus generate CEST effect in vivo, allowing a possibility to understand the fate of them in vivo longitudinally. Although the CEST MRI with engineered tissues has only been established in early stage, the obtained first evidence is crucial for further optimizing these biomaterials and finally accomplishing the translation into clinical use.

Oligo Hyaluronan-Coated Silica/Hydroxyapatite Degradable Nanoparticles for Targeted Cancer Treatment

Targeted drug delivery systems (TDDSs) provide a promising approach to overcome the side effect of traditional chemotherapy by specific tumor targeting and drug release. Hyaluronan (HA), as a selective CD44 targeting group, has been widely used in TDDSs for chemotherapy. However, different molecular weight HAs would demonstrate different binding ability to CD44, which may result in different therapeutic effects. Herein, a silica/hydroxyapatite (MSNs/HAP) hybrid carrier loaded with anticancer drug doxorubicin (DOX) (DOX@MSNs/HAP) is fabricated. HA and oligo HA (oHA) are coated onto the nanoparticles (HA-DOX@MSNs/HAP, oHA-DOX@MSNs/HAP), respectively, to investigate their performance in tumor targeting ability. oHA-DOX@MSNs/HAP shows much higher efficiency cellular uptake and drug release in tumor regions due to more effective CD44 targeting of oHA. Thus, the anticancer effect of oHA-DOX@MSNs/HAP is significantly enhanced compared to HA-DOX@MSNs/HAP, as demonstrated in a tumor-bearing mouse model. This study may enable the rational design of nanodrug systems for future tumor-targeted chemotherapy.

An Unexpected Role of Hyaluronic Acid in Trafficking siRNA Across the Cellular Barrier: The First Biomimetic, Anionic, Non-Viral Transfection Method

Circulating nucleic acids, such as short interfering RNA (siRNA), regulate many biological processes; however, the mechanism by which these molecules enter the cell is poorly understood. The role of extracellular-matrix-derived polymers in binding siRNAs and trafficking them across the plasma membrane is reported. Thermal melting, dynamic light scattering, scanning electron microscopy, and computational analysis indicate that hyaluronic acid can stabilize siRNA via hydrogen bonding and Van der Waals interactions. This stabilization facilitated HA size- and concentration-dependent gene silencing in a CD44-positive human osteosarcoma cell line (MG-63) and in human mesenchymal stromal cells (hMSCs). This native HA-based siRNA transfection represents the first report on an anionic, non-viral delivery method that resulted in approximately 60 % gene knockdown in both cell types tested, which correlated with a reduction in translation levels.

Hyaluronic acid modified MPEG-b-PAE block copolymer aqueous micelles for efficient ophthalmic drug delivery of hydrophobic genistein

The ophthalmic drug delivery is a challenge in the clinical treatment of ocular diseases. The traditional drug administration usually shows apparent limitations, such as the low bioavailability from the reason of low penetration of the cornea and the short survival time of drug in the eyes. To overcome these shortcomings, we propose an amphiphilic polymer micelle modified with hyaluronic acid (HA) for high efficient ophthalmic delivery of genistein, a widely used hydrophobic drug for treatment of ocular angiogenesis. The MPEG-b-PAE copolymer was synthesized by the Michael addition reaction, and the final drug carrier MPEG-b-PAE-g-HA was obtained by the process of esterification. Then, genistein was packaged in this drug carrier, getting the final micelles with size of about 84.5 nm. The cell viability tests showed that the micelles take no obvious cytotoxicity to the human cornea epithelium cells. The functionalities of drug slow release and cornea penetration ability were demonstrated in a series ex vivo experiments. Further, the vascular inhibition test illustrated that the micelles could significantly inhibit the angiogenesis of human umbilical vein endothelial cells. These results indicate that the constructed polymer has high feasibility to be used as drug carrier in the treatment of ocular diseases.

Bisphosphonate conjugation for bone specific drug targeting

Bones provide essential functions and are sites of unique biochemistry and specialized cells, but can also be sites of disease. The treatment of bone disorders and neoplasia has presented difficulties in the past, and improved delivery of drugs to bone remains an important goal for achieving effective treatments. Drug targeting strategies have improved drug localization to bone by taking advantage of the high mineral concentration unique to the bone hydroxyapatite matrix, as well as tissue-specific cell types. The bisphosphonate molecule class binds specifically to hydroxyapatite and inhibits osteoclast resorption of bone, providing direct treatment for degenerative bone disorders, and as emerging evidence suggests, cancer. These bone-binding molecules also provide the opportunity to deliver other drugs specifically to bone by bisphosphonate conjugation. Bisphosphonate bone-targeted therapies have been successful in treatment of osteoporosis, primary and metastatic neoplasms of the bone, and other bone disorders, as well as refining bone imaging. In this review, we focus upon the use of bisphosphonate conjugates with antineoplastic agents, and overview bisphosphonate based imaging agents, nanoparticles, and other drugs. We also discuss linker design potential and the current state of bisphosphonate conjugate research progress. Ongoing investigations continue to expand the possibilities for bone-targeted therapeutics and for extending their reach into clinical practice.

Chondroitin sulfate derived theranostic nanoparticles for targeted drug delivery

Glycosaminoglycan derived nanoparticles are a promising delivery system owing to their unique tumour targeting ability. Exploiting fluorescein for inducing amphiphilicity in these biopolymers provides inherent imaging and drug stabilization capabilities by π-π stacking interactions with aromatic antineoplastic agents. This offers a versatile and highly customizable nanocarrier with narrow size distribution and high drug loading efficiency (80%) with sustained drug release.

Hydrogel scaffolds for differentiation of adipose-derived stem cells

Natural extracellular matrices (ECMs) have been widely used as a support for the adhesion, migration, differentiation, and proliferation of adipose-derived stem cells (ADSCs). However, poor mechanical behavior and unpredictable biodegradation properties of natural ECMs considerably limit their potential for bioapplications and raise the need for different, synthetic scaffolds. Hydrogels are regarded as the most promising alternative materials as a consequence of their excellent swelling properties and their resemblance to soft tissues. A variety of strategies have been applied to create synthetic biomimetic hydrogels, and their biophysical and biochemical properties have been modulated to be suitable for cell differentiation. In this review, we first give an overview of common methods for hydrogel preparation with a focus on those strategies that provide potential advantages for ADSC encapsulation, before summarizing the physical properties of hydrogel scaffolds that can act as biological cues. Finally, the challenges in the preparation and application of hydrogels with ADSCs are explored and the perspectives are proposed for the next generation of scaffolds.

Self-assembled PEG–carboxymethylcellulose nanoparticles/α-cyclodextrin hydrogels for injectable and thermosensitive drug delivery

Novel cellulose hydrogels based on the inclusion complex between α-cyclodextrin and binary-drug loaded nanoparticles (carboxymethylcellulose–betulinic acid/hydroxycamptothecine nanoparticles) were prepared in aqueous media for the first time.

Bacterial Hyaluronidase Self-Triggered Prodrug Release for Chemo-Photothermal Synergistic Treatment of Bacterial Infection

A novel platform for targeted on-demand prodrug ascorbic acid (AA) delivery is fabricated using a bacterial hyaluronidase sensitive graphene-mesoporous silica nanosheet@hyaluronic acid-magnetic nanoparticles as the nanocarrier to treat bacterial infections. The released AA can be converted to detrimental •OH in situ on the surface of bacteria. With the chemo-photothermal synergistic effect, the designed antibacterial system can effectively inactivate bacteria and disperse stubborn biofilm.

A Synthetic Toolbox for the In Situ Formation of Functionalized Homo- and Heteropolysaccharide-Based Hydrogel Libraries

A synthetic toolbox for the introduction of aldehydo and hydrazido groups into the polysaccharides hyaluronic acid, alginate, dextran, pullulan, glycogen, and carboxymethyl cellulose and their use for hydrogel formation is reported. Upon mixing differently functionalized polysaccharides derived from the same natural precursor, hydrazone cross-linking takes place, which results in formation of a hydrogel composed of one type of polysaccharide backbone. Likewise, hydrogels based on two different polysaccharide strands can be formed after mixing the corresponding aldehydo- and hydrazido-modified polysaccharides. A second line of these studies paves the way to introduce a biomedically relevant ligand, namely, the adhesion factor cyclic RGD pentapeptide, by using an orthogonal click reaction. This set of modified polysaccharides served to create a library of hydrogels that differ in the combination of polysaccharide strands and the degree of cross-linking. The different hydrogels were evaluated with respect to their rheological properties, their ability to absorb water, and their cytotoxicity towards human fibroblast cell cultures. None of the hydrogels studied were cytotoxic, and, hence, they are in principal biocompatible for applications in tissue engineering.

Synthetic Procedures Leading towards Aminobisphosphonates

Growing interest in the biological activity of aminobisphosphonates has stimulated the development of methods for their synthesis. Although several general procedures were previously elaborated to reach this goal, aminobisphosphonate chemistry is still developing quite substantially. Thus, innovative modifications of the existing commonly used reactions, as well as development of new procedures, are presented in this review, concentrating on recent achievements. Additionally, selected examples of aminobisphosphonate derivatization illustrate their usefulness for obtaining new diagnostic and therapeutic agents.

Receptor-Meditated Endocytosis by Hyaluronic Acid@Superparamagnetic Nanovetor for Targeting of CD44-Overexpressing Tumor Cells

The present report proposes a more rational hyaluronic acid (HA) conjugation protocol that can be used to modify the surface of the superparamagnetic iron oxide nanoparticles (SPIONs) by covalently binding the targeting molecules (HA) with glutamic acid as a molecular linker on peripheral surface of SPIONs. The synthesis of HA-Glutamic Acid (GA)@SPIONs was included oxidization of nanoparticle’s surface with H₂O₂ followed by activation of hydroxyl group and reacting glutamic acid as an intermediate molecule demonstrating transfection of lung cancer cells. Fourier transform infrared (FTIR) and zeta-potential studies confirmed the chemical bonding between amino acid linker and polysaccharides. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay showed that HA-SPIONs-treated cells remained 82.9% ± 2.7% alive at high particle dosage (200 µg/mL iron concentration), whereas GA-SPIONs and bare SPIONs (B-SPIONs) treated cells had only 59.3% ± 13.4% and 26.5% ± 3.1% survival rate at the same conditions, respectively. Confocal microscopy analysis showed increased cellular internalization of HA-SPIONs compared to non-interacting agarose coated SPIONs (AgA-SPIONs).

Multifunctional Hyaluronic Acid and Chondroitin Sulfate Nanoparticles: Impact of Glycosaminoglycan Presentation on Receptor Mediated Cellular Uptake and Immune Activation

Hyaluronic acid (HA) and chondroitin sulfate (CS) polymers are extensively used for various biomedical applications, such as for tissue engineering, drug delivery, and gene delivery. Although both these biopolymers are known to target cell surface CD44 receptors, their relative cellular targeting properties and immune activation potential have never been evaluated. In this article, we present the synthesis and characterization of novel self-assembled supramolecular HA and CS nanoparticles (NPs). These NPs were developed using fluorescein as a hydrophobic component that induced amphiphilicity in biopolymers and also efficiently stabilized anticancer drug doxorubicin (DOX) promoting a near zero-order drug release. The cellular uptake and cytotoxicity studies of these NPs in different human cancer lines, namely, human colorectal carcinoma cell line HCT116 and human breast cancer cell line MCF-7 demonstrated dose dependent cytotoxicity. Interestingly, both NPs showed CD44 dependent cellular uptake with the CS-DOX NP displaying higher dose-dependent cytotoxicity than the HA-DOX NP in different mammalian cells tested. Immunological evaluation of these nanocarriers in an ex vivo human whole blood model revealed that unlike unmodified polymers, the HA NP and CS NP surprisingly showed platelet aggregation and thrombin-antithrombin complex formation at high concentrations (0.8 mg/mL). We also observed a clear difference in early- and late-stage complement activation (C3a and sC5b-9) with CS and CS NP triggering significant complement activation at high concentrations (0.08-0.8 mg/mL), unlike HA and HA NP. These results offer new insight into designing glycosaminoglycan-based NPs and understanding their hematological responses and targeting ability.

Hyaluronic acid-fibrin interpenetrating double network hydrogel prepared in situ by orthogonal disulfide cross-linking reaction for biomedical applications

To strengthen the mechanical properties of a fibrin gel and improve its applicability as a scaffold for tissue engineering (TE) applications, a strategy for the in situ preparation of the interpenetrating network (IPN) of fibrin and hyaluronic acid (HA) was developed on the basis of simultaneous and orthogonal fibrinogenesis and disulfide cross-linking. The synthetic pathway included the preparation of mutually reactive HA derivatives bearing thiol and 2-dithiopyridyl groups. Combining thiol-derivatized HA with thrombin and 2-dithiopyridyl-modified HA with fibrinogen and then mixing the obtained liquid formulations afforded IPNs with fibrin-resembling fibrillar architectures at different ratios between fibrin and HA networks. The formation of two networks was confirmed by conducting reference experiments with the compositions lacking one of the four components. The composition of 2% (w/v) fibrin and 1% (w/v) HA showed the highest storage modulus (G'), as compared with the single network counterparts. The degradation of fibrin in IPN hydrogels was slower than that in pure fibrin gels both during incubation of the hydrogels in a fibrin-cleaving nattokinase solution and during the culturing of cells after their encapsulation in the hydrogels. Together with the persistence of HA network, it permitted longer cell culturing time in the IPN. Moreover, the proliferation and spreading of MG63 cells that express the hyaluronan receptor CD44 in IPN hydrogel was increased, as compared with its single network analogues. These results are promising for tunable ECM-based materials for TE and regenerative medicine.

STATEMENT OF SIGNIFICANCE

The present work is devoted to in situ fabrication of injectable extracellular matrix hydrogels through simultaneous generation of networks of fibrin and hyaluronic acid (HA) that interpenetrate each other. This is accomplished by combination of enzymatic fibrin cross-linking with orthogonal disulphide cross-linking of HA. High hydrophilicity of HA prevents compaction of the fibrin network, while fibrin provides an adhesive environment for in situ encapsulated cells. The interpenetrating network hydrogel shows an increased stiffness along with a lower degradation rate of fibrin in comparison to the single fibrin network. As a result, the cells have sufficient time for the remodelling of the scaffold. This new approach can be applied for modular construction of in vitro tissue models and tissue engineering scaffolds in vivo.

Chondroitin sulfate coated gold nanoparticles: a new strategy to resolve multidrug resistance and thromboinflammation

We have developed the first chondroitin sulfate polymer coated gold nanoparticles that can simultaneously overcome mulidrug resistance in cancer cells and suppress thromboinflammation triggered by the chemotherapeutic drug.

Hyaluronic acid for anticancer drug and nucleic acid delivery

Hyaluronic acid (HA) is widely used in anticancer drug delivery, since it is biocompatible, biodegradable, non-toxic, and non-immunogenic; moreover, HA receptors are overexpressed on many tumor cells. Exploiting this ligand-receptor interaction, the use of HA is now a rapidly-growing platform for targeting CD44-overexpressing cells, to improve anticancer therapies. The rationale underlying approaches, chemical strategies, and recent advances in the use of HA to design drug carriers for delivering anticancer agents, are reviewed. Comprehensive descriptions are given of HA-based drug conjugates, particulate carriers (micelles, liposomes, nanoparticles, microparticles), inorganic nanostructures, and hydrogels, with particular emphasis on reports of preclinical/clinical results.

Response to di-functionalized hyaluronic acid with orthogonal chemistry grafting at independent modification sites in rodent models of neural differentiation and spinal cord injury

Hyaluronic acid functionalized with two orthogonal chemistries at different targets expedites neural maturation in vitro, while reducing inflammation in vivo.

Injectable Interpenetrating Network Hydrogels via Kinetically Orthogonal Reactive Mixing of Functionalized Polymeric Precursors

The enhanced mechanics, unique chemistries, and potential for domain formation in interpenetrating network (IPN) hydrogels have attracted significant interest in the context of biomedical applications. However, conventional IPNs are not directly injectable in a biological context, limiting their potential utility in such applications. Herein, we report a fully injectable and thermoresponsive interpenetrating polymer network formed by simultaneous reactive mixing of hydrazone cross-linked poly(N-isopropylacrylamide) (PNIPAM), and thiosuccinimide cross-linked poly(N-vinylpyrrolidone) (PVP). The resulting IPN gels rapidly (<1 min) after injection without the need for heat, UV irradiation, or small-molecule cross-linkers. The IPNs, cross-linked by kinetically orthogonal mechanisms, showed a significant synergistic enhancement in shear storage modulus compared to the individual component networks as well as distinctive pore morphology, degradation kinetics, and thermal swelling; in particular, significantly lower hysteresis was observed over the thermal phase transition relative to single-network PNIPAM hydrogels.

A Drosera-bioinspired hydrogel for catching and killing cancer cells

A variety of bioinspired materials have been successfully synthesized to mimic the sophisticated structures or functions of biological systems. However, it is still challenging to develop materials with multiple functions that can be performed synergistically or sequentially. The purpose of this work was to demonstrate a novel bioinspired hydrogel that can interact with cancer cells, functionally similar to Drosera in catching and killing prey. This hydrogel had two layers with the top one functionalized with oligonucleotide aptamers and the bottom one functionalized with double-stranded DNA. The results show that the top hydrogel layer was able to catch target cells with high efficiency and specificity, and that the bottom hydrogel layer could sequester doxorubicin (Dox) for sustained drug release. Importantly, the released Dox could kill 90% of the cells after 1-h residence of the cells on the hydrogel. After the cell release, this bifunctional hydrogel could be regenerated for continuous cell catching and killing. Therefore, the data presented in this study has successfully demonstrated the potential of developing a material system with the functions of attracting, catching and killing diseased cells (e.g., circulating tumor cells) or even invading microorganisms (e.g., bacteria).

Utilization of Glycosaminoglycans/Proteoglycans as Carriers for Targeted Therapy Delivery

The outcome of patients with cancer has improved significantly in the past decade with the incorporation of drugs targeting cell surface adhesive receptors, receptor tyrosine kinases, and modulation of several molecules of extracellular matrices (ECMs), the complex composite of collagens, glycoproteins, proteoglycans, and glycosaminoglycans that dictates tissue architecture. Cancer tissue invasive processes progress by various oncogenic strategies, including interfering with ECM molecules and their interactions with invasive cells. In this review, we describe how the ECM components, proteoglycans and glycosaminoglycans, influence tumor cell signaling. In particular this review describes how the glycosaminoglycan hyaluronan (HA) and its major receptor CD44 impact invasive behavior of tumor cells, and provides useful insight when designing new therapeutic strategies in the treatment of cancer.

Imine Hydrogels with Tunable Degradability for Tissue Engineering

A shortage of available organ donors has created a need for engineered tissues. In this context, polymer-based hydrogels that break down inside the body are often used as constructs for growth factors and cells. Herein, we report imine cross-linked gels where degradation is controllable by the introduction of mixed imine cross-links. Specifically, hydrazide-functionalized poly(ethylene glycol) (PEG) reacts with aldehyde-functionalized PEG (PEG-CHO) to form hydrazone linked hydrogels that degrade quickly in media. The time to degradation can be controlled by changing the structure of the hydrazide group or by introducing hydroxylamines to form nonreversible oxime linkages. Hydrogels containing adipohydrazide-functionalized PEG (PEG-ADH) and PEG-CHO were found to degrade more rapidly than gels formed from carbodihydrazide-functionalized PEG (PEG-CDH). Incorporating oxime linkages via aminooxy-functionalized PEG (PEG-AO) into the hydrazone cross-linked gels further stabilized the hydrogels. This imine cross-linking approach should be useful for modulating the degradation characteristics of 3D cell culture supports for controlled cell release.