Silicon Nanowires-Based Fluorescence Sensor for Cu(II)

Abstract

Si nanowires (SiNWs) were covalently modified by fluorescence ligand, N-(quinoline-8-yl)-2-(3-triethoxysilyl-propylamino)-acetamide (QlOEt) and finally formed an optical sensor to realize a highly sensitive and selective detection for Cu(II). The QlOEt-modified SiNWs sensor has sensitivity for Cu(II) down to 10(-8) M, which is more sensitive than QlOEt alone. Metal ions interferences have no observable effect on the sensitivity and selectivity of QlOEt-modified SiNWs sensor. The SiNWs-based fluorescence sensor is reversible by addition of acid to replace Cu(II). The sensing mechanisms of QlOEt-modified SiNWs to Cu(II) and the rationale for the increase in sensitivity and selectivity of QlOEt-modified SiNWs over QlOEt on Cu(II) are discussed. The current sensor structure may be extendable to other chemo- and biosensors, and even to nanosensors for direct detection of specific materials in intracellular environment.

R6G/8-AQ co-functionalized Fe3O4@SiO2 nanoparticles for fluorescence detection of trace Hg2+ and Zn2+ in aqueous solution

“…Recently, N-(quinolin-8-yl)-2-(3-(triethoxysilyl-propylamino)-acetamide (QIOEt), a substance which can chelate Zn 2+ , has bee n synthesized and coupled with silica-NPs [28], ordered mesoporous silica material (MCM-41) [29] and silicon nanowires [30], and they all show remarkably improved sensitivity to Zn 2+ than QIOEt alone. Moreover, to ensure the recovery of the sensor materials, magnetic NPs were used.…”

“…However, with addition of Zn 2+ , a remarkable enhancement in the fluorescence intensity at 480 nm was observed, revealing that the R6G/8-AQ co-functionalized Fe 3 O 4 @SiO 2 NPs has good selectivity to Zn 2+ . It can be explained that the intra-molecular H-binding in 8-AQ leads to the proton transfer from the amine to the heterocyclic nitrogen atom in the excited-state [30]. This excited-state proton-transfer coupled with a photoinduced electron transfer from the 8-amino residue to the quinoline nitrogen atom would strongly suppress the fluorescence of 8-AQ derivatives [30].…”

“…It can be explained that the intra-molecular H-binding in 8-AQ leads to the proton transfer from the amine to the heterocyclic nitrogen atom in the excited-state [30]. This excited-state proton-transfer coupled with a photoinduced electron transfer from the 8-amino residue to the quinoline nitrogen atom would strongly suppress the fluorescence of 8-AQ derivatives [30]. However, Zn 2+ could interrupt the excited state proton transfer in 8-AQ derivatives, thus fluorescence enhancement was observed with the addition of Zn 2+ .…”

Silicon-Based Platform for Biosensing Applications

“…Based on the observed changes of fluorescence, low-concentration (10-8 M) Cu 2+ could be readily detected. In addition to the high sensitivity, this kind of fluorescent sensor featured excellent specificity, allowing specific detection of Cu 2+ in spite of existence of interfering metal ions [112]. More recently, He et al employed AuNPs-coated SiNWs as novel quenchers with high fluorescence quenching efficiency ([90 %) to construct high-performance multicolor molecular beacons (MBs).…”

The Composites of Cationic Polyelectrolyte and Glutathione‐capped Quantum Dots for Selective Fluorescence Detection of Cu2+

“…12 Fluorescence quenching based on the formation of Cu 2+ -ligand complexes is an alternative approach for simple and rapid detection of Cu 2+ in an aqueous solution. [14][15][16] In general, the fluorescent sensor consisted of a fluorophore and a complexing unit linked together through an appropriate spacer. Besides, fluorescence resonance energy transfer from the fluorophore to the quencher has been applied to sensing of Cu 2+ with high sensitivity and selectivity.…”