Surface Modification of Cellulose Paper for Quantum Dot-based Sensing Applications

Cellulose paper specimens with and without surface modification were compared in order to study their physicochemical compatibility with quantum dots (QDs) for biochemical sensing applications. Silane and chitosan modification methods were applied. The distribution of QDs deposited on untreated paper and papers modified with silane and chitosan were investigated in order to understand the interaction between QDs and fibre. Modified papers were shown to significantly reduce the undesirable redistribution of QDs during paper drying. The retention ability and thermal resistance of QDs to the loss of fluorescence on modified papers were also studied for the purpose of determining the most suitable paper surface modification for developing QD-Paper-based analytical devices (QD-PADs). Furthermore, chitosan-modified paper was used to design QD-PADs to quantify glucose concentration in aqueous samples; the quenching effect of the enzymatic product on the fluorescent emission of QDs was used as the indicator system. The change of fluorescence of QDs was measured by a simple in-house constructed fluorescence imaging system. The detection limit of glucose was 5 mg/dL, which is comparable with other reported paper sensors for detection of glucose.