Fluorescent detection of an anthrax biomarker based on PVA film

Abstract

Due to the dangerous nature of anthrax, the development of a cost-effective, sensitive and field-portable sensor for the anthrax biomarker--calcium dipicolinate (CaDPA)--is of exceptional significance for both military and civilian use. Herein, a flexible polymer-film-based ratiometric sensor for detecting CaDPA was demonstrated. A reference dye and a probe ligand were covalently immobilized onto the film surface through a highly selective and efficient "click chemistry" reaction. The reference dye, whose fluorescence intensity does not change with varying amounts of CaDPA, offers a non-interfering internal calibration. The ethylenediaminetetraacetic acid (EDTA)-based ligand binds with Eu(III) and serves as the probe. In the absence of CaDPA, the film sensor exhibited almost no red fluorescence because the Eu(III) ions themselves give no emission without sensitization by CaDPA owing to the small molar absorption coefficients of Eu(III) ions. The presence of CaDPA induces a significantly enhanced emission intensity of the sensor, and thereby enables the film as a ratiometric sensor for CaDPA. This sensor can selectively detect CaDPA in water with a detection limit of 100 nM. Moreover, this sensor exhibited strong anti-interfering capability, it can not only be used in milieus that contain various amino acids and some biologically-abundant cations, but can also be usable in some biological fluids such as urine and serum. This test-paper-like film sensor is suitable for portable field analysis and needs no extra protective measures during transport due to its flexibility, and it can easily be separated from the analyte solution after the detection.

Luminescent films for chemo- and biosensing

“…On the other hand, the development of inorganic luminophores with water-soluble ligands, such as quantum dots (QDs) [13][14][15] and luminescent metal nanoclusters (NCs), 16,17 seems to be an alternative method but encounters new problems (e.g., limited variety). Luminescent films can be transformed easily into a device format with several unique advantages: (1) luminescent films with any shape and size (dependent on the substrate pattern) can be easily fabricated for various needs and occasions; [29][30][31] (2) they are easily stored and transported as a result of a good chemical stability of luminophores in the solid state; 32,33 (3) there does not exist invasive interference since the detection is usually performed in the luminescent films with no external addition; 25,34 (4) luminescent films enable real-time detection of the analyte; [35][36][37] and (5) luminescent films can be regenerated by washing them with suitable solvents. [26][27][28] In the past several decades, it is preferable to develop luminescent films consisting of various kinds of luminophores and functional materials to overcome the drawbacks of luminescent probes in solution for chemo-/bio-sensing.…”

Review: Poly(vinyl alcohol) Functionalizations and Applications

“…In view of detecting Bacillus anthracis, a serious pathogen for the disease anthrax, and thus for human safety, Ma et al [74] PVA grafted on multwalled carbon nanotubes, PVA-g-MWCNT, and on graphene oxide, PVA-g-GO, were conceived as drug nanocarriers [75,76] . Among the drugs loaded by these nanomaterials were camptothecin (CPT) and ellagic acid, anticancer drugs.…”

A Ratiometric Fluorescent Nano-Probe for Rapid and Specific Detection of Tetracycline Residues Based on a Dye-Doped Functionalized Nanoscaled Metal–Organic Framework

“…Researchers have developed some lanthanide-based on–off sensors to measure target concentrations [14,15]. However, most of these sensors measure the concentration of the target only by the change of fluorescence intensity, so the influence caused by instrument or environmental factors is inevitable [16].…”