HNO3/H3PO4–NANO2 mediated oxidation of cellulose — preparation and characterization of bioabsorbable oxidized celluloses in high yields and with different levels of oxidation

Preparation and assessment of agar/TEMPO-oxidized bacterial cellulose cryogels for hemostatic applications

In this work, we have demonstrated agar and oxidized bacterial cellulose cryogels as a potential hemostatic dressing material. TEMPO-oxidized bacterial cellulose (OBC) was incorporated into the agar matrix, improving its mechanical and hemostatic properties. The oxidation of bacterial cellulose (BC) was evidenced by chemical characterization studies, confirming the presence of carboxyl groups. The in vitro blood clotting test conducted on agar/OBC composite cryogels demonstrated complete blood clotting within 90 seconds, indicating their excellent hemostatic efficacy. The cryogels exhibited superabsorbent properties with a swelling degree of 4200%, enabling them to absorb large amounts of blood. Moreover, the compressive strength of the composite cryogels was appreciably improved compared to pure agar, resulting in a more stable physical structure. The platelet adhesion test proved the significant ability of the composite cryogels to adhere to and aggregate platelets. Hemocompatibility and cytocompatibility tests have verified the safety of these cryogels for hemostatic applications. Finally, the material exhibited remarkable in vivo hemostatic performance, achieving clotting times of 64 seconds and 35 seconds when tested in the rat tail amputation model and the liver puncture model, respectively. The experiment results were compared with those of commercial hemostat, Axiostat, and Surgispon, affirming the potential of agar/OBC composite cryogel as a hemostatic dressing material.

Polycarboxylate functionalized magnetic nanoparticles Fe3O4@SiO2@CS-COOH: Preparation, characterization, and immobilization of bovine serum albumin

Magnetic nanoparticles with increasing superparamagnetism and magnetic targeting have found widespread application in fields such as food and medicine. In this study, polycarboxylated magnetic nanoparticles (Fe3O4@SiO2@CS-COOH) were prepared by surface functionalizing iron tetraoxide (Fe3O4) nanoparticles with ethylenediaminetetraacetic acid (EDTA) as a modifier. The appropriate degree of functionalization modification was obtained by adjusting the EDTA concentration and the ratio of cross-linking agents. The prepared magnetic nanoparticles were analyzed with structural and property characterization. The results showed that the Fe3O4@SiO2@CS-COOH magnetic nanoparticles prepared with 4 % EDTA and cross-linking agents at a molar ratio of 3:4 were uniform in particle size, with an average size of roughly 7 nm, and possessed an abundant carboxylate content (310.8064 μmol/g) and a high magnetization intensity (35.05 emu/g). As a model protein, bovine serum albumin (BSA) was immobilized on the surface of magnetic particles. The largest amount of immobilized protein was 500.4376 mg BSA/g at pH 4.0 and no extra salt ions. According to molecular docking simulations, its immobilization was due to the interaction of amino and carboxyl groups at the Fe3O4@SiO2@CS-COOH/BSA interface. Fe3O4@SiO2@CS-COOH possesses a large number of carboxyl groups, strong protein immobilization, and magnetic responsiveness, which may have potential applications in biomedical and food fields.

Development of tissue-engineered vascular grafts from decellularized parsley stems

Cardiovascular diseases are mostly associated with narrowing or blockage of blood vessels, and it is the most common cause of death worldwide. The use of vascular grafts is a promising approach to bypass or replace the blocked vessels for long-term treatment. Although autologous arteries or veins are the most preferred tissue sources for vascular bypass, the limited presence and poor quality of autologous vessels necessitate seeking alternative biomaterials. Recently, synthetic grafts have gained attention as an alternative to autologous grafts. However, the high failure rate of synthetic grafts has been reported primarily due to thrombosis, atherosclerosis, intimal hyperplasia, or infection. Thrombosis, the main reason for failure upon implantation, is associated with damage or absence of endothelial cell lining in the vascular graft's luminal surface. To overcome this, tissue-engineered vascular grafts (TEVGs) have come into prominence. Alongside the well-established scaffold manufacturing techniques, decellularized plant-based constructs have recently gained significant importance and are an emerging field in tissue engineering and regenerative medicine. Accordingly, in this study, we demonstrated the fabrication of tubular scaffolds from decellularized parsley stems and recellularized them with human endothelial cells to be used as a potential TEVG. Our results suggested that the native plant DNA was successfully removed, and soft tubular biomaterials were successfully manufactured via the chemical decellularization of the parsley stems. The decellularized parsley stems showed suitable mechanical and biological properties to be used as a TEVG material, and they provided a suitable environment for the culture of human endothelial cells to attach and create a pseudo endothelium prior to implantation. This study is the first one to demonstrate the potential of the parsley stems to be used as a potential TEVG biomaterial.

Facile fabrication of reusable starch sponge with adjustable crosslinked networks for efficient nest-trap and in situ photodegrade methylene blue

The fabrication of reusable natural polysaccharide sponges with nanoscale dispersed photocatalysts to achieve robust photocatalytic efficiency is desirable yet challenging. Herein, inspired by the nesting behavior when fishing, we designed reusable starch sponge with chemically anchored nano-ZnO into carboxylated starch matrix by thermoplastic interfacial reactions and solvent replacement for absorbing and photodegrading methylene blue (MB) in situ. The plasticization and interfacial reactions promoted a simultaneous increase in the reactivity of the starch hydroxyl/carboxyl groups and the specific surface area of ZnO. Meanwhile, the crosslinked networks of starch sponge could be adjusted by varying the ZnO and carboxylic groups contents. The results of photodegradation experiments revealed the recyclable closed-loop process of attraction-trapping-photodegradation of MB was successfully realized, achieving the effect of killing three birds with one stone. The reusable starch sponge with homogeneous dispersion of nano-ZnO by constructing three-dimensional porous channels possessed the high enrichment capacity and the remarkable photocatalysis efficiency with 150 mg/L ZnO. Under UV irradiation, the starch sponge degraded 97 % of MB with 1.67 × 10-3 min-1 photodegradation rate constant even after five cycles, which exceeded most existing photocatalytic systems. Overall, the reusable starch sponge with adjustable structure provided new insights for multifunctional bio-based photocatalyst loading systems.

Oxidized pullulan exhibits potent antibacterial activity against S. aureus by disrupting its membrane integrity

The capability of bacteria to withstand the misuse of antibiotics leads to the generation of multi-drug resistant strains, posing a new challenge to curb wound infections. The biological macromolecules, due to their biocompatibility, biodegradability, and antimicrobial properties, have been explored for a variety of antimicrobial and therapeutic purposes. This work reports that a single-step oxidation of pullulan polymer leads to the formation of oxidized pullulan (o-pullulan), which shows striking antibacterial and antibiofilm activities against the Gram-positive bacteria, Staphylococcus aureus, implicated in wound-related infections. Oxidation of pullulan generates 28 % aldehyde groups (3.462 mmol/g) which exerted 97 % bactericidal activity against S. aureus by targeting cell wall-associated membrane protein SpA (Staphylococcal protein A). The molecular docking, gene silencing, and fluorescence quenching studies revealed a direct binding of o-pullulan with the B and C domains of SpA, which alters the membrane potential and inhibits Ca2+-Mg2+-ATPase pumps. O-pullulan also exhibited scavenging activity against intracellular reactive oxygen species (ROS), and non-immunotoxic activity and was found to be non-toxic to mammalian cells. Thus, o-pullulan shows great promise as an antimicrobial polymer against S. aureus for chronic wound management.

Intelligent high-tech coating of natural biopolymer layers

Polymeric materials play a vital role in our daily life, but the growing concern for the environment demands economical and natural biopolymers that can be cross-linked to create technologically innovative lightweight materials. Their cellular matrix with extreme flexibility makes them highly acceptable for application prospects in material science, engineering, and biomedical applications. Furthermore, their biocompatibility, mechanical properties, and structural diversity provide a gateway to research them to form technologically important materials. In the light of the same, the review covers cellulose derivatives. The first section of the study covers the general properties and applications of cellulose and its derivatives. Then, the biopolymers are characterised based on their dielectric properties, crystallinity, rheology, and mechanical properties. An in-depth analysis of the diffuse process of swelling and dissolution followed by a brief discussion on diffusion and diffusion of crosslinking has been done. The review also covers a section on swelling and swelling kinetics of carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC). The examination of all the aforementioned parameters gives an insight into the future aspects of the biopolymers. Lastly, the study briefly covers some preferred choices of cross-linking agents and their effect on the biopolymers.

Recycling of Brewer's Spent Grain as a Biosorbent by Nitro-Oxidation for Uranyl Ion Removal from Wastewater

Developing biosorbents derived from agro-industrial biomass is considered as an economic and sustainable method for dealing with uranium-contaminated wastewater. The present study explores the feasibility of oxidizing a representative protein-rich biomass, brewer's spent grain (BSG), to an effective and reusable uranyl ion adsorbent to reduce the cost and waste generation during water treatment. The unique composition of BSG favors the oxidation process and yields in a high carboxyl group content (1.3 mmol/g) of the biosorbent. This makes BSG a cheap, sustainable, and suitable raw material independent from pre-treatment. The oxidized brewer's spent grain (OBSG) presents a high adsorption capacity of U(VI) of 297.3 mg/g (c 0(U) = 900 mg/L, pH = 4.7) and fast adsorption kinetics (1 h) compared with other biosorbents reported in the literature. Infrared spectra (Fourier transform infrared), 13C solid-state nuclear magnetic resonance spectra, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis were employed to characterize the biosorbents and reveal the adsorption mechanisms. The desorption and reusability of OBSG were tested for five cycles, resulting in a remaining adsorption of U(VI) of 100.3 mg/g and a desorption ratio of 89%. This study offers a viable and sustainable approach to convert agro-industrial waste into effective and reusable biosorbents for uranium removal from wastewater.

Current Advances in the Development of Decellularized Plant Extracellular Matrix

An imbalance exists between the supply of organs for transplantation and the number of patients in the donor transplant waiting lists. Current use of autologous, synthetic, and animal-derived grafts for tissue replacement is limited by the low availability, poor biocompatibility, and high cost. Decellularized plant scaffolds with remarkable physical similarities to human organs have recently emerged and have been found to present favorable characteristics that make them suitable as an alternative biomaterial, such as a superficial surface area, excellent water transport and retention, pre-existing vascular networks, interconnected porosity, and a wide range of mechanical properties. In addition to their unique and superior biocompatibility, plant-derived scaffolds present the advantages of low production cost, no ethical or supply constraints, simple operation and suitability for large-scale production and research. However, there are still some problems and deficiencies in this field, such as immature decellularization standards and methods, insufficient research on the biocompatibility of plant extracellular matrix. At present, research on decellularized plant extracellular matrix is still in its infancy, and its applicability to tissue engineering needs to be further improved. In this review, the current research progress on decellularized plant scaffolds is reviewed, the problems to be solved and future research directions are discussed.

Structure and properties of oxycellulose fabric crosslinked with soy protein

Cotton is an important renewable biopolymer with extensive applications in various fields including textiles. In the current study a soy protein (SP) crosslinked cotton fabric (SPCCF) was prepared through the reaction of carboxyl cotton fabric with soy protein without using crosslinking agents. FTIR analysis of SPCCF samples indicated that carboxyl groups in oxycellulose fabric have reacted with amino groups of SP to give the corresponding C-N bond, that was also reconfirmed by XPS spectra and TGA/DTG analyses of the grafted fabrics. The resulting SPCCF fabrics acquired under the optimized conditions exhibited the improved tensile strength and capillary effect as compared to the oxidized cotton fabric. The ungrafted and grafted fabrics were further evaluated for dyeing property, as a result, the SPCCF fabrics showed markedly improved colour strength when dyed with acid dyes. The fastness properties of dyeability for the dyed SPCCF fabrics were also good compared with that of ungrafted fabrics by dyeing. Shikonin as a kind of Chinese medicine was found to immobilize on the SPCCF fabric through treatment with shikonin aqueous solution, such fabric displayed effective antibacterial activities against both gram-positive and gram-negative bacteria with durability of 30 washes. These results suggest that the SPCCF can be suitable for medical protective textiles by immobilizing drugs.

A novel antimicrobial-containing nanocellulose scaffold for regenerative endodontics

Objectives

The aim of this study was to evaluate bacterial nanocellulose (BNC) membranes incorporated with antimicrobial agents regarding cytotoxicity in fibroblasts of the periodontal ligament (PDLF), antimicrobial activity, and inhibition of multispecies biofilm formation.

Materials and Methods

The tested BNC membranes were BNC + 1% clindamycin (BNC/CLI); BNC + 0.12% chlorhexidine (BNC/CHX); BNC + nitric oxide (BNC/NO); and conventional BNC (BNC; control). After PDLF culture, the BNC membranes were positioned in the wells and maintained for 24 hours. Cell viability was then evaluated using the MTS calorimetric test. Antimicrobial activity against Enterococcus faecalis, Actinomyces naeslundii, and Streptococcus sanguinis (S. sanguinis) was evaluated using the agar diffusion test. To assess the antibiofilm activity, BNC membranes were exposed for 24 hours to the mixed culture. After sonicating the BNC membranes to remove the remaining biofilm and plating the suspension on agar, the number of colony-forming units (CFU)/mL was determined. Data were analyzed by 1-way analysis of variance and the Tukey, Kruskal-Wallis, and Dunn tests (α = 5%).

Results

PDLF metabolic activity after contact with BNC/CHX, BNC/CLI, and BNC/NO was 35%, 61% and 97%, respectively, compared to BNC. BNC/NO showed biocompatibility similar to that of BNC (p = 0.78). BNC/CLI showed the largest inhibition halos, and was superior to the other BNC membranes against S. sanguinis (p < 0.05). The experimental BNC membranes inhibited biofilm formation, with about a 3-fold log CFU reduction compared to BNC (p < 0.05).

Conclusions

BNC/NO showed excellent biocompatibility and inhibited multispecies biofilm formation, similarly to BNC/CLI and BNC/CHX.

Fabrication of oxidized bacterial cellulose by nitrogen dioxide in chloroform/cyclohexane as a highly loaded drug carrier for sustained release of cisplatin

Carboxylated bacterial cellulose (OBC) was fabricated by oxidation with nitrogen dioxide in chloroform/cyclohexane and employed as a carrier for sustained release of antitumor substance cisplatin (CDDP). The influence of removing water method, solvent used in the synthesis, concentration of N₂O₄, and duration of the oxidation on content of carboxyl groups in reaction products was established. Due to the possibility of nitrogen dioxide to penetrate into cellulose crystallites, the carboxyl group content of the OBC reaches high values up to 4 mmol/g. In vitro degradation of OBC was determined under simulated physiological conditions. The immobilization of CDDP on OBC was studied in detail. The initial burst release of the drug from the polymer was depressed. The cytotoxicity of CDDP-loaded OBC was evaluated with HeLa cells. The unique structure and properties of OBC make it a great candidate as drug delivery carrier.

Agar quality promotion prepared by desulfation with hydrogen peroxide

The modified agars were prepared using H₂O₂ in ethanol solution at appropriate pH conditions. Some interesting physical and chemical properties of modified agar were determined and characterized compared with those of raw agar, and the underlying mechanisms were preliminarily studied. Results showed that the maximum gel strength of the modified agar was 1068 g/cm², which increased by 30.9% compared with that of raw agar (816 g/cm²), and the minimum sulfate content of the modified agar was 0.21%, which decreased by 73.4% compared with that of raw agar (0.79%). Moreover, the viscosity, molecular weight, gelling temperature and melting temperature all decreased, whereas the whiteness and transparency increased after modification. Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis indicated that the spatial structure of agar have changed after treated with H₂O₂. Taken together, the results demonstrated that the desulfation of agar with H₂O₂ is a promising approach with practical significance.

Influence of Different Pretreatments on the Antibacterial Properties of Chitosan Functionalized Viscose Fabric: TEMPO Oxidation and Coating with TEMPO Oxidized Cellulose Nanofibrils

The main objective of this study was to obtain chitosan functionalized viscose fabric with improved antibacterial properties and washing durability. In this regard carboxyl and aldehyde groups, as binding points for irreversible chitosan attachment into/onto viscose fabric, were introduced by two different pretreatments: 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) oxidation and coating with TEMPO oxidized cellulose nanofibrils (TOCN). The Fourier transform infrared spectroscopy, elemental analysis, zeta potential measurements, scanning electron microscopy, breaking strength and antibacterial testing were used to evaluate the influence of these pretreatments on chitosan binding, but also on chemical, electrokinetic, morphological, mechanical and antibacterial properties of pretreated and chitosan functionalized viscose fabrics. Washing durability of chitosan functionalized viscose was monitored through changes in the chitosan content, electrokinetic and antibacterial properties after multiple washing. TOCN coating improves mechanical properties of fabric, while TEMPO oxidation deteriorates them. The results show that both pretreatments improve chitosan adsorption and thus antibacterial properties, which are highly durable to washing. After five washings, the chitosan functionalized pretreated viscose fabrics preserve their antibacterial activity against Staphylococcus aureus, while antibacterial activity against Escherichia coli was lost. TOCN coated and chitosan functionalized viscose fabric is a high value-added product with simultaneously improved antibacterial and mechanical properties, which may find application as medical textiles.

Cytotoxicity, bactericidal and hemostatic evaluation of oxidized cellulose microparticles: Structure and oxidation degree approach

Oxidized cellulose is the most used hemostatic materials in clinical applications. In addition to its perfect hemostatic efficiency, it is degradable under in vivo conditions and supremely prevents bacterial growth. On the other hand, one of the drawbacks of the oxidized cellulose is cytotoxicity due to the strongly acidic nature during degradation. There is a number of commercially available oxidized cellulose products which are derived from regenerated and non-regenerated cellulose. On the other hand, the effect of oxidation degree and structure (regenerated or non-regenerated) on product efficiency is undetermined. Moreover, oxidation degree which is primary factor for both bactericidal and hemostatic efficiency is also crucial for assessment of the product. In this study, oxidized cellulose versus oxidized regenerated cellulose microparticles with various oxidation degree was produced and characterized. Comparative studies were conducted in terms of bactericidal and hemostatic efficiencies in addition to cytotoxicity. The results could be a reference for the optimized oxidized cellulose product for the hemostatic applications.

Synthesis and Characterization of Nanofiber of Oxidized Cellulose from Nata De Coco

Oxidized cellulose (OC) nanofiber was successfully prepared from the dry sheet of Nata De Coco (DNDC) using the mixture system of HNO3/H3PO4–NaNO2for the first time. The carboxyl content of the OC was investigated at different conditions (HNO3/H3PO4ratios, reaction times, and reaction temperatures). The results revealed that the carboxyl content of the OC increased along with the reaction time, which yielded 0.6, 14.8, 17.5, 20.9, 21.0, and 21.0% after 0, 6, 12, 36, and 48 hours, respectively. The reaction yields of the OC ranged between 79% and 85% when using HNO3/H3PO4ratio of 1 : 3, 1.4% wt of NaNO2at 30°C at different reaction times. From the structural analysis, the OC products showed a nanofibrous structure with a diameter of about 58.3–65.4 nm. The Fourier transform infrared spectra suggested the formation of carboxyl groups in the OC after oxidation reaction. The crystallinity and crystalline index decreased with an increase of reaction time. The decrease of crystallinity from oxidation process agreed with the decrease of degree of polymerization from the hydrolysis ofβ-1,4-glycosidic linkages in the cellulose structure. The thermal gravimetric analysis results revealed that the OC products were less thermally stable than the raw material of DNDC. In addition, the OC products showed blood agglutinating property by dropping blood on the sample along with excellent antibacterial activity.

Effect of molecular weight on the ability of guar gum to enhance "weak gel" rheology of microdispersed oxidised cellulose (MDOC)

MDOC comprises small, essentially insoluble, particles which associate to form "weak gel" networks at concentrations above ∼4wt%. Association is promoted by guar gum, causing an increase in G' at low levels of addition and a decrease at higher concentrations, due to excessive aggregation of the MDOC particles. For guar gum samples with molecular weights ranging from ∼60 to ∼1800kDa, we found that the concentration required to give maximum G' for 5wt% dispersions of MDOC increased systematically from ∼0.005wt% for the lowest molecular weight to ∼0.3wt% for the highest. We propose that guar gum drives self-association of MDOC to reduce enthalpically-unfavourable (segregative) interactions between the two materials, and that large coils are less effective than smaller ones because a higher proportion of chain sequences are buried in the interior of the coil, where they cannot make segmental contacts with the MDOC particles.

A Simple Approach to Prepare Carboxycellulose Nanofibers from Untreated Biomass

A simple approach was developed to prepare carboxycellulose nanofibers directly from untreated biomass using nitric acid or nitric acid-sodium nitrite mixtures. Experiments indicated that this approach greatly reduced the need for multichemicals, and offered significant benefits in lowering the consumption of water and electric energy, when compared with conventional multiple-step processes at bench scale (e.g., TEMPO oxidation). Additionally, the effluent produced by this approach could be efficaciously neutralized using base to produce nitrogen-rich salts as fertilizers. TEM measurements of resulting nanofibers from different biomasses, possessed dimensions in the range of 190-370 and 4-5 nm, having PDI = 0.29-0.38. These nanofibers exhibited lower crystallinity than untreated jute fibers as determined by TEM diffraction, WAXD and ¹³C CPMAS NMR (e.g., WAXD crystallinity index was ∼35% for nanofibers vs 62% for jute). Nanofibers with low crystallinity were found to be effective for removal of heavy metal ions for drinking water purification.

Optimization of cellulose and sugarcane bagasse oxidation: Application for adsorptive removal of crystal violet and auramine-O from aqueous solution

Cellulose (Cel) and sugarcane bagasse (SB) were oxidized with an H₃PO₄-NaNO₂ mixture to obtain adsorbent materials with high contents of carboxylic groups. The oxidation reactions of Cel and SB were optimized using design of experiments (DOE) and response surface methodology (RSM). The optimized synthesis conditions yielded Cox and SBox with 4.8mmol/g and 4.5mmol/g of carboxylic acid groups, respectively. Cox and SBox were characterized by FTIR, TGA, PZC and solid-state ¹³C NMR. The adsorption of the model cationic dyes crystal violet (CV) and auramine-O (AO) on Cox and SBox in aqueous solution was investigated as a function of the solution pH, the contact time and the initial dye concentration. The adsorption of CV and AO on Cox was described by the Elovich equation and the pseudo-first-order kinetic model respectively, while the adsorption of CV and AO on SBox was described by the pseudo-second-order kinetic model. Adsorption isotherms were well fitted by the Langmuir and Konda models, with maximum adsorption capacities (Q_max) of 1117.8mg/g of CV and 1223.3mg/g of AO on Cox and 1018.2mg/g of CV and 682.8mg/g of AO on SBox. Desorption efficiencies were in the range of 50-52% and re-adsorption capacities varied from 65 to 81%, showing the possibility of reuse of both adsorbent materials.

Structure and properties of silk fibroin grafted carboxylic cotton fabric via amide covalent modification

A novel eco-friendly production of silk fibroin-grafted carboxylic cotton fabrics without using any crosslinking agents was developed via the reaction of silk fibroin with oxidized cotton. The effect of reaction parameters on mechanical properties of oxidized fabrics and graft add-on of silk fibroin in grafted fabrics was examined. The results showed that appropriate oxidation time of HNO₃/H₃PO₄-NaNO₂ mixture and grafting time of fibroin were 45min and 2h respectively. FTIR analysis of grafted sample indicated that the CN amido bond was generated through the reaction between primary amines in silk fibroin and carboxyl groups in oxidized cotton, which was further confirmed by XPS spectra. The grafted fabrics were also evaluated for physical properties like tensile strength, wrinkle recovery angle, moisture regain and yellowness index. Cactus flavonoid coated on grafted fabric through treatment with flavonoid extract of cactus, such treated fabric exhibited a highly inhibitory effect against both Staphylococcus aureus and Escherichia coli bacteria.

Novel electrospun gelatin/oxycellulose nanofibers as a suitable platform for lung disease modeling

Novel hydrolytically stable gelatin nanofibers modified with sodium or calcium salt of oxycellulose were prepared by electrospinning method. The unique inhibitory effect of these nanofibers against Escherichia coli bacteria was examined by luminometric method. Biocompatibility of these gelatin/oxycellulose nanofibers with eukaryotic cells was tested using human lung adenocarcinoma cell line NCI-H441. Cells firmly adhered to nanofiber surface, as determined by scanning electron microscopy, and no signs of cell dying were detected by fluorescent live/dead assay. We propose that the newly developed gelatin/oxycellulose nanofibers could be used as promising scaffold for lung disease modeling and anti-cancer drug testing.

Effect of selective oxidation of bacterial cellulose on degradability in phosphate buffer solution and their affinity for epidermal cell attachment

Oxidized bacterial cellulose showed the 3D nano-fibrils structure of BC. The mass loss and degradation rate of OBC were much higher than those of BC. When immersed in PBS, OBC degraded gradually. Cell-adhesion and proliferation studies revealed that OBC had excellent cellular affinity.

A chlorhexidine-loaded biodegradable cellulosic device for periodontal pockets treatment

Absorbent points widely used in endodontic therapy were transformed into bioresorbable chlorhexidine delivery systems for the treatment of the periodontal pocket by preventing its recolonization by the subgingival microflora. These paper points (PPs) were first oxidized to promote their resorption, then grafted with β-cyclodextrin (CD) or maltodextrin (MD) in order to achieve sustained delivery of chlorhexidine. We investigated the oxidation step parameters through the time of reaction and the nitric and phosphoric acid ratios in the oxidizing mixture, and then the dextrin grafting step parameters through the time and temperature of reaction. A first selection of the appropriate functionalization parameters was undertaken in relation to the degradation profile kinetics of the oxidized (PPO) and oxidized-grafted samples (PPO-CD and PPO-MD). Samples were then loaded with chlorhexidine digluconate (digCHX), a widely used antiseptic agent in periodontal therapy. The release kinetics of digCHX from PPO-CD and PPO-MD samples were compared to PP, PPO and to PerioChip(®) (a commercial digCHX containing gelatine chip) in phosphate buffered saline (pH 7.4) by ultraviolet spectrophotometry. The cytocompatibility of the oxidized-grafted PP was demonstrated by cell proliferation assays. Finally, the disc diffusion test from digCHX loaded PPO-MD samples immersed in human plasma was developed on pre-inoculated agar plates with four common periodontal pathogenic strains: Fusobacterium nucleatum, Prevotella melaninogenica, Aggregatibacter actinomycetem comitans and Porphyromonas gingivalis. To conclude, the optimized oxidized-dextrin-grafted PPs responded to our initial specifications in terms of resorption and digCHX release rates and therefore could be adopted as a reliable complementary periodontal therapy.

Oxycellulose beads with drug exhibiting pH-dependent solubility

The aim of this study was to develop novel hydrogel-based beads and characterize their potential to deliver and release a drug exhibiting pH-dependent solubility into distal parts of gastrointestinal (GI) tract. Oxycellulose beads containing diclofenac sodium as a model drug were prepared by the ionotropic external gelation technique using calcium chloride solution as the cross-linking medium. Resulting beads were characterized in terms of particle shape and size, encapsulation efficacy, swelling ability and in vitro drug release. Also, potential drug-polymer interactions were evaluated using Fourier transform infrared spectroscopy. The particle size was found to be 0.92-0.96 mm for inactive (oxycellulose only) and 1.47-1.60 mm for active (oxycellulose-diclofenac sodium) beads, respectively. In all cases, the sphericity factor was between 0.70 and 0.81 with higher values observed for samples containing higher polymer and drug concentrations. The swelling of inactive beads was found to be strongly influenced by the pH and composition (i.e. Na(+) concentration) of the selected media (simulated gastric fluid vs. phosphate buffer pH 6.8). The encapsulation efficiency of the prepared particles ranged from 58% to 65%. Results of dissolution tests showed that the drug loading inside of the particles influenced the rate of its release. In general, prepared particles were able to release the drug within 12-16 h after a lag time of 4 h. Fickian diffusion was found as the predominant drug release mechanism. Thus, this novel particulate system showed a good potential to deliver drugs specifically to the distal parts of the human GI tract.

Oxidized cellulose binding to allergens with a carbohydrate-binding module attenuates allergic reactions

Grass and mite allergens are of the main causes of allergy and asthma. A carbohydrate-binding module (CBM) represents a common motif to groups I (β-expansin) and II/III (expansin-like) grass allergens and is suggested to mediate allergen-IgE binding. House dust mite group II allergen (Der p 2 and Der f 2) structures bear strong similarity to expansin's CBM, suggesting their ability to bind carbohydrates. Thus, this study proposes the design of a carbohydrate-based treatment in which allergen binding to carbohydrate particles will promote allergen airway clearance and prevent allergic reactions. The aim of the study was to identify a polysaccharide with high allergen-binding capacities and to explore its ability to prevent allergy. Oxidized cellulose (OC) demonstrated allergen-binding capacities toward grass and mite allergens that surpassed those of any other polysaccharide examined in this study. Furthermore, inhalant preparations of OC microparticles attenuated allergic lung inflammation in rye grass-sensitized Brown Norway rats and OVA-sensitized BALB/c mice. Fluorescently labeled OC efficiently cleared from the mouse airways and body organs. Moreover, long-term administration of OC inhalant to Wistar rats did not result in toxicity. In conclusion, many allergens, such as grass and dust mite, contain a common CBM motif. OC demonstrates a strong and relatively specific allergen-binding capacity to CBM-containing allergens. OC's ability to attenuate allergic inflammation, together with its documented safety record, forms a firm basis for its application as an alternative treatment for prevention and relief of allergy and asthma.