Novel methods to construct a multianalyte biosensing chip are described. A
method is two-step immobilization in which materials are not immobilized di
rectly but indirectly via small support materials. Biomaterials are immobil
ized on a certain support particle in the first step. The particles are pla
ced or stuck on a chip in the second step. The other method is random fluid
ic self-assembly of the microsupports for reducing the complication in the
second step on the chip. The combination of the methods enables us to immob
ilize various kinds of biomaterials densely on a chip. The ways to avoid po
ssible problems due to random distribution are discussed. Several examples
are also described. (C) 2000 Elsevier Science S.A. All rights reserved.