A femtosecond Bessel laser for preparing a nontoxic slippery liquid-infused porous surface (SLIPS) for improving the hemocompatibility of NiTi alloys

A slippery liquid-infused porous surface (SLIPS) is able to improve the hemocompatibility of implantable medical materials, which have saved countless lives. However, the preparation of a SLIPS on an implantable metal substrate (especially NiTi alloys) is still a substantial challenge because of the great difficulty of forming abundant porous microstructures on hard metals. In this paper, a novel strategy to prepare a SLIPS on a NiTi alloy substrate is reported. We used the laser pulse train of a femtosecond Bessel laser rather than the common Gaussian beam to directly create deep porous microstructures on the surface of the implantable NiTi alloy. Based on the laser-induced porous microstructure, the SLIPS was obtained by lowering the surface energy and infusing the lubricant liquid into the pores. The as-prepared SLIPS very effectively repelled water and blood. The hemocompatibility of the NiTi alloy was greatly improved after the formation of the SLIPS by the femtosecond Bessel laser processing. It was demonstrated that the SLIPS gives the NiTi alloy a remarkable anticoagulation property, very low hemolysis rate, and antibacterial property. We believe that the laser-induced SLIPS will accelerate the broad application of metal implants in the medical field in a healthier and safer way.