Study On Preparation And Biocompatibility Of Wet-skid Resistance Rubber Band For Hemorrhoid Ligation

Hemorrhoid is a common clinical disease, which threats people’s health seriously. Rubber band ligation is the preferred non-surgical treatment for hemorrhoids. The development of ligation always focus on the innovation of the instrument, while materials of rubber band have rarely been mentioned. Natural rubber(NR) is the common medical elastomer, which has been used in biofilms, catheters, gloves, pacifiers and various kinds of dental equipment for decades. However, the application of NR in ligation is restricted seriously by many deficiencies, which including the poor biocompatibility that leads to infection and inflammation easily; the low Wet-skid resistance(WSR) which leads to instability of ligation so that rubber ring may shed; the attachment of proteins and cells which provide the breeding basis for bacteria to aggravate the patients’ suffering. Focused on the deficiencies mentioned above, we aimed to develop a new ligation based on NR, which possesses excellent mechanical strength, WSR property and biocompatibility.First, medical grade processing aids, including sulfuration aid, antioxidation aid, decentralization aid and glycerol-gelatin were used to improve the properties of NR strengthen by fumed silica. Then the mechanical property, aging resistance and hydrophilicity /hydrophobicity of NR were characterized by electronic tensile tester, scanning electron microscope(SEM), atomic force microscope(AFM), constant temperature and humidity tester, contact angle instrument. In this part, we obtained a rubber band ligation based on NR with excellent comprehensive properties, whose ensile strength was 30 MPa, elongation at break was 1003%, contact angle was 73o, permanent deformation was 5% and hardness was 60 A, which definitely satisfy the using demands of the rubber band ligation device.Then, the WSR property of rubber band ligation was characterized by stress, stress relaxation, surface roughness, micro hardness and dynamic viscoelasticity. Compared to the NR improved by carbon black, precipitated silica and fumed silica, the stretching stresses of NR improved by gelatin-glycerin and fumed silica at 100%, 300% and 500% were improved obviously while the stress relaxation were not obviously. Besides, the NR improved by gelatin-glycerin and fumed silica has greater micro surface roughness and micro hardness, which could pierce the water film when contacted with moist surface and then increase the friction. The results of dynamic viscoelasticity indicated that the dynamic viscoelasticity of NR improved by gelatin-glycerin and fumed silica had higher internal friction angle to enhance adhesive friction and hysteretic friction.At last, the biocompatibility of rubber band ligation was characterized by cell adhesion and proliferation, protein adhesion and preliminary animal experiments. The results showed that no toxic substances were released to inhibit the growth of cells during 1-7days, and at the same time, proteins and cells didn’t adhere to the material surface, which proved that the rubber band ligation would not cause tissue adhesion and aggravation of suffering. Preliminary experiments on rats revealed that the rubber ring ligation kept firm without peeling when ligated surgically in rats; the postoperative activity of rats were normal; tissue blood was blocked completely; no wound infection and inflammation were observed and wound healed quickly.