title: Label-Free real-time quantification of enzyme levels by interferometric spectroscopy combined with gelatin-modified nanoporous anodic alumina photonic films.
abstract: Herein, we present an interferometric sensor based on the combination of chemically functionalized nanoporous anodic alumina photonic films (NAA-PFs) and reflectometric interference spectroscopy (RIfS) aimed to detect trace levels of enzymes by selective digestion of gelatin. The fabrication and sensing performance of the proposed sensor were characterized in real-time by estimating the changes in effective optical thickness (i.e., sensing principle) of gelatin-modified NAA-PFs (i.e., sensing element) during enzymatic digestion. The working range (WR), sensitivity (S), low limit of detection (LLoD), and linearity (R(2)) of this enzymatic sensor were established by a series of experiments with different concentrations of gelatin (i.e., specific chemical sensing element) and trypsin (i.e., analyte), a model protease enzyme with relevant implications as a biomarker in the diagnosis of several diseases. The chemical selectivity of the sensor was demonstrated by comparison of gelatin digestion by other nonspecific enzyme models such as chymotrypsin and horseradish peroxidase. Furthermore, the role of the chemical sensing element (i.e., gelatin) was assessed by using hemoglobin instead of gelatin. Finally, we demonstrated that this sensor can be readily used to establish the kinetic parameters of enzymatic reactions. The obtained results revealed that the presented sensor has a promising potential to be used as a point-of-care system for fast detection of gastrointestinal diseases at early stages.
authors.affiliation: School of Chemical Engineering, The University of Adelaide , Engineering North Building, 5005 Adelaide, South Australia, Australia.
authors.forename: Mahdieh
authors.initials: M
authors.lastname: Nemati
authors.affiliation: School of Chemical Engineering, The University of Adelaide , Engineering North Building, 5005 Adelaide, South Australia, Australia.
authors.forename: Abel
authors.initials: A
authors.lastname: Santos
authors.affiliation: School of Chemical Engineering, The University of Adelaide , Engineering North Building, 5005 Adelaide, South Australia, Australia.
authors.forename: Tushar
authors.initials: T
authors.lastname: Kumeria
authors.affiliation: School of Chemical Engineering, The University of Adelaide , Engineering North Building, 5005 Adelaide, South Australia, Australia.
authors.forename: Dusan
authors.initials: D
authors.lastname: Losic
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D004566:Electrodes; D005780:Gelatin / Q000737:chemistry*; D007368:Interferometry; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D017785:Photons; D016062:Porosity; D013499:Surface Properties; D013997:Time Factors; D014357:Trypsin / Q000032:analysis* / Q000378:metabolism
chemical_list: D005780:Gelatin; D014357:Trypsin; D000537:Aluminum Oxide