Tuning DNA adsorption affinity and density on metal oxide and phosphate for improved arsenate detection

2020

ChemNanoMat

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CeO2 nanoparticles or nanoceria is a very interesting enzyme mimic (nanozyme) with a diverse range of catalytic activities. Most of the previous studies focused on its redox chemistry for mimicking oxidase, peroxidase, and catalase‐like activities, and as a scavenger of reactive oxygen species. Considering CeO2 has both Ce(III) and Ce(IV) species and both interact strongly with inorganic phosphate, nanoceria has also been studied for its phosphatase‐like activity. We herein compared these species along with alkaline phosphatase (ALP). First, CeO2 and Ce(IV) have good activity using p‐nitrophenylphosphate (p‐NPP) as a substrate, while other metal ions failed to show this activity. Since a reaction product is inorganic phosphate and we observed an interesting enzyme kinetic profile, the effect of phosphate was studied, which inhibited both CeO2 and ALP. The inhibition constant was about 5‐fold smaller for CeO2. The inhibition effect of polyphosphates was even stronger. Due to the product inhibition effect, CeO2 is unlikely to be a typical multiple turnover nanozyme, and the system is self‐limited. For the other anions, only F− showed a moderate inhibition effect on the cerium species, while adsorption of DNA did not inhibit the activity. Finally, heat treated ALP lost the activity, but CeO2 and Ce(IV) remained active. This study has deepened our understanding of CeO2 as a phosphatase mimicking nanozyme, which could be useful for biosensing and chemical biology applications.

Section: Introductionmentioning

confidence: 99%

Self‐limited Phosphatase‐mimicking CeO₂ Nanozymes

2020

ChemNanoMat

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“…For example, it is well known that arsenate has a strong affinity with iron oxide and this has been used for remediation of arsenic species from the environment [23]. We took advantage of the competitive adsorption of DNA and arsenate for its detection [24][25][26]. Similarly, hydrogen peroxide can displace DNA from cerium oxide [27], while fluoride can enhance its catalytic activity [28].…”

Section: Introductionmentioning

confidence: 99%

Adsorption of Selenite and Selenate by Metal Oxides Studied with Fluorescent DNA Probes for Analytical Application

2017

J. Anal. Test.

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Selenium is a required micronutrient at low concentrations, while it becomes toxic at high concentrations. Inorganic selenium exists mainly as SeO 3 2-(selenite or Se(IV)) and SeO 4 2-(selenate or Se(VI)). Currently, few biosensors can effectively measure these selenium species in water. In this work, we study the adsorption of selenite/ selenate by various metal oxide nanoparticles including CeO 2 , CoO, Cr 2 O 3 , Fe 2 O 3 , Fe 3 O 4 , In 2 O 3 , Mn 2 O 3 , NiO, TiO 2 , and ZnO. Fluorescently-labeled DNA molecules are used as probes and first adsorbed on these oxides, resulting in quenched fluorescence. Upon addition of selenite, the DNA probes are displaced from the surface with fluorescence recovered for six out of the ten oxides, while the response to selenate was much lower in all the cases. The signaling is optimal below 400 mM NaCl at near neutral pH when Fe 3 O 4 nanoparticles were used. Quantitative studies were performed on three oxides with detection limits for selenite being 0.3 lM (CeO 2 ), 2.0 lM (Fe 3 O 4 ), and 3.0 lM (Fe 2 O 3 ), respectively. The system, however, is also responsive to a few other anions such as phosphate and arsenate. Therefore, it can be used as a method for analyzing selenium species when the system is known to be free of such competing anions. This study represents the first effort of designing selenite sensors using DNA as probes, and it may stimulate related work for this important analyte.

“…[85,86] It should be noted that researchers in this field have been advocating this method to be applied to many modified systems, especially by changing the substrate material. Although many other materials have been tested, such as MoS 2 , [87] various metal oxides, and other carbon-based materials, [46,88,89] GO was still used as a benchmark to compare the performance.…”

Section: Sensing Based On Desorption Of Probesmentioning

confidence: 99%

“…Typical proteins (e.g., bovine serum albumin [BSA]) do not interact with MONPs strongly enough to displace DNA (Figure 6F). It should be noted that the MONP/DNA system is susceptible to phosphate ions, which are prevalent in cell culture media, [ 88 ] although phosphate ions do not displace DNA from GO. Therefore, the problem of interfering agents in complex media for the simple adsorbed DNA probes needs to be carefully analyzed to ensure high sensitivity and specificity.…”

Section: Biosensors Using Physisorbed Dna Probesmentioning

confidence: 99%

Covalent and Noncovalent Functionalization of Graphene Oxide with DNA for Smart Sensing

Lopez

Advanced Intelligent Systems

2020

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Interfacing nanomaterials with DNA has resulted in the development of numerous biosensors, optimized for different targets and applications. Of all nanomaterials, graphene oxide (GO) has emerged as a prime sensing platform due to its high specific surface area, good aqueous stability, varied functional groups and desirable surface, and electrical and optical properties. This review starts with an introduction of GO and describes its physical and chemical properties. Then, the general strategies of interfacing DNA and GO to develop sensors are discussed. The trends in GO/DNA biosensor development are organized into classes based on the mode of DNA interaction with GO (physisorbed vs chemisorbed). Due to the intermediate DNA adsorption strength on GO, most of the sensors developed utilize physisorption of DNA to GO. Even within the realm of physisorbed probes, there are multiple sensing methods: direct adsorption, inhibited adsorption, competitive adsorption with the use of blocking agents, and tethered adsorption containing a strongly adsorbing block of DNA. Covalently linked DNA probes are also used to increase the biosensor stability. Each of these sensors has its advantages and disadvantages and the designs are discussed with representative examples in detail.