Table 4: OP biosensors based on sol-gel immobilized AChE.

Mode of detectionTransducerEnzyme immobilization methodMinimum detection limitLinearity Substrate/enzyme inhibitorTime of incubation
(min)
Storage stability
(days)
Reference

OpticalSol-gel/TMOSEncapsulation0.94 μM
42.19 μM
3.17–31.48
14.89–998.40 μM
Naled, Mecarbam530[65]

OpticalSol-gel/GlassEncapsulation0.098 μM0.098–0.55 μMParaoxon30NR[66]

AmperometricSilica sol-gel/SPEEncapsulation0.024, 0.015, and 0.012 μM0.01–0.001 μMParaoxon, dichlorvos, and chlorpyrifos-ethyl oxon206[67]

AmperometricTMOS sol-gel/SPEEncapsulation1.0 × 10−3μM1.0 and 3.0 × 10−3μMDichlorvos15NR[68]

AmperometricTEOS sol-gel/GCEEncapsulation0.008 μM0.008–0.81 μMOxydemeton methyl2021[69]

OpticalChromo-ionophore/Sol-gelEncapsulation2.26 μM2.26–31.67 μMDichlorvos 15NR[70]

AmperometricAl2O3 sol-gel matrix SPEAdsorption0.01 μM0.1–80 μMDichlorvos155[71]

AmperometricSol-gel matrix on TCNQ modified SPEEntrapment1 × 10−2, 
8 × 10−4, and 2 × 10−2μM
NRCarbaryl, carbofuran, and pirimicard2045[72]

ElectrochemicalAuNPs-SiSG/GCEHydrogen bonds0.44 μMNRMonocrotophos1030[73]

AmperometricAlumina/sol-gel/sonogel composite/Carbon electrodeEncapsulation2.5 × 10−4μM0.5 μMChlorpyriphos-ethyl oxon1050[74]

OpticalBromothymol blue/sol-gelEncapsulation0.11 μM0.14–5.70 μMChlorpyrifos810[75]

AmperometricZinc oxide/sol-gel/SPE0.127 μM0.127–5.010 μMParaoxon 1090[76]

AmperometricSilica/sol-gel/Carbon electrodeEncapsulation3.0 × 10−4 and 0.47 μM3.7 × 10−4–1.8 × 10−3 and 0.27–4.09 μMMethyl parathion and acephate20 and 430[77]

Cyclic VoltametrySol-gel/carbon electrodeEntrapment0.04 ppb for parathion, 47 ppb for monocrotophos0.1–1.0 ppbParathion and monocrotophos10NR[78]

Note: NR: not reported.