A review on recent advances in the applications of surface-enhanced Raman scattering in analytical chemistry

Covalent organic frameworks are a class of extended crystalline organic materials that possess unique architectures with high surface areas and tuneable pore sizes. Since the first discovery of the topological frameworks in 2005, COFs have been applied as promising materials in diverse areas such as separation and purification, sensing or catalysis. Considering the need for renewable and clean energy production, many research efforts have recently focused on the application of porous materials for electrochemical energy storage and conversion. In this respect, considerable efforts have been devoted to the design and synthesis of COF-based materials for electrochemical applications, including electrodes and membranes for fuel cells, supercapacitors and batteries. This review article highlights the design principles and strategies for the synthesis of COFs with a special focus on their potential for electrochemical applications. Recently suggested hybrid COF materials or COFs with hierarchical porosity will be discussed, which can alleviate the most challenging drawback of COFs for these applications. Finally, the major challenges and future trends of COF materials in electrochemical applications are outlined.

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Covalent organic frameworks (COFs) for electrochemical applications

NeuroToxicology 31 (2010) 575–581 Contents lists available at ScienceDirect NeuroToxicology Review The neurotoxicity of environmental aluminum is still an issue Stephen C. Bondy * Program in Environmental Toxicology, Division Occupational and Environmental Health, Department of Medicine, University of California, Irvine, CA 92697-1825, USA A R T I C L E I N F O A B S T R A C T Article history: Received 18 September 2009 Received in revised form 24 March 2010 Accepted 10 May 2010 Available online 27 May 2010 Evidence for the neurotoxicity of extended exposure to low levels of aluminum salts is described using an animal model treated with aluminum at low levels reﬂecting those found in some water supplies. Emphasis is given to the potential role of aluminum in acceleration and promotion of some indices characteristic of brain aging. These hallmarks include the appearance of excess levels of inﬂammation in speciﬁc brain areas. Aluminum salts can increase levels of glial activation, inﬂammatory cytokines and amyloid precursor protein within the brain. Both normal brain aging and to a greater extent, Alzheimer’s disease are associated with elevated basal levels of markers for inﬂammation. These are not attributable to obvious exogenous stimuli and may reﬂect the lifespan history of the organism’s immune responses. It is possible that aluminum salts can act as a subtle promoter of such apparently unprovoked responses. s 2010 Elsevier Inc. All rights reserved. Keywords: Aluminum Drinking water brain aging Alzheimer’s disease Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aluminum is environmentally prevalent and ingested by humans. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . There is an epidemiological relation between chronic aluminum exposure and the incidence of Alzheimer’s disease . . . . . . . . . . . Aluminum exposure may also promote the onset of Parkinson’s disease. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acute exposure to aluminum can cause clinical neurotoxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Elevated levels of intrinsic inﬂammation are associated with neural aging and this is exacerbated in several neurodegenerative diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Low levels of aluminum in drinking water of experimental animals, elevate basal levels of inﬂammatory activity within the CNS Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. Introduction This review on the potential neurotoxic hazard posed by aluminum focuses on distinguishing between those aspects of aluminum neurotoxicity that are widely accepted and not controversial, and those aspects that are suggestive but not fully established. The work of this laboratory over the past 12 years is described and this falls into the latter classiﬁcation, adding to the body of evidence increasingly implicating aluminum as a potentially hazardous environmental agent. The most accepted facts relating to aluminum include: (i) it’s widespread prevalence and level of human consumption, (ii) the * Correspondence address: Department of Community and Environmental Medicine, University of California at Irvine, Irvine, CA 92697-1825, USA. Tel.: +1 949 824 8077; fax: +1 949 824 2793. E-mail address: scbondy@uci.edu. 0161-813X/$ – see front matter s 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.neuro.2010.05.009 known neurotoxicity of high levels of aluminum, and (iii) a repeated epidemiological correlation between ingested aluminum and the incidence of Alzheimer’s disease. Another relevant area of widespread consensus is the tendency of the aging brain to express elevated levels of inﬂammation and the further exacerbation of this state in several neurodegenerative diseases. Less accepted is the evidence that aluminum can be a causal factor in promoting Alzheimer’s disease. This area has been handicapped by earlier erroneous reports of heightened levels of aluminum in amyloid plaques. Tissue aluminum levels are notoriously difﬁcult to determine and later more reliable ﬁndings leading to similar conclusions have been overshadowed by these original reports. The main objective of our more recent studies has been to study the effects of extended exposure of experimental animals to levels of aluminum that have relevance for the human population. Demon- stration that these can provoke cerebral inﬂammatory responses resembling those that are found with brain senescence, can provide a mechanistic link to epidemiological reports.

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The neurotoxicity of environmental aluminum is still an issue - eScholarship

This article discusses three aspects of inner filter effect (IFE) in fluorescence spectroscopy. (i) First, IFE as undesirable in fluorescence measurements: IFE results in non-linear fluorescence response of the analyte under study and it has been verified that IFE cannot be eliminated; it can either be minimized or corrected for intensity loss. Over the years, researchers have proposed many intensity correction methods to avoid IFE related issues. Often analysts using fluorescence spectroscopy, knowingly or unknowingly, ignore IFE or use an inappropriate intensity correction method. Herein, we have highlighted the basis and significances of various correction models that are proposed since 1970s to till date. (ii) Second, IFE mediated concentration dependent red shift (CDRS) as an analytical tool: the conventional fluorescence measurements and IFE correction strategies cannot be applied in analysis of optically dense multi-fluorophoric samples like oils, petrochemicals, biological samples and food samples etc. The strategy for exclusive inclusion of IFE and IFE induced CDRS as characteristics of the system for development of fluorescence based assay, towards maximizing fluorescence sensitivity of optically dense multi-fluorophoric systems, have been discussed. (iii) Third, IFE based sensing: when the sample contains chromophores, which absorb either at the excitation or at the emission wavelength range of the fluorophore, then the chromophores act as a filter. Thus tuning either the absorber or fluorophore concentration will lead to development of fluorescence based assay for a selective analyte. Principles and protocols are described to identify whether a sensing event is due to IFE or any other fluorescence mechanism. Additionally, a brief description is given on advanced findings and progresses made in sensing of for various classes of analytes in the recent past, using IFE concept. The second and third aspect combined together serve as a tool towards enhancing sensitivity of fluorescence measurement.

Inner filter effect in fluorescence spectroscopy: As a problem and as a solution

https://pubs.rsc.org/en/content/articlepdf/2020/cc/d0cc05650b

Electrochemical non-enzymatic glucose sensors: recent progress and perspectives

Carbon cloth-supported nanorod-like conductive Ni/Co bimetal MOF: A stable and high-performance enzyme-free electrochemical sensor for determination of glucose in serum and beverage.

A sensitive and selective approach for detection of tetracyclines using fluorescent molybdenum disulfide nanoplates.

Superhydrophobic SERS substrates based on silver dendrite-decorated filter paper for trace detection of nitenpyram.

Electrochemical behavior of reduced graphene oxide/cyclodextrins sensors for ultrasensitive detection of imidacloprid in brown rice.

Hydroquinone (HQ) is a major phenol compound pollutant derived from industrial wastewater. Its content in environmental water is closely related to the water quality. Thus, it is in great need to develop facile, sensitive and selective detection methods for HQ. In this paper, an effective and selective HQ detection probe was fabricated based on novel silicon quantum dots (SiQDs), which were synthesized by a one-step hydrothermal method. Such SiQDs exhibited good water solubility and intensely green fluorescence. Interestingly, their fluorescence can be significantly quenched upon addition of HQ, which is attributed to the electron transfer from SiQDs to the generated 1,4-benzoquinone, and the inner filter effect of SiQDs-1,4-benzoquinone complex. This SiQD probe can detect HQ in a wide concentration range from 6 to 100 μM, with a detection limit of 2.63 μM. More importantly, compared with other reported methods, this probe can eliminate the interference from catechol (CC) and resorcinol (RS), and gives new insight on the discrimination HQ from its isomers. Furthermore, this fluorescent probe was also successfully applied for the determination of HQ in real water samples with satisfactory recoveries, indicating the reliability and potential application of this fluorescent probe for monitoring HQ.

Qinzhi Wang

Papers

Carbon cloth-supported nanorod-like conductive Ni/Co bimetal MOF: A stable and high-performance enzyme-free electrochemical sensor for determination of glucose in serum and beverage.

A sensitive and selective approach for detection of tetracyclines using fluorescent molybdenum disulfide nanoplates.

Superhydrophobic SERS substrates based on silver dendrite-decorated filter paper for trace detection of nitenpyram.

Electrochemical behavior of reduced graphene oxide/cyclodextrins sensors for ultrasensitive detection of imidacloprid in brown rice.

Highly selective and sensitive fluorescence detection of hydroquinone using novel silicon quantum dots