The nearest MRT station to Biopolis is Buona Vista. This station is served by both the East West Line (EW21) and the Circle Line (CC22). Please refer to the MRT map here for connections.
Many buses serve the 2 bus stops at Buona Vista Station (heading south: 11369, heading north: 11361):
74, 91, 92, 95, 191, 196, 198, 200(A).
Please refer to gothere.sg for advice on public transport routes.
Taxis are readily available throughout Singapore, please ask the driver to go to Biopolis, near Buona Vista Station.