Chemical functionalization of hyaluronic acid for drug delivery applications

Hyaluronate-functionalized hydroxyapatite nanoparticles laden with methotrexate and teriflunomide for the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA), an autoimmune inflammatory disorder is currently incurable. Methotrexate and Teriflunomide are routinely prescribed drugs but their uses are limited due to severe hepatotoxicity. Hyaluronic acid (HYA) is a targeting ligand for CD44 receptors overexpressed on inflamed macrophages. The present investigation aimed at design and fabrication of HYA coated hydroxyapatite nanoparticles (HA-NPs) loaded with Methotrexate (MTX) and Teriflunomide (TEF) (HAMT-NPs) to form HYA-HAMT-NPs for the treatment of RA. HYA-HAMT-NPs showed the nanoscale size of 274.9 ± 64 nm along with a zeta potential value of -26.80 ± 6.08 mV. FTIR spectra of HYA and HYA-HAMT-NPs proved the coating of HYA on HYA-HAMT-NPs. HYA-HAMT-NPs showed less cell viability compared to drugs on RAW 264.7 macrophage cells. A biodistribution study by gamma scintigraphy imaging further strengthened the results by revealing significantly higher (p<0.05) percentage radioactivity (76.76%) of HYA-HAMT-NPs in the synovial region. The results obtained by pharmacodynamic studies ensured the better efficacy of HYA-HAMT-NPs in preventing disease progression and promoting articular regeneration. Under hepatotoxicity evaluation, liver histopathology and liver enzyme assay revealed ~29% hepatotoxicity was reduced by HYA-HAMT-NPs when compared to conventional FOLITRAX-10 and AUBAGIO oral treatments. Overall, the results suggest that HYA-HAMT-NP is a promising delivery system to avoid drug-induced hepatotoxicity in RA.

Miscibility Studies of Hyaluronic Acid and Poly(Vinyl Alcohol) Blends in Various Solvents

In this study, blends based on hyaluronic acid (HA) and poly(vinyl alcohol) (PVA) were characterized by the viscometric method, steady shear rheological tests and FTIR spectroscopy (Fourier Transform Infrared Spectroscopy). Viscometric studies showed the miscibility of HA and PVA in distilled water: 0.1 mol dm-3 NaCl and 0.1 mol dm-3 HCl. The method proposed by Garcia et al. was applied to assess the miscibility of polymers, while Δ[η] and Δb were introduced to determine of miscibility from the Huggins plots. The viscometric data showed that the attractive forces of HA and PVA were dominant when dissolved in 0.1 mol dm-3 NaCl and 0.1 mol dm-3 HCl, while, in distilled water, repulsive forces played the leading role. All polymer solutions were well characterized using a power law model, and exhibited non-Newtonian behavior with pseudoplasticity increasing with the increasing weight fraction of HA in 0.1 mol dm-3 NaCl and 0.1 mol dm-3 HCl. FTIR studies exhibited the formation of new intermolecular interactions between HA and PVA via hydrogen bonding.

Improving physical and biological properties of nylon monofilament as suture by Chitosan/Hyaluronic acid

One way to give some properties such as antibacterial and good frictional properties to sutures is the application of natural antibacterial and hydrophilic components on their surfaces through layer by layer assembly (LBL) technique. In this regard, Chitosan as an antibacterial polycationic natural polymer along with Hyaluronic acid (HA) as a polyanionic polysaccharide could be used to form a polyelectrolyte complex. In this study, HA was extracted from rooster comb using different solvents. Characterization of the extracted HA by FTIR and GPC analysis showed extracted HA with M_w = 2.53 × 10⁵ Da had no cytotoxicity. Then, a nylon monofilament (NMy) was coated by the extracted HA and chitosan with different concentrations using bilayer coating technique. Two dyes also were loaded to coating layer to investigate the release behavior of these two drug models. The morphology of coated layer showed that coating NMy by chitosan (4% w/v) following by HA (8% w/v) with roughness of 164 ± 129 nm and friction coefficient of 0.26 had suitable interaction between two layers to prevent from exfoliation of coating layers. The antibacterial activity and controlled release of coated NMy indicated how a NMy coated by Chitosan and HA is a promising material for using as a suture.

Identification of Biomarker Hyaluronan on Colon Cancer Extracellular Vesicles Using Correlative AFM and Spectroscopy

Extracellular vesicles (EVs), naturally occurring nanosized vesicles secreted from cells, are essential for intercellular communication. They carry unique biomolecules on the surface or interior that are of great interest as biomarkers for various pathological conditions such as cancer. In this work, we use high-resolution atomic force microscopy (AFM) and spectroscopy (AFS) techniques to demonstrate differences between EVs derived from colon cancer cells and colon epithelial cells at the single-vesicle level. We observe that EV populations are significantly increased in the cancer cell media compared to the normal cell EVs. We show that both EVs display an EV marker, CD9, while EVs derived from the cancer cells are slightly higher in density. Hyaluronan (HA) is a nonsulfated glycosaminoglycan linked to malignant tumor growth according to recent reports. Interestingly, at the single-vesicle level, colon cancer EVs exhibit significantly increased HA surface densities compared to the normal EVs. Spectroscopic measurements such as Fourier transform infrared (FT-IR), circular dichroism (CD), and Raman spectroscopy unequivocally support the AFM and AFS measurements. To our knowledge, it represents the first report of detecting HA-coated EVs as a potential colon cancer biomarker. Taken together, this sensitive approach will be useful in identifying biomarkers in the early stages of detection and evaluation of cancer.

Hyaluronic Acid and Controlled Release: A Review

Hyaluronic acid (HA) also known as hyaluronan, is a natural polysaccharide—an anionic, non-sulfated glycosaminoglycan—commonly found in our bodies. It occurs in the highest concentrations in the eyes and joints. Today HA is used during certain eye surgeries and in the treatment of dry eye disease. It is a remarkable natural lubricant that can be injected into the knee for patients with knee osteoarthritis. HA has also excellent gelling properties due to its capability to bind water very quickly. As such, it is one the most attractive controlled drug release matrices and as such, it is frequently used in various biomedical applications. Due to its reactivity, HA can be cross-linked or conjugated with assorted bio-macromolecules and it can effectively encapsulate several different types of drugs, even at nanoscale. Moreover, the physiological significance of the interactions between HA and its main membrane receptor, CD44 (a cell-surface glycoprotein that modulates cell–cell interactions, cell adhesion and migration), in pathological processes, e.g., cancer, is well recognized and this has resulted in an extensive amount of studies on cancer drug delivery and tumor targeting. HA acts as a therapeutic but also as a tunable matrix for drug release. Thus, this review focuses on controlled or sustained drug release systems assembled from HA and its derivatives. More specifically, recent advances in controlled release of proteins, antiseptics, antibiotics and cancer targeting drugs from HA and its derivatives were reviewed. It was shown that controlled release from HA has many benefits such as optimum drug concentration maintenance, enhanced therapeutic effects, improved efficiency of treatment with less drug, very low or insignificant toxicity and prolonged in vivo release rates.

Development of solvent-free protocols for obtaining highly substituted maleates of hyaluronic acid and other glycosaminoglycans

Solvent-free protocols using microwave-assisted heating (i) or conventional heating without additives (ii) or adding K₂CO₃ (iii), or triturating at room temperature in the presence of K₂CO₃ (iv) were first used to esterify glycosaminoglycans (GAG) with maleic anhydride. High and low molecular weight hyaluronic acid (HMW and LMW HA), dermatan sulfate (Ds), heparin (HEP) and C6-oxidized HA (carboxy-HA) were used as substrates for maleation. Protocols (i)-(iii) were most effective for obtaining maleates with high DS (1.39-2.47), but had a strong degrading effect on GAG. Protocol (iv) did not have destructive effect, but was suitable for obtaining only HMW HA maleate (DS 0.71-1.15). Primary hydroxyl groups of HA and Ds showed a higher reactivity compared to the secondary ones. A specific feature of the HEP maleation was substitution of N-sulfate groups for N-maleate groups. To demonstrate the potential of the obtained maleates for thiol-ene click-chemical strategies, the reaction with l-cysteine was performed.

Applications of Fourier transform infrared spectroscopy to pharmaceutical preparations

Introduction: Various pharmaceutical preparations are widely used for clinical treatment. Elucidation of the mechanisms of drug release and evaluation of drug efficacy in biological samples are important in drug design and drug quality control.Areas covered: This review classifies recent applications of Fourier transform infrared (FTIR) spectroscopy in the field of medicine to comprehend drug release and diffusion. Drug release is affected by many factors of preparations, such as drug delivery system and microstructure polymorphism. The applications of FTIR imaging and nano-FTIR technique in biological samples lay a foundation for studying drug mechanism in vivo.Expert opinion: FTIR spectroscopy meets the research needs on preparations to understand the processes and mechanisms underlying drug release. The combination of attenuated total reflectance-FTIR imaging and nano-FTIR accompanied by chemometrics is a potent tool to overcome the deficiency of conventional infrared detection. FTIR shows an enormous potential in drug characterization, drug quality control, and bio-sample detection.

Hyaluronic Acid-Coated Nanomedicine for Targeted Cancer Therapy

Hyaluronic acid (HA) has been widely investigated in cancer therapy due to its excellent characteristics. HA, which is a linear anionic polymer, has biocompatibility, biodegradability, non-immunogenicity, non-inflammatory, and non-toxicity properties. Various HA nanomedicines (i.e., micelles, nanogels, and nanoparticles) can be prepared easily using assembly and modification of its functional groups such as carboxy, hydroxy and N-acetyl groups. Nanometer-sized HA nanomedicines can selectively deliver drugs or other molecules into tumor sites via their enhanced permeability and retention (EPR) effect. In addition, HA can interact with overexpressed receptors in cancer cells such as cluster determinant 44 (CD44) and receptor for HA-mediated motility (RHAMM) and be degraded by a family of enzymes called hyaluronidase (HAdase) to release drugs or molecules. By interaction with receptors or degradation by enzymes inside cancer cells, HA nanomedicines allow enhanced targeting cancer therapy. In this article, recent studies about HA nanomedicines in drug delivery systems, photothermal therapy, photodynamic therapy, diagnostics (because of the high biocompatibility), colloidal stability, and cancer targeting are reviewed for strategies using micelles, nanogels, and inorganic nanoparticles.

Preparation and Evaluation of Topically Applied Azithromycin Based on Sodium Hyaluronate in Treatment of Conjunctivitis

Azithromycin (AZI) eye drops containing sodium hyaluronate (SH) were developed to improve the bioavailability of AZI. Interaction between AZI and SH in the AZI-SH formulation was investigated by differential scanning calorimetry, X-ray diffraction, and ¹H-nuclear magnetic resonance spectroscopy analyses. Moreover, advantages of using SH as an excipient were investigated by comparing physiological properties and pharmacokinetic behaviors of SH-containing AZI eye drops with that of hydroxypropyl methylcellulose (HPMC)-containing formulation. In addition, safety of the developed AZI-SH eye drops was evaluated by in vitro 3-(4,5-dimethyl-2-Thiazyl)-2, 5-diphenyl-2H-tetrazolium bromide assay (MTT assay) and neutral red uptake assay as well as in vivo eye irritation test and acute toxicity test. The results indicated that AZI formed a complex with SH under a slightly acidic condition. The area under the curve (AUC) of AZI in SH-containing formulation was 1.58-fold higher (P < 0.01) than that in HPMC-containing formulation due to the interaction between the amine group of AZI and the carboxyl group of SH, despite of the higher viscosity of HPMC-containing formulation. Safety evaluation showed that AZI-SH eye drops caused no obvious eye irritation and acute toxicity. In conclusion, the developed SH-containing AZI formulation possessing advantages of longer retention time and higher drug availability was a promising drug formulation for topical ocular therapy.

Targeted Reinforcement of Macrophage Reprogramming Toward M2 Polarization by IL-4-Loaded Hyaluronic Acid Particles

Alteration of macrophage polarization from inflammatory (M1) to anti-inflammatory (M2) phenotype can have striking implications for the regeneration of injured tissues, treatment of inflammatory diseases, and relief of autoimmune disorders. Although certain cytokines like interleukin (IL)-4 and IL-13 are capable of inducing M2 macrophage polarization, their therapeutic potential in vivo is suffering from low efficacy due to their instability and poor access to target cells. Here, we report the synthesis of IL-4-loaded hyaluronic acid (HA) particle for the targeted delivery of cytokines through the high affinity of HA to CD44 receptors of macrophages. HA carriers composed of low, middle, and high molecular weight (MW) polymers were synthesized using divinyl sulfone (DVS) cross-linking. The MW of HA had a negligible effect on the physicochemical properties and biocompatibility of the macrophages, but as an indicative of M2 polarization, a significant change in the arginase-1 (Arg-1) activity, TNF-α release, and IL-10 secretion was observed for the HA particles prepared with high MW polymers. Therefore, these particles were loaded with IL-4 for simultaneous macrophage targeting and M1 to M2 reprogramming, evidenced by a remarkable increase in the Arg-1 to iNOS ratio, as well as CD163 and CD206 upregulation in the M1 macrophages, which were initially triggered by lipopolysaccharide and interferon-γ.

Microfibrous scaffolds from poly(l-lactide-co-ε-caprolactone) blended with xeno-free collagen/hyaluronic acid for improvement of vascularization in tissue engineering applications

Success of 3D tissue substitutes in clinical applications depends on the presence of vascular networks in their structure. Accordingly, research in tissue engineering is focused on the stimulation of angiogenesis or generation of a vascular network in the scaffolds prior to implantation. A novel, xeno-free, collagen/hyaluronic acid-based poly(l-lactide-co-ε-caprolactone) (PLC/COL/HA) (20/9.5/0.5 w/w/w) microfibrous scaffold was produced by electrospinning. Collagen types I and III, and hyaluronic acid were isolated from human umbilical cords and blended with the GMP grade PLC. When compared with PLC scaffolds the PLC/COL/HA had higher water uptake capacity (103% vs 66%) which may have contributed to the decrease in its Young's Modulus (from 1.31 to 0.89 MPa). The PLC/COL/HA better supported adipose tissue-derived mesenchymal stem cell (AT MSC) adhesion; within 24 h the cell number on the PLC/COL/HA scaffolds was 3 fold higher. Co-culture of human umbilical vein endothelial cells and AT MSCs induced capillary formation on both scaffold types, but the PLC/COL/HA led to formation of interconnected vessels whose total length was 1.6 fold of the total vessel length on PLC. Clinical use of this scaffold would eliminate the immune response triggered by xenogeneic collagen and transmission of animal-borne diseases while promoting a better vascular network formation.

Infrared Spectroscopic Quantification of Methacrylation of Hyaluronic Acid: A Scaffold for Tissue Engineering Applications

Methacrylated hyaluronic acid (MeHA) has been used extensively in tissue engineering and drug delivery applications. The degree of methacrylation (DM) of HA impacts hydrogel crosslinking, which is of pivotal importance for cell interactions. The methacrylation reaction occurs over several hours, and DM is currently assessed post reaction and after dialysis of the solution, using nuclear magnetic resonance (1H NMR) data. Thus, there is little control over exact DM in a specific reaction. Here, infrared (IR) spectroscopy in attenuated total reflection (ATR) mode was investigated as an alternate modality for assessment of the DM of HA hydrogels, including during the reaction progression. Attenuated total reflection is a low-cost technique that is widely available in research and industry labs that can be used online during the reaction process. Strong correlations were achieved with IR-derived peak heights from dialyzed and lyophilized samples at 1708 cm-1 (from the methacrylic ester carbonyl vibration), and 1H NMR values ( R = 0.92, P = 6.56E-11). Additional IR peaks of importance were identified using principal component analysis and resulted in significant correlations with the 1H NMR DM parameter: 1454 cm-1 ( R = 0.85, P = 2.81E-8), 1300 cm-1 ( R = 0.95, P = 4.50E-14), 950 ( R = 0.85, P = 3.55E-8), 856 cm-1 ( R = 0.94, P = 1.20E-12), and 809 cm-1 ( R = 0.93, P = 3.54E-12). A multiple linear regression model to predict 1H NMR-derived DM using the 1708, 1300, and 1200 cm-1 peak heights as independent variables resulted in prediction with an error of 3.2% using dialyzed and lyophilized samples ( P < 0.001). Additionally, a multilinear regression model to predict the DM in undialyzed liquid MeHA samples obtained during the reaction process using similar peak height positions as independent variables resulted in a prediction error of 0.81% ( P < 0.05). Thus, IR spectroscopy can be utilized as an alternate modality to 1H NMR for quantification of the DM of MeHA while sampling either on-line during the methacrylation reaction as well as in post-lyophilized products. This could greatly simplify workflow for tissue engineering and other applications.

Characterizations of hyaluronate-based terpolymeric hydrogel synthesized via free radical polymerization mechanism for biomedical applications

In the present study, a novel terpolymeric hydrogel was developed using sodium hyaluronate (HA), 2-hydroxyethyl acrylate (2-HEA), and poly(ethylene glycol) diacrylate (PEGDA) via free radical polymerization for biomedical applications. To achieve elasticity, swelling ability, porous architecture and sufficient gel strength, hyaluronate was chemically modified by grafting and crosslinking methods using 2-HEA and PEGDA, respectively. The structure and compositions of the fabricated terpolymer (HA-g-p(2-HEA)-x-PEGDA) were verified by FTIR, ¹H HR-MAS-NMR, and TGA analyses. The surface morphology and cross-section of the hydrogel was detected by SEM analysis. The gel nature of terpolymer in aqueous medium at 37 °C was confirmed from swelling study, and rheological experiment. Non-cytotoxicity and biocompatibility of the HA-g-p(2-HEA)-x-PEGDA hydrogel were ascertained by in vitro mouse osteoblastic cells (MC3T3) proliferation, and viability studies. Hematoxylin and eosin Y, and Masson's trichrome stainings were performed to show tissue regeneration ability on the prepared hydrogel. In vitro release results of proangiogenic drug-dimethyloxalylglycine (DMOG), and antibiotics-tetracycline (TCN) showed sustained release behaviour from the prepared hydrogel under different pHs at 37 °C. The mathematical models fitted data imply that both DMOG and TCN release follow first order kinetics, while, the release mechanism is primarily controlled by diffusion as well as erosion process. Finally, the novel biocompatible HA-g-p(2-HEA)-x-PEGDA gel, which showed sustained drugs release, and regeneration ability of extracellular matrix and collagen, could be employed in biomedical applications, especially, for the delivery of DMOG/TCN, and in tissue engineering.

Polycomplexes of Hyaluronic Acid and Borates in a Solid State and Solution: Synthesis, Characterization and Perspectives of Application in Boron Neutron Capture Therapy

In this report, we propose a new polyborate fragment synthesis strategy along the whole chain of the polysaccharide hyaluronic acid (HA) to produce boron neutron capture therapy (BNCT) compounds. Under high pressure and deformatory solid-state conditions, polymolecular system formation takes place due to association of phase-specific transition components into a more or less distinct microscopic organization. Fourier transform infrared (FTIR) spectroscopy shows that HA and polyborates form a network of cyclic polychelate complexes. HA acts as a multidentate ligand using carboxylic and hydroxyl proton donor groups to link oxygen atoms in B⁻O⁻B bonds and borate-anions B⁻O(-): O⁻H···O, O⁻H···(-)O. With free electron pairs in heteroatoms ⁻O(:)···B, ⁻N(:)···B, HA can act simultaneously as an electron donor. Nuclear magnetic resonance (NMR) with ¹³C and ¹H reveals a preserved complex interaction after both solubilizing and attenuating the HA-polyborate system. Stability of the product in water, low cost, ease of synthesis and scalability of manufacturing indicate that HA-polyborate complexes might have advantages over current chemotherapeutic approaches in creating therapeutic agents for BNCT.

Progress in internal/external stimuli responsive fluorescent carbon nanoparticles for theranostic and sensing applications

In the past decade, fluorescent carbon nanoparticles (FNPs) prepared from natural resources and biomaterials have been attractive due to their various properties, such as unique optical properties, great biocompatibility, water dispersion, and facile surface functionalization. Depending on the properties of the carbon sources and the subsequent carbonization processes, internal/external stimuli responsive carbon nanoparticles have been generated that are useful for theranostic and sensing applications. In this review, we highlight the recent developments in the use of FNPs in nanomedicine in great detail, particularly for FNPs responding to internal stimuli, including redox, pH, and enzymes, and external stimuli, including temperature, light, and magnetic fields, for drug delivery and sensing applications. Furthermore, we hope to provide insight that could stimulate further research aiming for unparalleled useful applications. As a result, there are many possibilities that can be explored from this smart material.

Thermo-and pH-sensitive hydrogel membranes composed of poly(N-isopropylacrylamide)-hyaluronan for biomedical applications: Influence of hyaluronan incorporation on the membrane properties

Interpenetrating hydrogel membranes consisting of pH-sensitive hyaluronan (HA) and thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAM) were synthesized using redox polymerization, followed by N,N-methylenebisacrylamide (BIS) and epichlorohydrin (EPI) were added as chemical crosslinkers. The interaction between membrane compositions has been characterized by FTIR spectroscopy and discussed intensively. The result indicates that HA incorporation in membranes increase the gel fraction, swelling uptake, and the flexibility/elasticity of crosslinked membranes, however it reduced oppositely the mechanical elongation of membranes. PNIPAAm-HA hydrogels responded to both temperature and pH changes and the stimuli-responsiveness was reversible. However, in vitro bioevaluation results revealed that the released ampicillin during the burst release time was sharply influenced and increased with increasing HA contents in membranes; afterwards it became sustainable. Whereas, high HA contents in hydrogels unexpectedly impacted negatively on the cells viability, owing to the viscosity of cell culture media changed. A big resistance was observed against microbial growth of Staphylococcus aureus, Salmonella typhi, and Candida albicans in case of pure PNIPAAm hydrogel membranes without HA or ampicillin. However, HA incorporation or the loaded ampicillin in membranes showed unexpected easily microbial growth. The fast release performance with dual pH-thermo-sensitive hydrogels were suggested as promising materials for quick drug carrier in the biomedical field.

Novel moisture-preserving derivatives of hyaluronan resistant to hyaluronidase and protective to UV light

Current studies have revealed the excellent moisture absorption-retention capacity of hyaluronan (HA); however, HA is easily degraded by hyaluronidase on the surface of skin. So, it is very necessary to develop an alternative derivative with low cytotoxicity and resistance to hyaluronidase. Herein, a HA decorated with photocaged groups was synthesized. The moisture absorption-retention capacity and hyaluronidase resistance of photocaged HA (HA-DMNB) and products of HA-DMNB irradiated by ultraviolet for different time (IHA-DMNB), were investigated. Results show that HA-DMNB is more resistant to hyaluronidase than HA, and HA-DMNB could release free carboxyl groups of HA upon ultraviolet to bond with H₂O. More importantly, HA-DMNB was protective against UV light. In addition, HA-DMNB and IHA-DMNB were observed to be nontoxic to HaCat cells. This study indicates that HA-DMNB may be effectively used as a moisture-preserving reagent.

Scaffolds based on hyaluronan and carbon nanotubes gels

Physico-chemical and mechanical properties of hyaluronic acid/carbon nanotubes nanohybrids have been correlated with the proportion of inorganic nanophase and the preparation procedure. The mass fraction of -COOH functionalized carbon nanotubes was varied from 0 to 0.05. Hyaluronic acid was crosslinked with divinyl sulfone to improve its stability in aqueous media and allow its handling as a hydrogel. A series of samples was dried by lyophilization to obtain porous scaffolds whereas another was room-dried allowing the collapse of the hybrid structures. The porosity of the former, together with the tighter packing of hyaluronic acid chains, results in a lower water absorption and lower mechanical properties in the swollen state, because of the easier water diffusion. The presence of even a small amount of carbon nanotubes (mass fraction of 0.05) limits even more the swelling of the matrix, owing probably to hybrid interactions. These nanohybrids do not seem to degrade significantly during 14 days in water or enzymatic medium.

Biosynthetic Polymers as Functional Materials

The synthesis of functional polymers encoded with biomolecules has been an extensive area of research for decades. As such, a diverse toolbox of polymerization techniques and bioconjugation methods has been developed. The greatest impact of this work has been in biomedicine and biotechnology, where fully synthetic and naturally derived biomolecules are used cooperatively. Despite significant improvements in biocompatible and functionally diverse polymers, our success in the field is constrained by recognized limitations in polymer architecture control, structural dynamics, and biostabilization. This Perspective discusses the current status of functional biosynthetic polymers and highlights innovative strategies reported within the past five years that have made great strides in overcoming the aforementioned barriers.

Bromo-Substituted Diketopyrrolopyrrole Derivative with Specific Targeting and High Efficiency for Photodynamic Therapy

Novel photosensitizers with high reactive oxygen species generation and precise targeting to tumors are crucial for photodynamic therapy (PDT). Here, a bromo-substituted diketopyrrolopyrrole derivative (2,5-bis(6-bromohexyl)-3,6-bis(5-bromothiophene-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione)-grafted hyaluronic acid is synthesized, which presents excellent targeting and PDT efficiency both in vitro and in vivo.

Mesoporous Silica Nanoparticles Functionalized with Hyaluronic Acid and Chitosan Biopolymers. Effect of Functionalization on Cell Internalization

Mesoporous silica nanoparticles (MSNs), based on the MCM-41 matrix, were functionalized with amino groups, and then with hyaluronic acid (HA) or chitosan (CHIT) to fabricate bioactive conjugates. The role of the functional groups toward cytotoxicity and cellular uptake was investigated using 3T3 mouse fibroblast cells. A very high biocompatibility of MSN-NH₂, MSN-HA and MSN-CHIT matrices was assessed through the MTS biological assay and Coulter counter evaluation. No significant differences in cytotoxicity data arise from the presence of different functional groups in the investigated MSNs. Fluorescence microscopy experiments performed using fluorescein isothiocyanate-conjugated MSN-NH₂, MSN-HA, and MSN-CHIT, and transmission electron microscopy experiments performed on slices of the investigated systems embedded in epoxy resins give evidence of significant differences due to type of functionalization in terms of cellular uptake and stability of the particles in the biological medium. MSN-NH₂ and MSN-HA conjugates are easily internalized, the uptake of the HA-functionalized MSNs being much higher than that of the -NH₂-functionalized MSNs. Differently, MSN-CHIT conjugates tend to give large aggregates dispersed in the medium or localized at the external surface of the cell membranes. Both fluorescence microscopy and TEM images show that the MSNs are distributed in the cytoplasm of the cells in the case of MSN-NH₂ and MSN-HA, whereas only a few particles are internalized in the case of MSN-CHIT. Flow cytometry experiments confirmed quantitatively the selectively high cellular uptake of MSN-HA particles.

Crosslinked hydrogels based on biological macromolecules with potential use in skin tissue engineering

Zero-length crosslinked hydrogels have been synthesized by covalent linking of three natural polymers (collagen, hyaluronic acid and sericin), in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide. The hydrogels have been investigated by FT-IR spectroscopy, microcalorimetry, in vitro swelling, enzymatic degradation, and in vitro cell viability studies. The obtained crosslinked hydrogels showed a macroporous structure, high swelling degree and in vitro enzymatic resistance compared to uncrosslinked collagen. The in vitro cell viability studies performed on normal human dermal fibroblasts assessed the sericin proliferation properties indicating a potential use of the hydrogels based on collagen, hyaluronic acid and sericin in skin tissue engineering.

Dual-controlled release system of drugs for bone regeneration

Controlled release systems have been noted to allow drugs to enhance their ability for bone regeneration. To this end, various biomaterials have been used as the release carriers of drugs, such as low-molecular-weight drugs, growth factors, and others. The drugs are released from the release carriers in a controlled fashion to maintain their actions for a long time period. Most research has been focused on the controlled release of single drugs to demonstrate the therapeutic feasibility. Controlled release of two combined drugs, so-called dual release systems, are promising and important for tissue regeneration. This is because the tissue regeneration process of bone formation is generally achieved by multiple bioactive molecules, which are produced from cells by other molecules. If two types of bioactive molecules, (i.e., drugs), are supplied in an appropriate fashion, the regeneration process of living bodies will be efficiently promoted. This review focuses on the bone regeneration induced by dual-controlled release of drugs. In this paper, various dual-controlled release systems of drugs aiming at bone regeneration are overviewed explaining the type of drugs and their release materials.

Microstructural analysis of the fast gelling freeze-dried sodium hyaluronate

Although sodium hyaluronate is a very unstable and heat sensitive molecule, it can remain relatively stable during the freeze-drying process. Aqueous sodium hyaluronate (NaHA) gels were prepared and the obtained samples were freeze-dried. The freeze-dried NaHA samples showed fast gelling ability meanwhile preserved their initial viscoelasticity even after reconstitution. The microstructure of gels obtained from raw substance and freeze-dried NaHA samples was characterized with positron annihilation lifetime spectroscopy and X-ray diffraction patterns while their functionality-related macrostructural properties were tested based on their rheological behavior. The presence of phosphate salts improved the formation of ordered supramolecular structure retaining water in the free volume holes of the polymer chains characterized with decreased ortho-positronium lifetime values. This property may be advantageous in the development of a freeze-dried NaHA injection dosage form.

Adsorption of lysozyme on hyaluronic acid functionalized SBA-15 mesoporous silica: a possible bioadhesive depot system

Silica-based ordered mesoporous materials are very attractive matrices to prepare smart depot systems for several kinds of therapeutic agents. This work focuses on the well-known SBA-15 mesoporous silica and lysozyme, an antimicrobial protein. In order to improve the bioadhesion properties of SBA-15 particles, the effect of hyaluronic acid (HA) functionalization on lysozyme adsorption was investigated. SBA-15 samples having high (H-SBA) and low (L-SBA) levels of functionalization were analyzed during the three steps of the preparations: (1) introduction of the -NH2 groups to obtain the SBA-NH2 samples; (2) functionalization with HA to obtain the SBA-HA matrices; (3) adsorption of lysozyme. All silica matrices were characterized through N2-adsorption/desorption isotherms, small-angle X-ray scattering, transmission electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The whole of the experimental data suggests that a high level of functionalization of the silica surface allows for a negligible lysozyme adsorption mainly due to unfavorable electrostatic interactions (H-SBA-NH2) or steric hindrance (H-SBA-HA). A low degree of functionalization of the silica surface brings about a very good performance toward lysozyme adsorption, being 71% (L-SBA-NH2) and 63% (L-SBA-HA) respectively, compared to that observed for original SBA-15. Finally, two different kinetic models--a "pseudo-second order" and a "intraparticle diffusion"--were compared to fit lysozyme adsorption data, the latter being more reliable than the former.