Nucleic acids can be amplified and detected using an element which has a sealable support on which is disposed a nucleic acid reagent composition. The composition is a mixture of a nucleic acid reagent composed of polymeric particles to which an oligonucleotide is covalently attached. The particles are prepared from a first polymer having a glass transition temperature of at least about 70.degree. C. and have an average diameter of from about 0.1 to about 3 micrometers. The reagent is adhered to the support using a water insoluble adhesive comprising a second polymer which has a glass transition temperature which is at least about 30.degree. C. less than the glass transition temperature of the first polymer. The adhesive is present in the composition at from about 1 to about 20 dry weight percent. The method provides high sensitivity and low background in the assay of nucleic acids, preferably using polymerase chain reaction.