We present a method to characterize surface-chemical properties of gold nanocrystals. Spherical, 60 nm gold nanocrystals were immobilized on quartz substrates by a coupling agent and cleaned in a hydrogen plasma. The nanocrystals were then functionalized with alkanethiol self-assembled monolayers (SAM) of varying chain lengths by adsorption from the gas phase, and localized surface plasmon resonance (LSPR) spectroscopy was performed on the samples. Depending on the alkanethiol chain length, the adsorption of the SAM redshifted the LSPR to different extents, in accordance with Mie theory. SAM thickness differences below 1 nm could be easily resolved. Our results demonstrate that LSPR spectroscopy can be applied to characterize thin organic layers on dry supported gold particles with high sensitivity.
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http://dx.doi.org/10.1364/ol.33.000806 | DOI Listing |
BMC Vet Res
December 2024
Department of Parasitology, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt.
Strongylus vulgaris, a devastating parasitic nematode in equids, causes life-threatening verminous aneurysms that are challenging to diagnose early. This study pioneered integrating nanotechnology into an indirect enzyme-linked immunosorbent assay (i-ELISA) system to enhance the sensitivity and specificity for detecting S. vulgaris larval antigens in equine serum samples, with PCR confirmation of the species.
View Article and Find Full Text PDFMikrochim Acta
December 2024
State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, 214122, China.
A dual-signal aptamer-based assay utilizing colorimetric and fluorescence techniques was developed for the determination of zearalenone (ZEN). The CdTe quantum dots, serving as the fluorescent signal source, were surface-modified onto FeO@SiO and subsequently functionalized with the aptamer. The COF-Au was modified with complementary chain, which possessed peroxide (POD)-like enzyme properties, and could catalyze the peroxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to ox TMB, resulting in the generation of colorimetric signals.
View Article and Find Full Text PDFNanomaterials (Basel)
December 2024
College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
Chiral molecules are ubiquitous in nature and biological systems, where the unique optical and physical properties of chiral nanoparticles are closely linked to their shapes. Synthesizing chiral plasmonic nanomaterials with precise structures and tunable sizes is essential for exploring their applications. This study presents a method for growing three-dimensional chiral gold nanoflowers (Au NFs) derived from trisoctahedral (TOH) nanocrystals using D-cysteine and L-cysteine as chiral inducers.
View Article and Find Full Text PDFBiosensors (Basel)
December 2024
Department of Electronics, Electric, and Automatic Engineering, Rovira I Virgili University (URV), 43007 Tarragona, Spain.
Preeclampsia is a pregnancy-specific hypertensive syndrome recognized as the leading cause of maternal and fetal morbidity worldwide. Early diagnosis is crucial for mitigating its adverse effects, and recent investigations have identified endoglin as a potential biomarker for this purpose. Here, we present the development of a hybrid biosensor platform for the ultrasensitive detection of endoglin, aimed at enabling the early diagnosis of preeclampsia.
View Article and Find Full Text PDFBiosensors (Basel)
December 2024
International Research Center for Food and Health, Laboratory of Quality and Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture, Shanghai Engineering Research Center of Aquatic-Product Process & Preservation, College of Food Science and Technology, Shanghai Ocean University, Shanghai 201306, China.
Accurate methods for assessing food freshness through colorimetric pH response play a critical role in determining food spoilage and ensuring food quality standards. This study introduces a novel unlabeled DNA sequence, poly-dA, designed to exploit the colorimetric properties of both the single strand and the fold-back A-motif structure in conjunction with gold nanoparticles (AuNPs) under varying pH conditions. When exposed to storage temperatures of 4 °C and 25 °C, the color variations in the AuNP solution, influenced by pH level changes in mutton and sea bass samples' different storage periods, are easily discernible to the naked eye within a minute.
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