Light-modulated ion binding: towards calibrationless sensors

Emerging technologies create new application fields but few of them require that we completely rethink our approach in preparation and characterization of sensors. The vision of internet scale wireless sensor networks (WSNs) requires the deployment of enormous numbers of sensors. This necessarily means that the cost of each sensor must be brought down significantly if this vision is to be realized. An ideal solution for this problem would be a sensor that does not interact with its environment in any way until there is a need for measurement. Upon the measurement, the sensor’s surface is completely regenerated and returned into the state as before the measurement. This step is critical as it ensures that the measurement did not any effect on the sensor hence no calibration is necessary. In our work, we use compounds that indeed can be switched between the active and passive state using light. Most commonly used compounds are so called spiropyrans (SP) and spirooxazines (SO). Here we show the recent advance in preparation of reversible, light-modulated sensors using surface immobilised SP/SO derivatives. A further attractive property of these materials is that they are inherently self-indicating through striking colour changes that enable the state to be easily determined (active vs. passive), and the presence of a bound guest to be detected. These spectral changes enable a range of self-diagnostic tests to be incorporated that enable binding events to be controlled at the surface interface, and for real binding events to be distinguished from artefacts arsing from changes in light intensity, or photobleaching of the active component. We have identified most notable problems for utilization of these compounds in “calibrationless” sensors such as relatively weak binding constants, photodegradation, and unfavourable kinetics of switching between the active and passive state and we demonstrate our approach in solving these problems

Spiropyran-based reversible, light-modulated sensing with reduced photofatigue

Switchable materials have tremendous potential for application in sensor development that could be applied to many fields. We are focusing on emerging area of wireless sensor networks due to the potential impact of this concept in society. Spiropyran-based sensors are probably the most studied type of photoswitchable sensing devices. They suffer from many issues but photofatigue, insufficient selectivity and lack of sensitivity are probably the most important characteristics that hinder their wider application. Here, we are address these issues and demonstrate that covalent attachment of modified spiropyran into a polymeric film significantly reduces photodegradation. The observed signal loss after 12th cycle of switching between the spiropyran and merocyanine forms is only about 27% compared to the loss of 57% of the initial signal in an equivalent experiment based on non-immobilized spiropyran. This has enabled us to demonstrate at least five reversible cycles of detection of an ion of interest (in our case H+) with minimal signal loss. Furthermore, we demonstrate that the sensitivity can be increased by incorporation of additional binding groups in the parent spiropyran molecule. Using molecular modelling to calculate the relevant bond lengths as a measure of interaction between MC and H+, the calculated increase of H-bond strength is approximately an order of magnitude for a derivative containing a methoxy group incorporated in the o-position of the parent spiropyran in comparison to the equivalent unsubstituted phenol. This theoretical result was found to correspond very well with experimental observation. As a result, we have increased the sensitivity to H+ by approximately one order of magnitude

Novel synthesis and characterisation of 3,3-dimethyl-50-(2-benzothiazolyl)- spironaphth(indoline-2,30-[3H]naphth[2,1-b] [1,4]oxazine) derivatives

Novel modified spirooxazines (SOs) with additional chelating groups were synthesised and the crystal structure of one of these was determined. UV–vis spectroscopic characterization of the photoisomerization of the SO derivatives shows that the photochromic behaviour is altered with Zn2+ coordination. In particular, addition of a group as in carboxylic acid 5 to the indole section of the SO increases the lifetime of the merocyanine Zn 2+ complex by 20-fold compared to the methylated indole 6

Correlation between Trace Element Levels in Iraqi Breast Cancer Patients

Breast Cancer (BC) is the most common  disease  in the human body in both sex , male and female ,Trace  elements (TEs) like copper (Cu); zinc (Zn) and  iron (Fe)  have a vital  role in biological and  metabolic effects  including activation or inhibition of  enzymatic reaction, reactive oxygen species (ROS), competition between trace elements and metal proteins for binding positions and modifications in the permeability of cellular membranes which affect on cancers events.This  paper reviews measured  trace elemental concentrations of cancerous and noncancerous blood sample by drawing 5 ml of venous blood  from all patient and control (healthy persons) ,the serum was separated then used to measure  the  Zn,Cu and Fe. by using. a convenient colorimetric assay. The statistical significant association was determined, the p values is larger than 0.05  so the data  considered statistically significant ,and there is a difference in the levels of trace elements (Zn, Cu and Fe) in four groups ; the median  of Zn and Cu were highest in control group compared to the rest groups ,the median of  Fe is highest in benign group compared to the rest groups

5′,6-Dichloro-1′,3′,3′-trimethyl­spiro­[2H-1-benzopyran-2,2′-indoline]

In the crystal structure of the title compound, C19H17Cl2NO, the indoline and benzopyran ring systems are approximately perpendicular to each other. The indoline ring is in an envelope conformation with the spiro C atom as the flap. The N atom of the indoline ring forms a pyramidal environment, the sum of the angles at this atom being 352.46°

Business email compromise: a systematic review of understanding, detection, and challenges

Business Email Compromise (BEC) is a widespread fraud targeting businesses and individuals to obtain financial benefits and gain access to highly sensitive data. BEC fraud significantly impacts almost all organizations worldwide, resulting in substantial losses. Despite its prevalence, there is a shortage of research on understanding and protecting against this fraud. Consequently, this paper aims to survey existing BEC detection techniques. It first provides an overview of the methods and strategies used by attackers in BEC schemes. It also reviews existing BEC detection and prevention techniques, including both technical and non-technical solutions. The strengths of each technique are objectively discussed, and their limitations are critically analyzed. Finally, this study offers a thorough set of current challenges in BEC detection and outlines future research directions, providing valuable guidance for improving security measures against BEC fraud.</p

UV-Spectroscopy for Original Honey and Comparing with Some Types of Honey in Iraqi Market to Investigate the Cheat in Them

Abstract Honey is a medication material and its very expensive, so some people try to cheat honey by adding sugar solution to it. In this work, a method was done to investigate the ratio of cheat or sugar solution in honey. UV-spectroscopy was done for original honey. UV-spectroscopy for several mixtures containing different ratios for honey and sugar solution was done to make normalization curve. Different types of honey were collected from Iraqi market and UV-spectroscopy was done for these types. For every graph done for these honey types collected from Iraqi market, maximum absorbance point was taken and applied on the normalization curve. After application on the normalization curve, the ratios of honey and sugar solution were found for every type of honey collected.</jats:p

Chloride Selective Calix[4]arene Optical Sensor Combining Urea Functionality with Pyrene Excimer Transduction

A neutral 2-site chloride selective compound has been developed (3), based on a 1,3-alternate tetrasubstituted calix[4]arene providing a preorganized supramolecular scaffold. The resultant supramolecular cavity is among the first to combine urea functional groups bridged with single methylene spacers to pyrene moieties. It combines a naturally and synthetically proven H-bonding system with the elegant ratiometric fluorescent signaling properties of an intramolecular pyrene excimer system, triggered by conformational changes upon anion coordination. The excimer emission of 3 is quenched, with a simultaneous rise in the monomer emission solely by the chloride anion among a wide variety of anions tested. 3 has an association constant of 2.4 × 104 M-1 with chloride. The suitability and advantages of ratiometric optical sensor compounds like 3 for use in practical sensor devices is discussed. 3 has an LOD of 8 × 10-6 M with chloride in acetonitrile-chloroform (95:5 v/v). A dynamic fluorescence study revealed a response time of <3 s. A recently developed and simple HPLC-based purification method complimented conventional organic work up methods to yield pure product