Nanoparticle modified QCM-based sensor for lipase activity determination

Abstract

A highly sensitive lipase activity sensor was developed and tested. It is based on the application of SiO 2 nanoparticle loaded olive oil as a lipase substrate, deposited on a QCM crystal. The heavier nanoparticles' release during the substrate enzymatic degradation causes a QCM frequency response enhancement proportional to the nanoparticle/substrate mass ratio.

AFM and MFM techniques for enzyme activity imaging and quantification

“…It is based on the real-time imaging, by atomic force microscopy (AFM) and magnetic force microscopy (MFM), of the degradation of a nanoparticles-loaded enzyme responsive layer, namely Fe 3 O 4nanoparticles-loaded gelatin. During the enzymatic gelatin degradation by trypsin as an example, the nanoparticles also leave the sensitive layer together with the substrate degradation products, as previously confirmed by quartz crystal microbalance (QCM)-based measurements [23,24].…”

“…The topological changes were attributed to the strong interaction between the enzyme and its substrate and the rapid dissolution of the obtained products. Such a degradation model was suggested in our previous works to explain the increase of the frequency response of the QCM-based sensors for enzyme activity evaluation [23,24]. Longer exposure time (30 min) resulted in layer flattening, followed by the almost complete ferrogel degradation within 60 min of exposure time, and roughness increase, as illustrated by Figure 2(c,d).…”

“…The Fe 3 O 4 -gelatin hydrosol was dried for 1 h at ambient temperature to obtain a ferrogel, which was used as a trypsin substrate and sample for AFM and MFM studies. The QCM-sensors for enzyme activity determination, described in our previous works were constructed applying a similar protocol [23,24]. The sample assembling scheme is presented in Figure 1.…”

Disease Detection with Molecular Biomarkers: From Chemistry of Body Fluids to Nature-Inspired Chemical Sensors

“…In one demonstration, a lipase substrate consisting of olive oil loaded with SiO 2 nanoparticles (gel) was deposited on the QCM. 274 After the gel was lipolyzed, the heavier nanoparticles were simultaneously released with their enzymatic degradation products, leaving the basal layer, resulting in an increase in the QCM frequency response. 274 An enzyme activity assay carrying a heavy nanoparticle matrix could achieve a 10-fold or even higher sensitivity compared to an unloaded matrix.…”

“…274 After the gel was lipolyzed, the heavier nanoparticles were simultaneously released with their enzymatic degradation products, leaving the basal layer, resulting in an increase in the QCM frequency response. 274 An enzyme activity assay carrying a heavy nanoparticle matrix could achieve a 10-fold or even higher sensitivity compared to an unloaded matrix. Lipase and trypsin are roughly identical in principle and are not recoverable.…”