VIRUCIDAL ACTIVITY OF EPOXY RESINS

BACKGROUND AND AIM Sanitary surfaces play an important role in the transmission of nosocomial pathogens. Such evidence justifies the growing interest in identifying new materials to prevent and mitigate infectious risk. The objective of our project is to develop innovative nanostructured materials with antimicrobial properties to be used as collective protection measures in health settings. Here, we present the results of a study on the virucidal activity of 5 samples of 3 different commercial epoxy resins. MATERIALS AND METHODS Three commercial epoxy resins have been used as polymer precursors: (1) Diglycidyl ether of bisphenol A epoxide (DGEBA, Elan Tech EC157), (ii) EPIKOTETM Resin MGS®; and (3) MC152. The epoxy resins have been prepared according to the resin/curing agent amounts indicated by the suppliers; resins 1 and 2 were also prepared with 10% w/w excess of curing agent (1b) and (2b). The virucide activity was tested against Herpes Simplex Virus type-1 (HSV-1), AdenoVirus type-5 (AdV5) and Human CoronaVirus OC43 (HCoV-OC43). Protocol 1 had the aim to verify a virucide activity of resins by contact, while protocol 2 was set to assay whether the resins release virucidal molecule(s) in the medium. Protocol 1: the resin coupons were soaked in 2 mL of a viral suspension of known concentration, vortexed for 30 seconds and then incubated for 1h and 24h. Protocol 2: the coupons were soaked in 1 mL of maintenance medium for 24h with continuous shaking. After 24 hours, the coupon was discarded and the supernatant incubated with the viral suspensions for 1h and 24h. In both cases, at the end of the incubation time the residual viral load was quantified by end-point titration. RESULTS The sample 2b showed a remarkable inactivating activity against HSV-1 and, to a less extent, against HCoV-OC43, by both contact and release, although the inhibition is greater by release. In the case of the studies by contact the viral titre reduction was 0.7 Log after 1h and 3.5 Log after 24h and 1.7 Log and 3.4 Log in the release studies for HSV-1; for HCoV-OC43, a significant reduction was obtained only with 24h incubation, both by contact (1 Log reduction) and release (2.7 Log). No anti AdV activity was observed. The sample 2a showed a higher anti HSV-1 activity, but no activity against HCoV and AdV. The other resins did not display any significant antiviral activity. DISCUSSION AND CONCLUSIONS These commercial resins with intrinsic antimicrobial properties can constitute an ideal support in which to incorporate antimicrobial nanomaterials for the creation of high tactility objects (handles, furnishing elements, etc.) to be applied in the healthcare sector for the prevention of HAIs. Currently, we are testing the resins 2 with nanostructured clays included.