Metal deposition and shape reproduction at biological temperatures on cell-level samples.

The use of metal deposition has been limited to a limited number of applicable samples due to the increased temperature caused by accelerated electron impact on the substrate surface. The surfaces of various biological samples have a nanoscale structure with specific properties, which have been simulated in numerous studies. However, no examples of nano/microscale reproductions of biological surface features have used moulds. In this study, a mould that imitates the surface shape of a cellular-level biological material was fabricated, for the first time, and the shape was successfully reproduced using the mould. Al thin films were deposited on bovine sperm using magnetron sputtering without thermal denaturation with a cathode operating at a biological temperature. It is difficult to deposit films used as metal coatings on pre-treated biological materials at temperatures below 40 °C during evaporation. The Al thin film was peeled off and used as a mould to reproduce the shape of the sperm with high accuracy using a polymer. The results of this study represent a major innovation in reproducible biomimetic moulding technology, demonstrating biological temperature sputtering. We expect our non-destructive metal deposition and metal nano-moulding methods for biological samples to be the basis for the effective utilization of various biological structures.