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ArticleSilver-Platinum Hollow Nanoparticles as Labels for Colorimetric Lateral Flow AssayJinfeng Zhou 1, Shikuan Shao 1, Zhiyuan Wei 1 and Xiaohu Xia 1,2,*1 Department of Chemistry, University of Central Florida, Orlando, FL 32816, USA2 NanoScience Technology Center, University of Central Florida, Orlando, FL 32816, USA* Correspondence: xiaohu.xia@ucf.eduReceived: 23 September 2024; Revised: 7 November 2024; Accepted: 12 November 2024; Published: 18 November 2024 Abstract: Colorimetric lateral flow assay (CLFA) has been a widely recognized point-of-care testing technology over the past few decades. Driven by the increasing demand in various biomedical applications, it is urgently needed to develop CLFAs with high sensitivities and low costs. In this work, we report a type of CLFA that relies on unique colorimetric labels—silver-platinum hollow nanoparticles (Ag-Pt HNPs). The Ag-Pt HNPs possess intrinsic enzyme-like catalytic activities, providing the Ag-Pt HNP-based CLFA with strong color signal and thus a high sensitivity. Meanwhile, the Ag-Pt HNPs have hollow interiors and are mainly composed of less expensive silver, making the Ag-Pt HNP-based CLFA cost-effective. Using prostate-specific antigen (PSA) as a model disease biomarker, the Ag-Pt HNP-based CLFA achieved a high sensitivity with a detection limit at the low picogram-per-milliliter level. Potential application of the CLFA in clinical diagnosis was demonstrated by detecting PSA from human serum samples. 

Abstract Limited access to food stores is often linked to higher health risks and lower community resilience. Socially vulnerable populations experience persistent disparities in equitable food store access. However, little research has been done to examine how people's access to food stores is affected by natural disasters. Previous studies mainly focus on examining potential access using the travel distance to the nearest food store, which often falls short of capturing the actual access of people. Therefore, to fill this gap, this paper incorporates human mobility patterns into the measure of actual access, leveraging large‐scale mobile phone data. Specifically, we propose a novel enhanced two‐step floating catchment area method with travel preferences (E2SFCA‐TP) to measure accessibility, which extends the traditional E2SFCA model by integrating actual human mobility behaviors. We then analyze people's actual access to grocery and convenience stores across both space and time under the devastating winter storm Uri in Harris County, Texas. Our results highlight the value of using human mobility patterns to better reflect people's actual access behaviors. The proposed E2SFCA‐TP measure is more capable of capturing mobility variations in people's access, compared with the traditional E2SFCA measure. This paper provides insights into food store access across space and time, which could aid decision making in resource allocation to enhance accessibility and mitigate the risk of food insecurity in underserved areas. 

Peroxidase mimics of nanoscale materials as alternatives to natural peroxidases have found widespread uses in biomedicine. Among various types of peroxidase mimics, platinum-group metal (PGM) nanocrystals have drawn considerable attention in recent years due to their superior properties. Particularly, PGM nanocrystals display high catalytic efficiencies, allow for facile surface modifications, and possess excellent stabilities. This feature article summarizes our recent work on development of PGM nanocrystals as peroxidase mimics and exploration of their applications in in vitro diagnostics. We begin with a brief introduction to controlled synthesis of PGM nanocrystals in solution phase. We then elaborate on a variety of physicochemical parameters that can be carefully tuned to optimize the peroxidase-like properties of PGM nanocrystals. Then, we highlight the applications of PGM nanocrystals in different in vitro diagnostic platforms. We conclude this article with personal perspectives on future research directions in this emerging field, where challenges and opportunities are remarked.