LAUSR

Photonic crystals (PhCs) possess outstanding optical properties that can be exploited for chemical sensing. We utilized a three-dimensional close-packed PhC structure made of functionalized silica nanoparticles. They consist of alternating high and low refractive index regions and have optical properties, such as photonic band structures, that are very sensitive to the change of physical structures. This study used 2,4,6-trinitrotoluene (TNT) to illustrate a detection method based on the transmissive photonic band edge shift (TPBES) due to the binding of TNT with amine anchored on particle surfaces to form Meisenheimer (amine-TNT) complexes. PhCs are exceptionally sensitive to a small change in refractive index caused by surface modification. As a result, they are suitable for sensing specific reactions between an amine and TNT. This method achieved a wide detection range of TNT concentrations from 10–12 to 10–4 M. 2,4-Dinitrotoluene (DNT) and toluene were used as a control and blank, respectively. Becaus...