Search

We describe a competitive colorimetric assay that enables rapid and sensitive detection of galactose and reduced nicotinamide adenine dinucleotide (NADH) via colorimetric readouts and demonstrate its usefulness for monitoring NAD+-driven enzymatic reactions. We present a sensitive plasmonic sensing approach for assessing galactose concentration and the presence of NADH using galactose dehydrogenase-immobilized gold nanostars (AuNS-PVP-GalDH). The AuNS-PVP-GalDH assay remains turquoise blue in the absence of galactose and NADH; however, as galactose and NADH concentrations grow, the reaction well color changes to a characteristic red color in the presence of an alkaline environment and a metal ion catalyst (detection solution). As a result, when galactose is sensed in the presence of H 2 O 2 , the colored response of the AuNS-PVP-GalDH assay transforms from turquoise blue to light pink, and then to wine red in a concentration-dependent manner discernible to the human eye. This competitive AuNS-PVP-GalDH assay could be a viable analytical tool for rapid and convenient galactose quantification in resource-limited areas.

Plasmonic colorimetric sensors have emerged as powerful analytical tools in biochemistry due to their localized surface plasmon resonance extinction in the visible range. Here, we describe the feasibility of NAD(P)/NAD(P)H as redox agents in enzymatic plasmonic gold nanostar (AuNS) assays for galactose quantification using three model enzymes, GalDH, AR and GalOx, immobilized separately on polyvinylpyrrolidone-capped AuNS scaffolds. These highly specific, sensitive and selective bioassays induce the transformation of AuNS into quasi-spherical nanoparticles during the biorecognition of galactose in water and synthetic blood matrices. As a result, using our inexpensive and simple AuNS plasmon bioassays, the presence of galactose may be detected spectrophotometrically and by the naked eye., Competing Interests: We have no competing interests to declare., (© 2023 The Authors.)

The North-West University's Centre for Human Metabolomics (CHM) is in the process of establishing the first rare disease (RD) biobank in South Africa and Africa. The CHM Biobank's main focus is on the collection of samples and information for rare congenital disorders. Approximately 72% of all RDs have a genetic origin, of which 70% have an exclusive pediatric onset. The need for such a biobank was identified by the CHM diagnostic laboratory. Feedback toward this initiative was overwhelmingly positive at the first stakeholder meeting in August 2019. However, gaining support from the public sector and recruiting of participants have proven to be challenging. Problems experienced to date include lack of support from government and clinicians; lack of knowledge on RDs (patients and clinicians); public health care focus not directed toward RDs; patients not returning for follow-up visits; and unwillingness to participate due to fear of exploitation. The CHM Biobank's vision and goals are aligned to address a national and international research need: it will provide a valuable resource for scientists to improve what is known about these diseases; to better understand the natural history and pathophysiology; to optimize diagnostic methods; and to potentially develop treatments. The genetic variability of the South African population provides added value to the RD biobank. This review provides a brief overview of the literature on the challenges and benefits of an RD biobank and how this relates to low- and middle-income countries (LMIC) like South Africa. The aim of the review is to draw attention to the potential benefits of such an undertaking and to create awareness, at both local and global level, toward some of the unique collective considerations that an RD biobank in LMIC (also unique South African challenges) faces on an operational, collaborate, and sustainability level.