Selectivity Enhancement for Uric Acid Detection via In Situ Preparation of Blue Emissive Carbon Dots Entrapped in Chromium Metal–Organic Frameworks

Abstract

In the present work, for the first time, the in situ formation of blue emissive carbon dots (bCDs) and encapsulation into the pores of chromium-based metal–organic frameworks (Cr-MOFs) are described. The luminescent bCDs via in situ process are formed and entrapped inside the pores of Cr-MOFs to form a nanocomposite of bCDs@Cr-MOFs. The bCDs@Cr-MOFs showed a strong broad blue emission at 420 nm (excited at 310 nm), which corresponds to both, the ligand (2-aminoterephthalic acid) in the Cr-MOF and the entrapped bCDs. This is assigned for the entrapping of bCDs in the pores of the MOFs. Additionally, transmission electron microscopy (TEM) images showed two types of particles, 150 rod-like shapes for Cr-MOF and 5–10 nm spherical shapes assigned for the presence of bCDs. The bCDs alone (without Cr-MOF) showed no selectivity, and their emission was quenched by different biomolecules and ions, such as ascorbic acid, uric acid, Fe 3+ , Cu 2+ , and Hg 2+ . The selectivity of bCDs toward uric acid was increased dramatically when they were encapsulated in the Cr-MOF. The linear range for uric acid was 20–50 μM, and the LOD was measured as 1.3 μM. Spike recoveries for the detection of uric acid in serum samples were between 94 and 108%. The relative standard deviation (RSD, n = 3) at each concentration value was less than 2%. The results showed high ruggedness and robustness of the assay due to its high shelf-life stability of probe (four weeks), water stability, and long working pH range. Validation experiments showed that the established MOF-based sensing system is appropriate for uric acid detection in real samples.

Metallic nanostructure-based aptasensors for robust detection of proteins

“…116 The combination of aptamers with MOFs causes the formation of nanostructure with properties of both aptamer and MOFs. 117,118 MOFs with large surface areas permit an extensive range of ssDNA or RNA to adhere to the surface. Additionally, MOFs with adjustable pore diameters permit various nucleic acids to be immobilized on their surface.…”

Asterias forbesi-Inspired SERS Substrates for Wide-Range Detection of Uric Acid

“…To evaluate the selective UA detection capability of the fabricated AF-SERS substrate, signals from various metabolites were analyzed (Figure 4). Figure 4a presents the chemical formulations of target molecules used in the selectivity experiments, including UA (I), ascorbic acid (II), creatine (III), dopamine (IV), glucose (V), and L-cysteine (VI), which are representative metabolites [43][44][45][46]. UA was tested at a concentration of 800 µM, whereas the remaining substances were experimented with at a high concentration of 1 mM.…”

Environmentally sustainable synthesis of whey-based carbon dots for ferric ion detection in human serum and water samples: evaluating the greenness of the method

“… 8 The top-down method involves the utilization of carbon-rich materials or molecules as carbon sources, cutting larger carbon structures like graphite, carbon nanotubes, carbon soot, activated carbon, and graphite oxide into smaller CDs through techniques such as arc discharge, 9 laser ablation 10 and electrochemical methods. 11 On the other hand, bottom-up methods use organic molecules, such as glucose 12 and fructose 13 to react and form larger CDs by applying external energy like ultrasonication, 14 microwave pyrolysis, 15 heating, 16 hydrothermal, 17 and microwave irradiation. 18 Due to their unique properties, CDs have found applications in various fields, replacing toxic semiconductor quantum dots 19 made of heavy metals like cadmium 20 and lead.…”