Ultraviolet quantitative label-free detection of DNA amplification

A method of amplifying a nucleic acid molecule and quantifying amplification thereof, of a nucleic acid template with a polymerase chain reaction (PCR) or a loop-mediated isothermal amplification (LAMP), the method comprising:

• a) performing said PCR or said LAMP and during said PCR or said LAMP, irradiating a biological enzymatic reaction mixture in solution, for a period of time sufficient, with a heating activation light beam from a continuous wave laser, said biological enzymatic reaction mixture comprising said nucleic acid template, a polymerase enzyme and chemically modified nanoparticles comprising nanorods of metal, said heating activation light beam having a wavelength resonant with a surface plasmon of said chemically modified nanoparticles, which activates a plasmon resonance localized at a surface of said chemically modified nanoparticles, which causes a release of heat sufficient to heat a whole of said biological enzymatic reaction mixture and promote said PCR or said LAMP,
• b) irradiating said biological enzymatic reaction mixture with a monitoring ultraviolet (UV) light from an UV light source during an annealing step, an elongation step, or both, of said PCR or said LAMP, and
• c) measuring with a photodetector a transmission change in an UV light transmission from said biological enzymatic reaction mixture to quantify amplification of said nucleic acid template, wherein irradiating with said monitoring UV light from an UV light source is for a duration and at an UV light intensity sufficient for measuring said transmission change to measure a free nucleotide concentration to quantify amplification of said nucleic acid template in said biological enzymatic reaction mixture, while avoiding inhibition of amplification of said nucleic acid template.