Synthesis by gamma irradiation of hyaluronic acid-polyvinyl alcohol hydrogel for biomedical applications.

Hyaluronic acid (HA) is one of the most attractive natural polymers employed in biomaterials with biological applications. This polysaccharide is found in different tissues of the body because it is a natural component of the extracellular matrix; furthermore, it has crucial functions in cell growth, migration, and differentiation. Since its biological characteristics, HA has been utilized for the new biomaterial's development for tissue engineering, such as hydrogels. These hydrophilic macromolecular networks have gained significant attention due to their unique properties, making them potential candidates to be applied in biomedical fields. Different mechanisms to obtain hydrogels have been described. However, the research of new non-toxic methods has been growing in recent years. In this study, we prepared a new hydrogel of HA and polyvinyl alcohol by the cost-effective technique of cross-linking by gamma irradiation. The hydrogel was elaborated for the first time and was characterized by several methods such as Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry, Thermogravimetric Analysis, and Scanning Electron Microscopy. Likewise, we evaluated the cytotoxicity of the biomaterial and its influence on cell migration in human fibroblasts. Furthermore, we provide preliminary evidence of the wound closure effect in a cellular wound model. The novel hydrogel offers an increase of HA stability with the potential to expand the useful life of HA in its different medical applications.

Polyplexes of retinoic acid: an in vitro study of complex nanostructures against colorectal cancer cell line (HCT-15).

Despite recent advances in the treatment of human colon cancer, the chemotherapeutic efficacy against colon cancer is still unsatisfactory. The complexity in colorectal cancer treatment leads to new research in combination therapy to overcome multidrug resistance in cancer and increase apoptosis. The objective of the present research work was to develop polyplexes for co-delivery of plasmid DNA with retinoic acid against colorectal cancer cell line (HCT-15). Plain polyplexes were prepared using chitosan and hyaluronic acid solution (0.1% w/v), whereas retinoic acid polyplexes were prepared using ethanol: water (1:9 v/v) system. The particle size was observed in the order of chitosan solution > blank polyplex > retinoic acid-loaded polyplex. Encapsulation efficiency of retinoic acid was found to be 81.51 ± 4.33% for retinoic acid-loaded polyplex formulation. The drug release was observed to be in a controlled pattern with 72.23 ± 1.32% release of retenoic acid from polyplex formulation. Cell line studies of the formulation displayed better cell inhibition and low cytotoxicity for the retinoic acid-loaded polyplexes in comparison to pure retinoic acid, thus demonstrating better potential action against colorectal cancer cell line HCT-15. Retinoic acid-loaded polyplexes indicated higher potential for the delivery of the active whereas the cell line studies displayed the efficacy of the formulation against colorectal cancer cell line HCT-15.

Evaluation of hyaluronic acid nanoparticle embedded chitosan-gelatin hydrogels for antibiotic release.

The development of chitosan-gelatin (CS-G) hydrogels embedded with ampicillin-loaded hyaluronic acid nanoparticles (HA-NPs) for wound dressing is proposed. It was aimed to provide controlled ampicillin delivery by incorporation of HA-NPs into biocompatible CS-G hydrogel structure. According to in vitro ampicillin release studies, 55% of ampicillin was released from CS-G/HA-NPs hydrogels after 5 days. Antibacterial performance of CS-G/HA-NPs hydrogels was proven with agar disc diffusion test. For cytotoxicity assay, fibroblast cell viability increased in CS-G/HA-NPs hydrogels compared with CS-G group after 24 hr incubation. Consequently, the potential ability of CS-G/HA-NPs hydrogels as a controlled drug delivery system has been verified.

A Novel Carbon Dots/Thermo-Sensitive In Situ Gel for a Composite Ocular Drug Delivery System: Characterization, Ex-Vivo Imaging, and In Vivo Evaluation.

We developed a potential composite ocular drug delivery system for the topical administration of diclofenac sodium (DS). The novel carbon dot CDC-HP was synthesized by the pyrolysis of hyaluronic acid and carboxymethyl chitosan through a one-step hydrothermal method and then embedded in a thermosensitive in situ gel of poloxamer 407 and poloxamer 188 through swelling loading. The physicochemical characteristics of these carbon dots were investigated. The results of the in vitro release test showed that this composite ocular drug delivery system (DS-CDC-HP-Gel) exhibited sustained release for 12 h. The study of the ex vivo fluorescence distribution in ocular tissues showed that it could be used for bioimaging and tracing in ocular tissues and prolong precorneal retention. Elimination profiles in tears corresponded to the study of ex vivo fluorescence imaging. The area under the curve of DS in the aqueous humor in the DS-CDC-HP-Gel group was 3.45-fold that in the DS eye drops group, indicating a longer precorneal retention time. DS-CDC-HP with a positive charge and combined with a thermosensitive in situ gel might strengthen adherence to the corneal surface and prolong the ocular surface retention time to improve the bioavailability. This composite ocular delivery system possesses potential applications in ocular imaging and drug delivery.

Synthetic Studies on the Incorporation of N-Acetylallosamine in Hyaluronic Acid-Inspired Thiodisaccharides.

Two approaches for the synthesis of the thiodisaccharide ß-S-GlcA(1→3)ß-S-AllNAc are described here. The target disaccharide was a C-3 epimer and thio-analogue of the hyaluronic acid repetitive unit, tuned with a thiopropargyl anomeric group for further click conjugation. Thus, we analysed and tested two convenient sequences, combining the two key steps required to introduce the thioglycosidic bonds and consequently reach the target molecule: the SN2 substitution of a good leaving group (triflate) present at C-3 of a GlcNAc derivative and the introduction of the anomeric thiopropargyl substituent. The use of a 2-azido precursor showed to be a convenient substrate for the SN2 step. Nevertheless, further protecting group manipulation and the introduction of the thiopropargyl anomeric residue were then required. This approach showed to provide access to a variety of thiodisaccharide derivatives as interesting building blocks for the construction of neoglycoconjugates.

Hyaluronic Acid Derivative Effect on Niosomal Coating and Interaction with Cellular Mimetic Membranes.

Hyaluronic acid (HA) is one of the most used biopolymers in the development of drug delivery systems, due to its biocompatibility, biodegradability, non-immunogenicity and intrinsic-targeting properties. HA specifically binds to CD44; this property combined to the EPR effect could provide an option for reinforced active tumor targeting by nanocarriers, improving drug uptake by the cancer cells via the HA-CD44 receptor-mediated endocytosis pathway. Moreover, HA can be easily chemically modified to tailor its physico-chemical properties in view of specific applications. The derivatization with cholesterol confers to HA an amphiphilic character, and then the ability of anchoring to niosomes. HA-Chol was then used to coat Span® or Tween® niosomes providing them with an intrinsic targeting shell. The nanocarrier physico-chemical properties were analyzed in terms of hydrodynamic diameter, ζ-potential, and bilayer structural features to evaluate the difference between naked and HA-coated niosomes. Niosomes stability was evaluated over time and in bovine serum. Moreover, interaction properties of HA-coated nanovesicles with model membranes, namely liposomes, were studied, to obtain insights on their interaction behavior with biological membranes in future experiments. The obtained coated systems showed good chemical physical features and represent a good opportunity to carry out active targeting strategies.

Synthesis of hyaluronic acid oligosaccharides with a GlcNAc-GlcA repeating pattern and their binding affinity with CD44.

Hyaluronic acid (HA) is a ubiquitous glycosaminoglycan in the extracellular matrix and a ligand of CD44, a transmembrane glycoprotein that is important in cell migration. Crystal and NMR studies found a hexasaccharide of the pattern (GlcA-GlcNAc)3 as the shortest HA that could bind to CD44, but molecular dynamics simulations indicated that a tetrasaccharide of the pattern (GlcNAc-GlcA)2 is the key structure interacting with CD44. Access to oligomers with such a repeat pattern is crucial in binding studies with CD44. Here we developed a synthetic procedure to afford the HA oligosaccharides with the GlcNAc-GlcA repeating unit and measured the binding interaction between these sugars and human CD44 by isothermal titration calorimetry (ITC). During the chemical synthesis, we successfully generated the ß-glycosidic bond in the absence of neighbouring group participation and overcome the issues in the oxidation step. In addition, ammonia-free dissolving metal reduction for debenzylation and azido reduction has been applied in carbohydrate synthesis for the first time. ITC analysis revealed that the HA tetrasaccharide (GlcNAc-GlcA)2 could indeed interact and bind to the human CD44.

Tumor- and mitochondria-targeted nanoparticles eradicate drug resistant lung cancer through mitochondrial pathway of apoptosis.

Chemotherapeutic drugs frequently encounter multidrug resistance. ATP from mitochondria helps overexpression of drug efflux pumps to induce multidrug resistance, so mitochondrial delivery as a means of "repurposing'' chemotherapeutic drugs currently used in the clinic appears to be a worthwhile strategy to pursue for the development of new anti-drug-resistant cancer agents. TPP-Pluronic F127-hyaluronic acid (HA) (TPH), with a mitochondria-targeting triphenylphosphine (TPP) head group, was first synthesized through ester bond formation. Paclitaxel (PTX)-loaded TPH (TPH/PTX) nanomicelles exhibited excellent physical properties and significantly inhibited A549/ADR cells. After TPH/PTX nanomicelles entered acidic lysosomes through macropinocytosis, the positively charged TP/PTX nanomicelles that resulted from degradation of HA by hyaluronidase (HAase) in acidic lysosomes were exposed and completed lysosomal escape at 12 h, finally localizing to mitochondria over a period of 24 h in A549/ADR cells. Subsequently, TPH/PTX caused mitochondrial outer membrane permeabilization (MOMP) by inhibiting antiapoptotic Bcl-2, leading to cytochrome C release and activation of caspase-3 and caspase-9. In an A549/ADR xenograft tumor model and a drug-resistant breast cancer-bearing mouse model with lung metastasis, TPH/PTX nanomicelles exhibited obvious tumor targeting and significant antitumor efficacy. This work presents the potential of a single, nontoxic nanoparticle (NP) platform for mitochondria-targeted delivery of therapeutics for diverse drug-resistant cancers.

Lipid/Hyaluronic Acid-Coated Doxorubicin-Fe3O4 as a Dual-Targeting Nanoparticle for Enhanced Cancer Therapy.

Development of a delivery system to lower systemic toxicity and enhance doxorubicin (DOX) antitumor efficacy against multi-drug resistant (MDR) tumors is of great clinical significance. Here, lipid/hyaluronic acid (HA)-coated DOX-Fe3O4 was characterized to determine its optimal safety and efficacy on a tumor. DOX was first conjugated onto the Fe3O4 NPs surface, which was subsequently coated with phosphatidylcholine (PC) lipids, which consisted of a tumor cell-targeting HA ligand, to generate a dual-targeting nanoparticle (NP). DOX-Fe3O4 synthesis was validated by the Fourier-transform infrared (FT-IR) analysis results. Core-shell PC/HA@DOX-Fe3O4 formation, which had an average particle size of 48.2 nm, was observed based on the transmission electron microscopy (TEM) and dynamic laser light scattering (DLS) results. The saturation magnetization value of PC/HA@DOX-Fe3O4 was discovered to be 28 emu/g using vibrating-sample magnetometry. Furthermore, the designed PC/HA@DOX-Fe3O4 achieved greater MCF-7/ADR cellular uptake and cytotoxicity as compared with DOX. In addition, PC/HA@DOX-Fe3O4 exhibited significant DOX tumor-targeting capabilities and enhanced tumor growth inhibition activity in the xenograft MCF-7/ADR tumor-bearing nude mice following magnetic attraction and ligand-mediated targeting, with less cardiotoxicity. Therefore, PC/HA@DOX-Fe3O4 is a potential candidate for MDR tumor chemotherapy. Graphical abstract.

Thermosensitive hybrid hyaluronan/p(HPMAm-lac)-PEG hydrogels enhance cartilage regeneration in a mouse model of osteoarthritis.

Osteoarthritis (OA), due to cartilage degeneration, is one of the leading causes of disability worldwide. Currently, there are not efficacious therapies to reverse cartilage degeneration. In this study we evaluated the potential of hybrid hydrogels, composed of a biodegradable and thermosensitive triblock copolymer cross-linked via Michael addition to thiolated hyaluronic acid, in contrasting inflammatory processes underlying OA. Hydrogels composed of different w/w % concentrations of hyaluronan were investigated for their degradation behavior and capacity to release the polysaccharide in a sustained fashion. It was found that hyaluronic acid was controllably released during network degradation with a zero-order release kinetics, and the release rate depended on cross-link density and degradation kinetics of the hydrogels. When locally administered in vivo in an OA mouse model, the hydrogels demonstrated the ability to restore, to some extent, bone remineralization, proteoglycan production, levels of Sox-9 and Runx-2. Furthermore, the downregulation of proinflammatory mediators, such as TNF-α, NFkB, and RANKL and proinflammatory cytokines was observed. In summary, the investigated hydrogel technology represents an ideal candidate for the potential encapsulation and release of drugs relevant in the field of OA. In this context, the hydrogel matrix could act in synergy with the drug, in reversing phenomena of inflammation, cartilage disruption, and bone demineralization associated with OA.

Differentiation of Intracellular Hyaluronidase Isoform by Degradable Nanoassembly Coupled with RNA-Binding Fluorescence Amplification.

Hyaluronidase has two cruical isoforms, hyaluronidase-1 (Hyal-1) and hyaluronidase-2 (Hyal-2), which are essential for cellular hyaluronic acid (HA) catabolism to generate different-sized oligosaccharide fragments for performing different physiological functions. In particular, Hyal-1 is the major tumor-derived hyaluronidase. Thus, specific detection of one hyaluronidase isoform, especially Hyal-1, in live cells is of scientific significance but remains challenging. Herein, by use of differentiated tolerance capability of an amphiphilic HA-based nanoassembly to Hyal-1 and Hyal-2, we rationally design a Hyal-1 specific nanosensor, consisting of cholesterylamine-modified HA nanoassembly (CHA) and RNA-binding fluorophores (RBF). The RBF molecules were entrapped in CHA to switch off their fluorescence via aggregation caused quenching. However, CHA can be disassembled by Hyal-1 to release RBF, resulting in fluorescence activation. Moreover, the fluorescence of the released RBF is further enhanced by cytoplasm RNA. Owing to this cascade signal amplification, this nanosensor RBF@CHA displays a significant change of signal-to-background-noise ratio (120-fold) toward 16 µg/mL Hyal-1 in cellular lysates. In contrast, it is resistant to Hyal-2. By virtue of its selective and sensitive characteristics under a complicated matrix, RBF@CHA had been successfully applied for specifically visualizing Hyal-1 over Hyal-2 inside live cells for the first time, detecting a low level of intracellular Hyal-1 and distinguishing normal and cancer cells with different expressions of Hyal-1. This approach would be useful to better understand biological functions and related diseases of intracellular Hyal-1.

Bioinspired Hyaluronic Acid/Phosphorylcholine Polymer with Enhanced Lubrication and Anti-Inflammation.

Under pathological conditions, the joint is not well lubricated, which inevitably leads to osteoarthritis. Currently, in clinics injection of hyaluronic acid (HA) as an intra-articular viscosupplement is one of the main methods for alleviation of osteoarthritis. However, the viscosity of HA reduces dramatically under high shear rate due to the shear-thinning effect. Therefore, it is crucial to enhance the lubrication property of HA in order to treat osteoarthritis effectively. In this study, we successfully grafted 2-methacryloyloxyethyl phosphorylcholine (MPC), which is a zwitterionic biomaterial with excellent hydration lubrication, onto the HA with two different molecular weights (HAMPC) to enhance lubrication. The lubrication test performed using an atomic force microscope showed that, compared with HA, the friction coefficient of HAMPC was greatly reduced under various conditions. The in vitro test demonstrated that HAMPC was biocompatible and could upregulate cartilage anabolic genes while simultaneously downregulating cartilage catabolic proteases and pain-related genes. Importantly, high molecular weight HAMPC exhibited improved the capability to regulate these genes compared with low molecular weight HAMPC. In conclusion, the high molecular weight HAMPC developed herein, with enhanced lubrication and anti-inflammation, may be a promising polymer for the treatment of osteoarthritis.

Dual-ligand functionalized carbon nanodots as green fluorescent nanosensors for cellular dual receptor-mediated targeted imaging.

The conjugation of ligands to nanoparticles as drug delivery systems that target specific cells is a promising approach for the delivery of therapeutic agents to tumor cells. Herein, we prepared green-emission fluorescent carbon nanodots (CNDs) by a facile hydrothermal method with d-(+)-glucosamine hydrochloride and l-aspartic acid as the precursors, then covalently conjugated with folate (FA), polyethyleneimine (PEI) and hyaluronic acid (HA) to develop dual ligand-decorated nanocarriers (FA-PEI-HA-CNDs) for the targeted imaging of cancer cells. FA-PEI-HA-CNDs integrated the excellent fluorescence property of CNDs, and can be used for the real-time and noninvasive location tracking of cancer cells. The cellular uptake study demonstrated that FA-PEI-HA-CNDs markedly improved the internalization efficiency in A-549 cells via folate/CD44 receptor-mediated endocytosis in comparison with that of the A549 cells pretreated with excess FA, HA, and FA and HA. Therefore, these dual folate/CD44 receptor-targeted CNDs (FA-PEI-HA-CNDs) show promising potential for cancer detection, drug delivery, and individualized treatment as performance platforms.

pH and redox dual responsive carrier-free anticancer drug nanoparticles for targeted delivery and synergistic therapy.

Advanced drug delivery systems often employ nanomaterials as carriers to deliver drugs to desirable disease sites for enhanced efficacy. However, most systems have low drug loading capacity and cause safety concerns. Therefore, many anticancer therapeutics have recently been assembled to NPs form without using any additional nanocarrier to achieve high drug loading. However, carrier-free nanomedicines are often constrained by limitations such as inadequate stability and lack of control in drug release. Therefore, we synthesize carrier-free drug NPs containing cis-aconitic anhydride-modified doxorubicin and paclitaxel (CAD-PTX) and coating with crosslinked (CL) surfactant based on hyaluronic acid (HA) segment. With this design, the pure drug NPs possess pH and redox dual responsive release characteristic and could target CD44 overexpressed cancer cells. Our studies demonstrate that these CAD-PTX-CLHA NPs display high stability, excellent active targeting effect and controllable intracellular drug release, and ultimately achieve significantly better anti-cancer efficiency than individual doxorubicin and paclitaxel.

Pea-like nanocabins enable autonomous cruise and step-by-step drug pushing for deep tumor inhibition.

Pea-like nanocabins (HA@APT§DOX) were designed for deep tumor inhibition. The AS1411 aptamer (APT) constituted "core shelf" which guaranteed DOX "beans" could be embedded, while the outer HA acted as "pea shell" coating. During the circulation (primary orbit), HA@APT§DOX could autonomously cruise until leak through tumor vasculature. Upon tumor superficial site, the "pea shell" could be degraded by highly expressed hyaluronic acid enzymes (HAase) and peel-off, resulting in orbit changing of released APT§DOX to reach the deep tumor tissue. Furthermore, APT§DOX could be specifically uptaken into A549 tumor cells (secondary orbit). Finally, DOX was released under the acidic environment of lysosome, and delivered into nuclear (targeting orbit) to achieve drug pushing for deep tumor inhibition. More importantly, the in vivo imaging and anti-tumor effects evaluations showed that these nanocabins could effectively enhance drugs accumulation in tumor sites and inhibit tumor growth, with reduced systemic toxicity in 4T1 tumor-bearing mice.

A New Hyaluronan Modified with ß-Cyclodextrin on Hydroxymethyl Groups Forms a Dynamic Supramolecular Network.

A new hyaluronan derivative modified with ß-cyclodextrin units (CD-HA) was prepared via the click reaction between propargylated hyaluronan and monoazido-cyclodextrin (CD) to achieve a degree of substitution of 4%. The modified hyaluronan was characterized by 1H-nuclear magnetic resonance spectroscopy (NMR) and size exclusion chromatography. Subsequent 1H-NMR and isothermal calorimetric titration experiments revealed that the CD units on CD-HA can form virtual 1:1, 1:2, and 1:3 complexes with one-, two-, and three-site adamantane-based guests, respectively. These results imply that the CD-HA chains used the multitopic guests to form a supramolecular cross-linked network. The free CD-HA polymer was readily restored by the addition of a competing macrocycle, which entrapped the cross-linking guests. Thus, we demonstrated that the new CD-HA polymer is a promising component for the construction of chemical stimuli-responsive supramolecular architectures.

Development and Assessment of Lipidic Nanoemulsions Containing Sodium Hyaluronate and Indomethacin.

The present work attempts to develop and optimize the formula of a lipidic nanoemulsion (NE) containing sodium hyaluronate (HNa) and indomethacin (Ind) as HNa-Ind for enhanced transdermal antiarthritic activity. NEs were prepared by the spontaneous emulsification method and characterized by Fourier-transform infrared (FTIR) spectroscopy. The composition of the optimal formulation was statistically optimized using Box-Behnken experimental design method with three independent factors and was characterized for particle size, polydispersity index, and percent transmittance. The selected formula was tested for its in vitro antioxidant activity and in vivo anti-inflammatory activity. The optimized HNa-Ind NE formula was characterized and displayed a particle size of 12.87 ± 0.032 nm, polydispersity index of 0.606 ± 0.082, and 99.4 ± 0.1 percentage of transmittance. FTIR showed no interaction between HNa and Ind as a physical mixture. In addition, the optimized HNa-Ind NE was able to preserve the antioxidant ability of the two drugs, as evidenced through a 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition assay used to assess free radical scavenging ability. The cell viability was increased while the free radical scavenging activity was decreased (94.28% inhibition at higher concentrations compared with vitamin C as a reference with an inhibition of 100%). Moreover, the pharmacological anti-inflammatory potential of the optimized HNa-Ind NE formulation was assessed using an in vivo model. Compared with reference drugs (ibuprofen gel 5%), the remarkable activity of the optimized formulation was established using xylene-induced ear edema in mice model, in which the inflamed region reduced by 92.5% upon treatment. The optimized HNa-Ind NE formulation showed considerably higher skin permeation and drug deposition capability compared with the HNa-Ind solution. HNa-Ind NE was demonstrated to be a successful carrier with enhanced antioxidant and anti-inflammatory potential while showing better skin penetration, thus being a promising vehicle for transdermal drug delivery.

Preparation, Optimization, and Evaluation of Hyaluronic Acid-Based Hydrogel Loaded with Miconazole Self-Nanoemulsion for the Treatment of Oral Thrush.

Miconazole nitrate (MZ) is a BCS class II antifungal poorly water-soluble drug with limited dissolution properties and gastrointestinal side effects. Self-nanoemulsifying delivery system-based gel of MZ can improve both solubility and oral mucosal absorption with enhanced antifungal activity. The study aims to formulate MZ self-nanoemulsion (MZ-NE) and combine it within hyaluronic acid-based gel. MZ solubility in various oils, surfactants, and cosurfactant used in NE formulations were evaluated. Mixture design was implemented to optimize the levels of NE components as a formulation variable to study their effects on the mean globule size and antifungal inhibition zones. Further, the optimized MZ-NE was loaded into a hyaluronic acid gel base. Rheological behavior of the prepared gel was assessed. Ex vivo permeability of optimized formulation across buccal mucous of sheep and inhibition against Candida albicans were examined. Mixture design was used to optimize the composition of MZ-NE formulation as 22, 67, and 10% for clove oil, Labrasol, and propylene glycol, respectively. The optimized formulation indicated globule size of 113 nm with 29 mm inhibition zone. Pseudoplastic flow with thixotropic behavior was observed, which is desirable for oral gels. The optimized formulation exhibited higher ex vivo skin permeability and enhanced antifungal activity by 1.85 and 2.179, respectively, compared to MZ-SNEDDS, and by 1.52 and 1.72 folds, respectively, compared to marketed gel. Optimized MZ-NE hyaluronic acid-based oral gel demonstrated better antifungal activity, indicating its potential in oral thrush pharmacotherapy.

PD-1 Blockade for Improving the Antitumor Efficiency of Polymer-Doxorubicin Nanoprodrug.

Chemotherapy is well recognized to induce immune responses during some chemotherapeutic drugs-mediated tumor eradication. Here, a strategy involving blocking programmed cell death protein 1 (PD-1) to enhance the chemotherapeutic effect of a doxorubicin nanoprodrug HA-Psi-DOX is proposed and the synergetic mechanism between them is further studied. The nanoprodrugs are fabricated by conjugating doxorubicin (DOX) to an anionic polymer hyaluronic acid (HA) via a tumor overexpressed matrix metalloproteinase sensitive peptide (CPLGLAGG) for tumor targeting and enzyme-activated drug release. Once accumulated at the tumor site, the nanoprodrug can be activated to release antitumor drug by tumor overexpressed MMP-2. It is found that HA-Psi-DOX nanoparticles can kill tumor cells effectively and initiate an antitumor immune response, leading to the upregulation of interferon-γ. This cytokine promotes the expression of programmed cell death protein-ligand 1 (PD-L1) on tumor cells, which will cause immunosuppression after interacting with PD-1 on the surface of lymphocytes. The results suggest that the therapeutic efficiency of HA-Psi-DOX nanoparticles is significantly improved when combined with checkpoint inhibitors anti-PD-1 antibody (α-PD1) due to the neutralization of immunosuppression by blocking the interaction between PD-L1 and PD-1. This therapeutic system by combining chemotherapy and immunotherapy further increases the link between conventional tumor therapies and immunotherapy.

Enzymatic degradation of hyaluronan hydrogels with different capacity for in situ bio-mineralization.

In situ cross-linked hyaluronan (HA) hydrogels with different capacities for biomineralization were prepared and their enzymatic degradation was monitored. Covalent incorporation of bisphosphonates (BPs) into HA hydrogel results in the increased stiffness of the hydrogel in comparison with the unmodified HA hydrogel of the same cross-linking density. The rate of enzymatic degradation of HABP hydrogel was significantly lower than the rate of degradation of control HA hydrogel in vitro. This effect is observed only in the presence of calcium ions that strongly bind to the matrix-anchored BP groups and promote further mineralization of the matrix. The degradation of the hydrogels was followed by noninvasive fluorescence measurements enabled after mild and chemoselective labeling of cross-linkable HA derivatives with a fluorescent tag.