Toshikazu Tomioka

Inactivation of Enveloped Viruses by a Silver-Thiosulfate Complex

AmenitopTM was developed by Matsushita Electric Industrial Co., Ltd. It is an inorganic material originally developed to prevent bacterial contamination on the surface of appliances such as telephone and facsimile machines, and consists of silica gel micmspheres containing silverthiosulfate complex (AT-l). It has a coating layer of tetraethoxysilanet that enables gradual release of AT-1 on the surface. AT-1 showed bactericidal effect on various kinds of bacteria such as E. co S. aumus, methicillin resistant S. aumus (MRSA). So, we examined antiviral effect of AT-1 on several kinds of viruses such as human immunodeficiency virus-1 (HIV-1, JMH-1), herpes simplex virus type-2 (HSV-2, G strain), measles virus (MV, Nagahata strain) and polio virus type1 (PV, Sabin vaccine type 1). AT-1 was extracted into phosphate buffered saline (PBS) from AmenitopTM at 37 C.for 30 min to obtain pure AT-I. The extracted AT-1 was stored at -80 C until use. HIV-1 was propagated in MT-4 cells. HSV-2, MV and PV were propagated in Veto cells. Stock viruses were prepared from the culture supematant fluids by low speed centrifugation and stored at -80 C until use. An aliquot of 500 I1 of the stock virus and AT-1 was mixed and incubated at 37 C, 22 C or 4 C for a given time. AT-1 was removed from the mixture by centrifugation using Centrisart (Sartorius Co. Ltd., cut off M.W. 20000) after the incubation. Then, the mixture was supplemented with 1 ml of PBS. Virus infectivity was measured using microplates by observing cytopathic effect. AT-1 reduced infectivity of HIV-1103 TCID5o/ml in 30 min at 37 C. The inactivating effect of AT-1 on HIV-1 was temperature-dependent and it failed to inactivate HIV-1 at 4 C. Further, we examined the inhibiting effect of AT-1 on HIV-1 multiplication. Twelve nM of AT-1 in the culture medium inhibited multiplication of HIV-1 during 4 to 7 days culture after infection at multiplicity of infection 0.001 without any cytotoxicity. Likewise, AT-1 inactivated MV104 TCID5o/ml at 37 C in 30 min. Temperature dependency of the inactivating effect of AT-1 was the same as in the case of HIV-1 and it failed to inactivate MV at 4 C even after 3 hours incubation. Inactivation of HSV-2 and PV with AT-1 was similarly examined. AT-1 inactivated HSV-2 106 TCID5o/mI. However, PV did not show any reduction in infectivity. The results suggest membrane-destroying effect of AT-I.

Effect of Silica Gel Carriers on Thermal Stability of the Anti-microbial Material with Thiosulfato Silver Complex.

シリカゲル担体にチオスルファト銀錯体を担持させて抗菌剤を調製し,担持効果が抗菌剤の熱安定性に与える影響を研究した。担体の比表面積の増加あるいは細孔容積の減少に伴い抗菌剤を含む成形樹脂の色調変化に抑制効果が認められた。熱分析,樹脂加工時の熱による樹脂色調の測定結果から,シリカゲル担体に熱処理を施すことにより,抗菌剤の熱安定性向上が認められた。抗菌剤添加成形樹脂の色調変化は,樹脂成形の加熱加工に伴う担体シリカゲルから遊離した吸着水分によるチオスルファト銀錯体の分解,酸化と考えられる,シリカゲル担体の熱処理により,担体に吸着保持される水分量を低減させ,その結果,樹脂加熱加工時に遊離する水分量を低減させることで,色調変化を抑制したものと考えられる。

Release Control of Anti-microbial Materials Coated with Hydrolyzed Tetraethoxysilane.

シリカゲル担体にチオスルファト銀錯体を担持させ,テトラエトキシシラン加水分解物によりその表面を被覆した抗菌剤を調製した。表面被覆処理により,抗菌成分の徐放性向上が認められた。抗菌成分は,抗菌剤含有樹脂中で周囲樹脂中に浸出することを,表面分析により確認した。さらに,樹脂表面が水分と接触することで水分中に浸出する。抗菌剤表面を被覆する TEOS 処理量の増加とともに,抗菌成分浸出速度が低下することを確認した。これらのことから,抗菌剤表面を TEOS 加水分解物で被覆することで抗菌成分の徐放性向上に対する効果が認められた。

Thermal Stability of Antimicrobial Materials Coated with Hydrolyzed Tetraethoxysilane

Antimicrobial materials were synthesized with a silver thiosulfate complex on silica gel. Their thermal stability was improved by coating the surface with hydrolyzed tetraethoxysilane. The chemical interaction was presumed present on silica gel with coated materials based on the improvement with the increasing amount of TEOS used and the absence of improvement with the coating by less interactive materials.