ABSTRACT
PURPOSE: To create a non-cytotoxic, spontaneously curing tissue adhesive that is strongly bonding and persistent enough that 1-2 µL is capable of sealing a clear corneal incision throughout the first five days of healing. METHODS: A novel prototype delivery device capable of delivering 1-2 µL of a two-component adhesive delivered aqueous solutions of dextran aldehyde and star PEG amine, which mixed by diffusion and crosslinked to form an adhesive hydrogel. Adhesive hydrogels were tested for rates of degradation in phosphate-buffered saline, leak pressures when used to seal clear corneal incisions in enucleated rabbit eyes, and in vitro cytotoxicity when placed in contact with NIH3T3 fibroblast cells. Two formulations were used in vivo to seal clear corneal incisions in New Zealand White rabbits. Wound integrity after 1, 3, 5 and 7 days of healing was assessed by measuring the leak pressures of enucleated eyes. RESULTS: Tissue adhesives formed by combining aqueous solutions of dextran aldehyde (MW 10,000, 50% oxidized) and an 8-arm star poly(ethylene glycol) (MW 10,000) having two primary amine groups at the end of each arm gave mean leak pressures as high as 141 ± 35 mm Hg and exhibited no in vitro cytotoxicity. When 1-2 µL was used in vivo to seal clear corneal incisions in New Zealand White rabbits, the adhesive maintained an eye leak pressure of at least 120 mm Hg and remained visibly present at the wound site for 5 days. CONCLUSIONS: The combination of an 8-arm star poly(ethylene glycol), MW 10,000, having two primary amine groups at the end of each arm and dextran aldehyde (MW 10,000, 50% oxidized) forms a tissue adhesive that cures spontaneously, is non-cytotoxic, and is strongly bonding and persistent enough that 1-2 µL is capable of sealing a clear corneal incision through the first 5 days of healing.
Subject(s)
Cornea/surgery , Dextrans/administration & dosage , Polyethylene Glycols/administration & dosage , Surgical Wound Dehiscence/therapy , Tissue Adhesives/administration & dosage , Wound Healing/drug effects , Administration, Topical , Aldehydes , Animals , Cornea/drug effects , Cornea/pathology , Disease Models, Animal , Follow-Up Studies , RabbitsABSTRACT
Calcium D-glucarate was converted into D-glucaro-1,4:6,3-dilactone on 32-g, 1-kg, and 22-kg scale, using azeotropic distillation with methyl isobutyl ketone to drive the dehydration. The crystalline product was > or = 99.5% pure by GC and NMR, and overall yield was as high as 72%.
Subject(s)
Glucaric Acid/analogs & derivatives , Lactones/chemical synthesis , Crystallization , Glucaric Acid/chemical synthesis , Magnetic Resonance SpectroscopyABSTRACT
Swellable PEG amine/dextran aldehyde composite materials are emerging as a controlled, biocompatible tissue adhesive. We explain how preservation of natural tissue amines provides biocompatibility for PEG/dextran that exceeds the stringent, destructive cyanide-based chemistry of cyanoacrylates, and adhere far better than fibrin glue. Strategic variations of material composition allow for the improvement of biocompatibility and adhesion strength. Material variations can be tailored to match the needs of specific tissue beds for an array of clinical applications. PEG/dextran cohesive properties are most responsive to variations in the PEG component (number of arms and solid content), while tissue/material adhesion strength is primarily determined by the number of aldehydes in the dextran.
Subject(s)
Hydrogels/chemistry , Adhesiveness , Biocompatible Materials/chemistry , Dextrans/chemistry , Materials Testing , Polyethylene Glycols/chemistry , Structure-Activity Relationship , Tissue AdhesivesABSTRACT
PURPOSE: To investigate the ability of a novel polysaccharide-based tissue adhesive to seal corneal incisions, and to determine the effect of the tissue adhesive on corneal endothelial cells. METHODS: A polysaccharide-based tissue adhesive composed of dextran aldehyde and star PEG amines was applied to a 5-mm corneal incision on an enucleated rabbit eye, and the leak pressure of the eye was measured. The tissue adhesive was additionally incubated in direct contact with bovine corneal endothelial cells to evaluate cytotoxicity. RESULTS: The polysaccharide-based tissue adhesive was successful in sealing corneal incisions to pressures of > 10 psi (500 mmHg). The tissue adhesive was non-cytotoxic to bovine corneal endothelial cells. CONCLUSIONS: Polysaccharide-based tissue adhesives are efficacious in sealing corneal wounds and are non-cytotoxic to corneal endothelial cells. Such adhesives represent a promising new technology for ophthalmic surgery.
Subject(s)
Cornea/surgery , Polysaccharides/pharmacology , Surgical Wound Dehiscence/prevention & control , Tissue Adhesives/pharmacology , Wound Healing/drug effects , Animals , Cattle , Cell Culture Techniques , Cell Survival/drug effects , Dextrans/chemistry , Endothelium, Corneal/drug effects , Intraocular Pressure , Polyethylene Glycols/chemistry , Polysaccharides/chemistry , Polysaccharides/toxicity , Rabbits , Tissue Adhesives/chemistry , Tissue Adhesives/toxicityABSTRACT
The effects of polysaccharide-based tissue adhesives on cell survival and inflammatory cell activation were determined using in vitro mouse cell cultures. Cytotoxicity of tissue adhesives was evaluated by placing adhesives in direct contact with 3T3 fibroblast cells. Polysaccharide-based tissue adhesives composed of dextran aldehyde and star PEG amine were non-cytotoxic to fibroblasts; in contrast, a commercial adhesive composed of 2-octyl cyanoacrylate was highly cytotoxic to fibroblasts. The inflammatory potential of tissue adhesives was evaluated by exposing J774 macrophage cells to adhesives, and measuring TNF-alpha release from macrophages. Polysaccharide-based tissue adhesives did not elicit inflammatory TNF-alpha release from macrophages. These results suggest that polysaccharide-based tissue adhesives are non-cytotoxic and non-inflammatory; the results are therefore significant in the design of in vitro cell culture systems to study biomaterials.
Subject(s)
Fibroblasts/drug effects , Macrophages/drug effects , Tissue Adhesives/adverse effects , Animals , Biocompatible Materials/adverse effects , Cell Line , Cell Survival/drug effects , Dextrans/adverse effects , Macrophage Activation/drug effects , Mice , Polyethylenes/adverse effects , Polyethylenes/chemistry , Tissue Adhesives/chemistryABSTRACT
The mechanism of hydrolysis of isopropenyl alpha- and beta-glucopyranosides (1 and 2, respectively) has been studied by temperature-dependent reaction kinetics, stereochemical analysis of products by (1)H NMR, solvent (18)O- and (2)H-labeling experiments, kinetic solvent deuterium isotope effects, and alpha-values for general acid catalysis. Compounds 1 and 2 are the first vinyl acetals to be shown to undergo hydrolysis exclusively by cleavage of the vinyl ether and not the acetal C-O bond. While both glucopyranosides undergo irreversible, rate-limiting C-protonation, 1 hydrolyzes approximately four times faster than 2 and has an enthalpy of activation that is 5.8 kcal mol(-)(1) lower than that of 2, suggesting that 1 is kinetically more basic than 2. Spectroscopic evidence indicates that conjugation of the glycosidic oxygen with the alkenyl double bond is greater in 1 than in 2, probably because of steric or conformational constraints.
ABSTRACT
Yeast hexokinase (EC 2.7.1.1) catalyzes the phosphorylation of pyranose and furanose analogs of glucose at 0.01-125% of the rate of glucose. The enzyme is highly tolerant of structural changes at C-2 and C-3 of glucopyranose and less tolerant of changes at C-1 and C-4. Preparative phosphorylations were performed on compounds having 0.01-100% of the activity of glucose, using phosphoenolpyruvate and pyruvate kinase to regenerate ATP. The effects of inhibition of hexokinase by phosphoenolpyruvate and acetyl phosphate on cofactor regeneration are discussed.
