Methods and systems of quantifying a target material in solution include detection of a size change of a hybridized nucleic acid complex, without the use of nanobeads. In particular, the examples include providing a plurality of nucleic acid fragments and a species-specific oligonucleotide tags, measuring the size of the nucleic acid fragments and/or oligonucleotides to predetermine a standard distribution of the solution(s), introducing the oligonucleotides in a solution containing nucleic acid target materials and/or non-target materials, and hybridizing the oligonucleotides with the species-specific target material if present in the solution. The size of the nucleic acid complexes in solution are then measured after hybridization, and the presence or non-presence of the species-specific target material is detected and/or quantified by comparing the measured size of the nucleic acid complexes after hybridization to the standard distribution.