Photothermal-Contrast Method Based on In Situ Gold Nanostructure Formation for Phenylalanine Detection in Human Blood

Abstract

An innovative approach based on photothermal contrast to enhance analytical sensitivity of enzymatic phenylalanine detection at a solid surface was demonstrated. Gold nanoparticles in situ produced by the reduced form of nicotinamide adenine dinucleotide, which is generated by an enzymatic reaction, exhibit an excellent photothermal effect upon green-light stimuli. The enzymatic reaction and the nanoparticles process formation were optically investigated. A sensing range of 10−1000 μM with a detection limit of 3.6 μM for phenylalanine detection were demonstrated. The testing with blood samples collected from phenylketonuria patients together with concurrent comparison through tandem mass spectrometry have confirmed the good analytical performances and the robustness and utility of the proposed photothermal-contrast approach for further integration on clinical devices.

Feasibility of NAD(P)/NAD(P)H as redox agents in enzymatic plasmonic gold nanostar assays for galactose quantification

“…In our bioassays, the AuNS operate as colorimetric and sensing signal amplifiers [77], avoiding the need for dyes, in contrast to the biosensor designs proposed by Messina et al [75] and Jafari et al [74]. Furthermore, our understanding of redox chemistry (equation (4.5)) confirms Maugeri et al's [76] findings that neo-formed NADH can react with Au 3+ to generate gold nanoparticles.…”

“…Open Sci. 10: 230825 in human blood using PDH, resulting in the creation of in situ gold nanostructures in the presence of neo-formed NADH and AuCl 4 − [76].…”

“…Messina et al [ 75 ] devised a highly sensitive colorimetric method for the enzymatic detection of Phe in the presence of neo-formed NADH using tris(bipyridine) ruthenium(II/III) mediator [ 75 ]. Furthermore, Maugeri et al [ 76 ] established a novel photothermal-contrast approach for Phe detection in human blood using PDH, resulting in the creation of in situ gold nanostructures in the presence of neo-formed NADH and AuCl 4 − [ 76 ].…”

“…Furthermore, our understanding of redox chemistry (equation (4.5)) confirms Maugeri et al . 's [ 76 ] findings that neo-formed NADH can react with Au 3+ to generate gold nanoparticles.…”

Quantitative Galactose Colorimetric Competitive Assay Based on Galactose Dehydrogenase and Plasmonic Gold Nanostars

“…The bromine intermediates (Br 3 − and Br 2 ) from cetyltrimethylammonium bromide (CTAB) and 5-bromosalicylic acid (5-BrSA) used to etch gold nanorods were reduced and consumed in the presence of NADH, inhibiting the etching rate and resulting in a slight blue shift of the LPB. Maugeri et al (2023) recently developed a unique photothermal-contrast method for detecting phenylalanine (Phe) in human blood using phenylalanine dehydrogenase (PDH), resulting in the formation of in situ AuNPs in the presence of neo-formed NADH and AuCl 4 − [83]. Jafari et al ( 2021) proposed a colorimetric-paper-based biosensor based on the PDH enzyme for highly sensitive and selective quantification of Phe, using neo-formed NADH, cationic dyes, and AuNPs as colorimetric mediators [84].…”