Functionalized silica nanotube (FSNT) possessing a calix[4]arene moiety as a fluorescent receptor is fabricated by sol-gel reaction. The FSNT suspension in water selectively adsorbs 98% of Pb2+ over other metal ions (Li+, Na+, K+, Cs+, Mg2+, Ca2+, Ba2+, Zn2+, and Ag+) and shows quenched fluorescence emission in both pyrene monomer and excimer bands.