scholarly journals Development of a topical tissue cross-linking solution using sodium hydroxymethylglycinate (SMG): viscosity effect

2020 ◽  
Vol 40 (1) ◽  
Author(s):  
Jaya Mehta ◽  
Anna Takaoka ◽  
Mariya Zyablitskaya ◽  
Takayuki Nagasaki ◽  
David C. Paik
Keyword(s):  
Contact Time ◽  
Ex Vivo ◽  
Hydroxypropyl Methylcellulose ◽  
Cross Linking ◽  
Drug Penetration ◽  
Scanning Calorimetry ◽  
Ocular Tissues ◽  
Formulation Factors ◽  
The Cross ◽  
Porcine Cornea

Abstract Hyperviscosity agents are commonly used in ophthalmic formulations for improving corneal drug penetration by increasing tissue contact time. One such viscosity agent is hydroxypropyl methylcellulose (HPMC). HPMC has been used in riboflavin solutions for photochemical UVA cross-linking (CXL). Sodium hydroxymethylglycinate (SMG) is a small molecule formaldehyde releaser that can function as a therapeutic tissue cross-linker for corneal and scleral applications. The present study was undertaken in order to study formulation factors using HPMC and SMG that could positively influence the cross-linking effect in these ocular tissues. Formulations containing 10 mM SMG and 100 mM sodium bicarbonate were prepared with varying HPMC concentrations from 0 to 4.4%. Their cross-linking effects on porcine and rabbit eyes were measured using differential scanning calorimetry (DSC), expressed as the change/difference in melting temperature (ΔTm) compared with the control. SMG in 4.4% HPMC solution resulted in ΔTm of 6.3 ± 1.21, while other concentration showed no differences in Tm shift on porcine cornea. In ex vivo rabbit cornea, there was a trend toward an increasing cross-linking effect with higher viscosity albeit mild differences. While a significant Tm shift was observed in porcine and rabbit sclera, there was no difference in effect of cross-linking between four HPMC concentrations. Increasing the HPMC concentration does not negatively affect the cross-linking efficacy attributed by SMG and could still be a positive cross-linking enhancer by virtue of increasing tissue contact time in a dynamic biological system. This information will be useful for planning further animal and human studies.

Preparation and Application of Electrospinning Membranes of Thermoplastic Carboxymethyl Cellulose/PLA for Removal of Cu2+ from Aqueous Solutions

2012 ◽  
Vol 724 ◽  
pp. 61-64
Author(s):  
Ying Li ◽  
Xiao Yan Lin ◽  
Zhe Chen ◽  
Xue Guang Luo ◽  
Wei Li Zuo
Keyword(s):  
Tensile Strength ◽  
Aqueous Solutions ◽  
Removal Efficiency ◽  
Composite Membrane ◽  
Carboxymethyl Cellulose ◽  
Contact Time ◽  
Electrospinning Process ◽  
Cross Linking ◽  
Initial Concentration ◽  
The Cross

A composite membrane of thermoplastic carboxymethyl cellulose (TCMC) /PLA was prepared by electrospinning process, and crossliked by epichlorohydrin solution at different temperature. The cross-linking temperature was optimized by characterizing the morphology and tensile strength of the film. The optimal cross-linking temperature was 50°C. A composite membrane was used to remove Cu2+ from aqueous solutions, and the effects of initial concentration of Cu2+ and contact time on the removal efficiency of Cu2+ were investigated. The removal efficiency of Cu2+ was 13.78%, at the initial concentration of 40 mg·L-1 and contact time of 30s.

Impact of Corneal Cross-linking on Drug Penetration in an Ex Vivo Porcine Eye Model

Cornea ◽  
2012 ◽  
Vol 31 (3) ◽  
pp. 222-226 ◽  
Author(s):  
Markus Tschopp ◽  
Johannes Stary ◽  
Beatrice E Frueh ◽  
Wolfgang Thormann ◽  
Julie De Smet ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Cross Linking ◽  
Drug Penetration ◽  
Eye Model

Depth- and direction-dependent changes in solute transport following cross-linking with riboflavin and UVA light in ex vivo porcine cornea

2021 ◽  
Vol 205 ◽  
pp. 108498
Author(s):  
R. Glenn Hepfer ◽  
Peng Chen ◽  
Changcheng Shi ◽  
Karolinne M. Rocha ◽  
George O. Waring ◽  
...  
Keyword(s):  
Solute Transport ◽  
Ex Vivo ◽  
Cross Linking ◽  
Uva Light ◽  
Porcine Cornea

scholarly journals Chlorhexidine Mucoadhesive Buccal Tablets: The Impact of Formulation Design on Drug Delivery and Release Kinetics Using Conventional and Novel Dissolution Methods

2021 ◽  
Vol 14 (6) ◽  
pp. 493
Author(s):  
Enas Al-Ani ◽  
David Hill ◽  
Khalid Doudin
Keyword(s):  
Drug Release ◽  
Ex Vivo ◽  
Release Kinetics ◽  
Hydroxypropyl Methylcellulose ◽  
In Vitro Release ◽  
Poloxamer 407 ◽  
Oropharyngeal Candidiasis ◽  
Scanning Calorimetry ◽  
Buccal Tablets ◽  
The Impact

Oropharyngeal candidiasis (OPC) is a mucosal infection caused by Candida spp., and it is common among the immunocompromised. This condition is mainly treated using oral antifungals. Chlorhexidine (CHD) is a fungicidal and is available as a mouth wash and oral gel. It is used as an adjuvant in the treatment of OPC due to the low residence time of the current formulations. In this study, its activity was tested against C. albicans biofilm and biocompatibility with the HEK293 human cell line. Then, it was formulated as mucoadhesive hydrogel buccal tablets to extend its activity. Different ratios of hydroxypropyl methylcellulose (HPMC), poloxamer 407 (P407), and three different types of polyols were used to prepare the tablets, which were then investigated for their physicochemical properties, ex vivo mucoadhesion, drug release profiles, and the kinetics of drug release. The release was performed using Apparatus I and a controlled flow rate (CFR) method. The results show that CHD is biocompatible and effective against Candida biofilm at a concentration of 20 µg/mL. No drug excipient interaction was observed through differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The increase in P407 and polyol ratios showed a decrease in the swelling index and an increase in CHD in vitro release. The release of CHD from the selected formulations was 86–92%. The results suggest that chlorhexidine tablets are a possible candidate for the treatment of oropharyngeal candidiasis.

A Hydroxyapatite-Collagen Composite Useful to Make Bioresorbable Scaffolds for Bone Reconstruction

2010 ◽  
Vol 76 ◽  
pp. 133-138 ◽  
Author(s):  
Giulio D. Guerra ◽  
Caterina Cristallini ◽  
Elisabetta Rosellini ◽  
Niccoletta Barbani
Keyword(s):  
Weight Ratio ◽  
Average Diameter ◽  
Cross Linking ◽  
Bone Reconstruction ◽  
Scanning Calorimetry ◽  
Bioresorbable Scaffolds ◽  
Micro Particles ◽  
Ft Ir ◽  
The Cross ◽  
The Stability

Composites between hydroxyapatite (HA) and collagen (Col) may be used to make bioresorbable scaffolds for bone reconstruction. A suspension of micro-particles (average diameter ≅ 30 µm) of HA annealed at 1100°C in Col solution (80:20 HA to Col weight ratio) was manufactured in films by casting, and then some films were cross-linked by glutaraldehyde vapours. Cross-linked sponges were obtained by treating the suspension with transglutaminase, and by lyophilizing the so obtained gel. Characterization by scanning electron microscopy, water sorption test, Col release in water, thermogravimetric analysis and differential scanning calorimetry shows that the cross-linking enhances the stability of the composite. Conversely, neither the interactions between HA and Col, detected by spotlight FT-IR, nor the degradation by collagenase, which is a requirement for the bioresorbibility, are affected by the cross-linking.

Fast Dissolving Sublingual Strips: A Novel Approach for the Delivery of Isosorbide Dinitrate

2019 ◽  
Vol 25 (4) ◽  
pp. 311-318
Author(s):  
Marzieh Fathei ◽  
Mitra Alami-milani ◽  
Sara Salatin ◽  
Sharahm Sattari ◽  
Hassan Montazam ◽  
...  
Keyword(s):  
Drug Release ◽  
Isosorbide Dinitrate ◽  
Moisture Absorption ◽  
Ex Vivo ◽  
Hydroxypropyl Methylcellulose ◽  
Drug Bioavailability ◽  
Scanning Calorimetry ◽  
Surface Ph ◽  
Drug Content

Background: Isosorbide dinitrate (ISDN) is used for treating the angina attacks. In addition, oral ISDN is available in immediate and sustained release formulations and the bioavailability of ISDN is about 20-25% when taken orally. Further, the ISDN films are developed for sublingual drug delivery by improving drug bioavailability. The present study aimed to design and evaluate the physicochemical properties of the film formulation for sublingual delivery of ISDN. Methods: In the present study, sublingual films were prepared by the solvent casting technique using the hydroxypropyl methylcellulose (HPMC) polymers (i.e., 100, 150 and 200 mg) with a different drug to polymer ratios (i.e., 1:5, 1:7.5 and 1:10). Then, ISDN was evaluated for the film appearance, drug content, surface pH, mucoadhesion force, differential scanning calorimetry (DSC), in vitro drug release, and ex vivo permeability. Results: Based on the results, F3 formulation (1:10 ISDN to HPMC ratio) showed acceptable thickness (0.93 mm), weight (11.14 mg), surface pH (7.82), moisture absorption capacity (6.08%), elasticity (>200), mucoadhesion force (18.05 N/cm2), and drug content (6.22%). Furthermore, the results demonstrated that HPMC polymer improved the characteristics of the films, modified the bioadhesiveness, and finally, enhanced elasticity. However, DSC thermogram failed to show any crystalline drug substance in the films except for F1 (immediate release) and the endothermic peak of ISDN was absent in F2 and F3 films. Therefore, the drug which was entrapped into the film was in an amorphous or disturbed-crystalline phase of the molecular dispersion or dissolved in the melted polymer in the polymeric matrix. Moreover, the drug release from the films was faster compared to the tablet® (P<0.05). Conclusion: In general, the formulation of F1 was observed to be an appropriate candidate for developing the sublingual film for the remedial use.

Temperature Dependent Dynamic Mechanical Properties of Hydrogenated Nitrile Butadiene Rubber and the Effect of Peroxide Cross-linkers

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Blaž Likozar ◽  
Matjaž Krajnc
Keyword(s):  
Mechanical Properties ◽  
Cyano Group ◽  
Viscoelastic Behavior ◽  
Dynamic Mechanical Properties ◽  
Cross Linking ◽  
Butadiene Rubber ◽  
Scanning Calorimetry ◽  
Dynamic Mechanical ◽  
Nitrile Butadiene Rubber ◽  
The Cross

AbstractThe viscoelastic behavior of hydrogenated nitrile butadiene rubber (HNBR) was studied over a range of temperatures and shear frequencies. Dynamic mechanical properties were studied and modelled using the generalized Maxwell model and the Williams-Landel-Ferry equation. A fitting algorithm was developed to provide the best agreement between the experimental data and the model results. In addition to dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) was applied. The HNBR structure was characterized by X-ray diffraction (XRD). The developed model exhibited an excellent agreement with either isothermal or dynamic experiment data, yet only up to the rubbery plateau, after which a structure ordering occurred. This was explained by the cyano group secondary bonding and consequentially the cross-linking between HNBR chains. A molecular modeling simulation was made to confirm the cross-linking. The effect of peroxide cross-linking agents in a compound resembled the one usually observed in the filler formulated compounds.

scholarly journals Tailoring the Physico-Chemical Properties of Poly(xylitol-dicarboxylate-co-butylene dicarboxylate) Polyesters by Adjusting the Cross-Linking Time

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1493
Author(s):  
Marta Piątek-Hnat ◽  
Paulina Sładkiewicz ◽  
Kuba Bomba ◽  
Jakub Pęksiński ◽  
Agnieszka Kozłowska ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Sebacic Acid ◽  
Dicarboxylic Acids ◽  
Tensile Tests ◽  
Cross Linking ◽  
Resonance Spectroscopy ◽  
Aliphatic Chain ◽  
Scanning Calorimetry ◽  
The Cross

Determining the cross-linking time resulting in the best achievable properties in elastomers is a very important factor when considering their mass production. In this paper, five biodegradable polymers were synthesized—poly(xylitol-dicarboxylate-co-butylene dicarboxylate) polymers, based on xylitol obtained from renewable sources. Five different dicarboxylic acids with even numbers of carbon atoms in the aliphatic chain were used: succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanedioic acid. Samples were taken directly after polycondensation (prepolymer samples) and at different stages of the cross-linking process. Physiochemical properties were determined by a gel fraction test, differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), quasi-static tensile tests, nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR), and an in vitro biodegradation test. The best cross-linking time was determined to be 288h. Properties and degradation time can be tailored for specific applications by adjusting the dicarboxylic acid chain length.

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