This work focuses on the development of biological analysis tools using zinc selenide quantum dots (ZnSe QDs). Conjugating water-dispersible ZnSe QDs with oligonucleotides of increasing length was found to increase their photoluminescence (PL) intensity monotonically up to a certain length. Varying the sequence of the oligonucleotide without changing its length does not produce any measurable PL intensity change. The stability of QDs in water was significantly enhanced after conjugation with oligonucleotides. DNA hybridization was studied using QDs functionalized with complementary oligonucleotides. Hybridization of complementary QD-oligonucleotide complexes causes significant PL intensity amplification and a measurable red shift of the PL emission peak. The QD-oligo complexes are very stable in water under ambient dark conditions. Finally, a size-dependent optimal dilution of free QDs was discovered, corresponding to an optimal inter-QD-spacing that results in the highest PL emission intensity from as-prepared QD dispersions. Ongoing experiments in our laboratory aim to develop multiplexed DNA probes and immunoassays by employing luminescent QDs emitting at different wavelengths.