Selective recognition of a saccharide-type tumor marker with natural and synthetic ligands: a new trend in cancer diagnosis

Fluorophore-Probed Curdlan Polysaccharide Chemosensor: "Turn-On" Oligosaccharide Sensing in Aqueous Media

The ability to sense saccharides in aqueous media has attracted much attention in multidisciplinary sciences because the detection of ultrahigh concentrations of sugar chains associated with serious diseases could lead to further health promotion. However, there are notable challenges. In this study, a rhodamine-modified Curdlan (Rhod-Cur) chemosensor was synthesized that exhibited distinctive fluorescence "turn-on" responses. Rhod-Cur exhibited simultaneous sensitive and selective sensing of clinically useful acarbose with a good limit of detection (5 μM) from among those of the saccharides examined. The (chir)optical properties of Rhod-Cur were elucidated using UV/vis, fluorescence, excitation, and circular dichroism spectroscopies; lifetime measurements and morphological studies using atomic force and confocal laser scanning microscopy and dynamic light scattering techniques revealed that the fluorescence "turn-on" behavior originates from globule-to-coaggregation conversion upon insertion of the oligosaccharides in the dynamic Cur backbone.

Non-enzymatic D-glucose plasmonic optical fiber grating biosensor

Saccharide sensors represent a broad research area in the scope of sensing devices and their involvement in the medical diagnosis field is particularly relevant for cancer detection at early stage. In that context, we present a non-enzymatic optical fiber-based sensor that makes use of plasmon-assisted tilted fiber Bragg gratings (TFBGs) functionalized for D-glucose biosensing through polydopamine (PDA)-immobilized concanavalin A (Con A). Our probe allows a live and accurate monitoring of the PDA layer deposition leading improved surface biochemistry. The SPR shift observed was assessed to 3.83 ± 0.05 nm within 20 min for a 2 mg/mL dopamine solution. Tests performed in different D-Glucose solutions have revealed a limit of detection close to 10^-7 M with the highest sensitivity in the 10^-6 to 10^-4 M range. This configuration has the capability to overcome the limitations of current enzyme-based solutions.

Pentamethinium salts as ligands for cancer: Sulfated polysaccharide co-receptors as possible therapeutic target

A series of pentamethinium salts with benzothiazolium and indolium side units comprising one or two positive charges were designed and synthesized to determine the relationships among the molecular structure, charge density, affinity to sulfated polysaccharides, and biological activity. Firstly, it was found that the affinity of the pentamethinium salts to sulfated polysaccharides correlated with their biological activity. Secondly, the side heteroaromates displayed a strong effect on the cytotoxicity and selectivity towards cancer cells. Finally, doubly charged pentamethinium salts possessing benzothiazolium side units exhibited remarkably high efficacy against a taxol-resistant cancer cell line.

Optical probes and sensors as perspective tools in epigenetics

Modifications of DNA cytosine bases and histone posttranslational modifications play key roles in the control of gene expression and specification of cell states. Such modifications affect many important biological processes and changes to these important regulation mechanisms can initiate or significantly contribute to the development of many serious pathological states. Therefore, recognition and determination of chromatin modifications is an important goal in basic and clinical research. Two of the most promising tools for this purpose are optical probes and sensors, especially colourimetric and fluorescence devices. The use of optical probes and sensors is simple, without highly expensive instrumentation, and with excellent sensitivity and specificity for target structural motifs. Accordingly, the application of various probes and sensors in the recognition and determination of cytosine modifications and structure of histones and histone posttranslational modifications, are discussed in detail in this review.

Recent developments in blood glucose sensors

Diabetes has recently become a leading cause of death worldwide. To date, although there is no means to cure or prevent diabetes, appropriate medication and blood sugar monitoring can enhance treatment efficiency, alleviate the symptoms, and diminish the complications of the condition. This review article deals with current growth areas in the market for blood glucose sensors and possible future alternatives, which are generally considered to be the point sample test and the continuous glucose monitor (CGM). Most glucose sensors are enzyme-based, whereas others are enzyme-free. The former class is sensitive and some products are extensively employed for daily self-sensing and in hospital environments as reliable diagnostic tools. The latter class, particularly the boronic acid fluorescent sensor, is facile and extremely promising. Practicality demands that all types of sensors offer accuracy, specificity, and real-time detection.

New method for recognition of sterol signalling molecules: methinium salts as receptors for sulphated steroids

In this work, we studied indolium and benzothiazolium pentamethine salts 1-3 as novel type of receptors for the recognition of sulphated signalling molecules (sulphated steroids: oestrone, pregnenolone and cholesterol sulphate). A recognition study was performed in an aqueous medium (1mM phosphate buffer (H2O:MeOH; 99:1 (v/v))) at pH 7.34. The tested salts displayed a high affinity for these sulphated analytes, mainly for cholesterol sulphate. However, no interaction between the salts and control, non-sulphated sterol analytes (cholesterol and bile acid) was observed. The highest affinity for the sulphated steroids was observed for benzothiazole salt 1. This salt also displayed different spectral behaviour from that observed for carbocyanine salts 2 and 3. In this presence of cholesterol sulphate, benzothiazole salt 1 displayed significant spectral changes depending on the medium used: a blue shift in the aqueous medium and a red shift in the methanolic one (H2O:MeOH; 2:1 (v/v)). Subsequently preliminary in vivo study showed that, salt 1 significantly inhibits a growth of breast carcinoma on Nu/nu mice model.

Sugar recognition: designing artificial receptors for applications in biological diagnostics and imaging

At the cellular level, numerous processes ranging from protein folding to disease development are mediated by a sugar-based molecular information system that is much less well known than its DNA- or protein-based counterparts. The subtle structural diversity of such sugar tags nevertheless offers an excellent, if challenging, opportunity to design receptors for the selective recognition of biorelevant sugars. Over the past 40 years, growing interest in the field of sugar recognition has led to the development of several promising artificial receptors, which could soon find widespread use in medical diagnostics and cell imaging.

Molecular recognition with boronic acids-applications in chemical biology

Small molecules have long been used for the selective recognition of a wide range of analytes. The ability of these chemical receptors to recognise and bind to specific targets mimics certain biological processes (such as protein-substrate interactions) and has therefore attracted recent interest. Due to the abundance of biological molecules possessing polyhydroxy motifs, boronic acids-which form five-membered boronate esters with diols-have become increasingly popular in the synthesis of small chemical receptors. Their targets include biological materials and natural products including phosphatidylinositol bisphosphate, saccharides and polysaccharides, nucleic acids, metal ions and the neurotransmitter dopamine. This review will focus on the many ways in which small chemical receptors based on boronic acids have been used as biochemical tools for various purposes, including sensing and detection of analytes, interference in signalling pathways, enzyme inhibition and cell delivery systems. The most recent developments in each area will be highlighted.