Sexual health products (e.g. condoms) are important for reducing the risk of contracting HIV and sexually transmitted infections (STIs) during all forms of intercourse including receptive anal intercourse (RAI). Their prophylactic properties rely on the proper use of the condom as well as the inclusion of a lubricant, without which condom mechanical failure and risk of infection are dramatically increased. An intrinsically lubricious surface coating would overcome the limitations of external lubrication, and could further reduce risk if anti-HIV drugs can be incorporated in to the coating. Hydrogels are excellent candidates for this given their biocompatibility, highly tunable physical and chemical properties, ability to be grafted as thin coatings to traditional condom materials such as latex and silicone, and ability to be loaded with and elude drugs. Hydrogel coatings on latex have recently been shown to reduce the friction 20-fold relative to the native latex surface. However, an in-depth understanding of hydrogel lubricating mechanisms and performance limits at physiological conditions is lacking. To systematically study the tribological properties of hydrogels, bulk hydrogels and their thin-coating counterparts were synthesized at different monomer and crosslinker densities to control the mesh size, water content, Young’s modulus, and frictional properties. Double network hydrogels were used due to their substantial mechanical durability. The frictional properties of the synthesized bulk hydrogels and hydrogel coatings were studied in aqueous environments at physiologically-relevant applied pressures, sliding speeds, and temperatures. A mini traction machine (MTM) was used for macroscale testing, providing additional insight into the mechanical durability of the hydrogels. Colloidal probe atomic force microscopy (AFM) was used to help further elucidate the underlying friction mechanisms. We observe low friction and wear, with a significant dependence of friction on sliding speed and hydrogel synthesis conditions. We will discuss how these characteristics impact the potential application use of hydrogels. Overall, the synthesis and characterization of the frictional properties of hydrogels aids the design of surface coatings with improved comfort and reliability, leading to a greater usage of sexual health products in HIV prevention.

Intrinsically lubricating hydrogel coatings for HIV prevention

2019 Fall National Meeting

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