Direct analysis of trichloropyridinol in human saliva using an Au nanoparticles-based immunochromatographic test strip for biomonitoring of exposure to chlorpyrifos

Biosensors for saliva biomarkers

The analysis of salivary biomarkers has gained interest and is advantageous for simple, safe, and non-invasive testing in diagnosis as well as treatment. This chapter explores the importance of saliva biomarkers and summarizes recent advances in biosensor fabrication. The identification of diagnostic, prognostic and therapeutic markers in this matrix enables more rapid and frequent testing when combined with the use of biosensor technology. Challenges and future goals are highlighted and examined.

Enhanced visible light photocatalysis by TiO2-BN enabled electrospinning of nanofibers for pharmaceutical degradation and wastewater treatment

Boron nitride (BN) nanosheets are promising support materials for catalysts. A series of TiO₂-BN enabled electrospun nanofibers were synthesized for the photocatalytic treatment of ibuprofen and secondary wastewater effluent under visible light. X-ray photoelectron spectroscopy confirmed the existence of B-O-Ti bonds between the BN nanosheets and TiO₂ nanofibers, resulting in energy rearrangement, narrowed band gaps, and enhanced light utilization efficiency of the TiO₂-BN nanocomposites in the visible light spectrum. Transient photocurrent measurements revealed that the BN enhanced the transport of photogenerated holes from the bulk TiO₂ nanofibers to its surface, resulting in more efficient separation and less recombination of the charge carriers. A kinetic study of ibuprofen degradation indicated the enhanced photocatalytic performance of TiO₂-BN catalysts with a higher BN content in the nanocomposites. The kinetic rate constant of the TiO₂-10% BN catalysts was 10 times higher than that of the pure TiO₂ nanofibers. The degradation of organic contaminants in wastewater followed the same trend as ibuprofen and improved with increasing BN content. The stability of the TiO₂-BN nanocomposites as an effective solar photocatalyst was demonstrated by multiple cycles of wastewater treatment. The results proved that TiO₂-BN is an appealing photocatalyst under visible light.

Metal (Au, Pt) Nanoparticle-Latex Nanocomposites as Probes for Immunochromatographic Test Strips with Enhanced Sensitivity

The development of a sensitive and rapid diagnostic test for early detection of infectious viruses is urgently required to defend against pandemic and infectious diseases including seasonal influenza. In this study, we developed noble metal (Au, Pt) nanoparticle-latex nanocomposite particles for use as probes for immunochromatographic test (ICT) strips. The nanocomposite particles were conjugated with monoclonal antibody (mAb) to detect an influenza A (H1N1) antigen. For comparison, Au nanoparticles conjugated with mAb were also prepared. The lowest detectable concentrations of the influenza A antigen were found to be 6.25 × 10^-3 and 2.5 × 10^-2 HAU/mL for Au nanoparticle-latex and Pt nanoparticle-latex nanocomposite particles, respectively, whereas it was 4.0 × 10^-1 HAU/mL for Au nanoparticles. These results clearly demonstrated that the nanocomposite probes were more sensitive than conventional nanoparticle-based probes for ICT. To expand the versatility of the nanocomposite probes, the surfaces of the probes were functionalized with biotinylated proteins to enable modification of their surfaces with desired biotinylated antibodies through biotin-avidin binding.

Simultaneous detection of dual biomarkers from humans exposed to organophosphorus pesticides by combination of immunochromatographic test strip and ellman assay

A novel sandwich immunoassay based immunochromatographic test strip (ICTS) has been developed for simultaneously measuring both butyrylcholinesterase (BChE) activity and the total amount of BChE (including inhibited and active enzyme) from 70 μLpost-exposure human plasma sample. The principle of this method is based on the BChE monoclonal antibody (MAb) capable of acting as both capture antibody and detection antibody. The BChE MAb which was immobilized on the test line was able to recognize both organophosphorus BChE adducts (OP-BChE) and BChE and provided equal binding affinity, permitting detection of the total enzyme amount in post-exposure human plasma samples. The formed immunocomplexes on the test line can further be excised from the test-strip for subsequent off-line measurement of BChE activity using the Ellman assay. Therefore, dual biomarkers of BChE activity and phosphorylation (OP-BChE) will be obtained simultaneously. The whole sandwich-immunoassay was performed on one ICTS, greatly reducing analytical time. The ICTS sensor showed excellent linear responses for assaying total amount of BChE and active BChE ranging from 0.22 to 3.58nM and 0.22-7.17nM, respectively. Both the signal detection limits are 0.10nM. We validated the practical application of the proposed method to measure 124 human plasma samples from orchard workers and cotton farmers with long-term exposure to organophosphorus pesticides (OPs). The results were in highly agreement with LC/MS/MS which verified our method is extremely accurate. Combining the portability and rapidity of test strip and the compatibility of BChE MAb as both capture antibody and detection antibody, the developed method provides a baseline-free, low-cost and rapid tool for in-field monitoring of OP exposures.

Integrated immunochromatographic strip with glucometer readout for rapid quantification of phosphorylated proteins

A new technology to quantify phospho-p53¹⁵ by converting its content to the amount of glucose which is detectable by a glucometer was developed. An immunochromatographic test strip (ITS) was used as a disposable platform, where primary antibody (Ab₁)-modified Fe₃O₄ magnetic nanoparticles (Fe₃O₄-Ab₁) were settled on the test zone to capture both the target phospho-p53¹⁵ and the detection antibody (Ab₂)-glucose encapsulating liposome (GEL) conjugate. The measurement was based on the release and subsequent detection of glucose from Ab₂-GEL using a glucose meter (GM). The amount of glucose is proportional to the phospho-p53¹⁵ concentration from 0.1 to 50 ng mL^-1, the limit of detection is 50 pg mL^-1 (3S/N). The high sensitivity was a result of the huge number of glucose encapsulated in the liposome. Taking the advantage of low cost, widespread availability and portability of the test trip, together with the personal GM, the presented approach can be easily used to detect other disease biomarkers in medical diagnostics and environmental monitoring.

Defining Procedural Distress in the NICU and What Can Be Done About It

Procedural distress is a common occurrence in the NICU and is tied to attempts to support the life and development of vulnerable premature infants. We discuss the epidemiology of procedural distress and the potential negative consequences on infant neurodevelopment. We define procedural distress in the NICU and outline three approaches to limit or to reduce its detrimental effects including minimizing the number of procedures, instituting measures for developmentally supportive care, and using preemptively pharmacologic and nonpharmacologic analgesia. Despite the pervasiveness of procedural distress in the NICU, clinical and administrative measures are available to ameliorate possible harmful outcomes.

Sensitive inkjet printing paper-based colormetric strips for acetylcholinesterase inhibitors with indoxyl acetate substrate

A new paper-based biosensing approach has been developed for sensitive and rapid detection of acetylcholinesterase (AChE) inhibitors. The biosensing zone of the paper strip is constructed with an inkjet printing method, and the biomolecule AChE is immobilized into two layers of biocompatible sol-gel-derived silica ink with a "sandwich" form. Indoxyl acetate (IDA) is used as a chromogenic substrate, which is colorless and can be catalytically hydrolyzed into blue-colored indigo dipolymer. When the enzymatic activity of AChE is inhibited after incubation with organophosphate pesticides (OPs), there is a decreased hydrolysis of IDA accompanying with a drop in color intensity. Paraoxon and trichlorfon are used as the representative OPs in the assay. Due to the low solubility and high molar absorption coefficient of the IDA dipolymer product, the paper-based strip can form a neat blue sensing zone and shows obviously improved sensitivity with a limit of detection (LOD) of 0.01ngmL^-1 paraoxon and 0.04ngmL^-1 trichlorfon (S/N=3) and the LODs for visual detection are 0.03ngmL^-1 for paraoxon and 0.1ngmL^-1 for trichlorfon comparing with the previously reported colorimetric methods. The concentrations of paraoxon in apple juice samples are also detected, and the results are in accord well with these results from high-performance liquid chromatography, showing great potential for on-site detection of OPs in practical application. The developed assay can be used to qualitatively and semiquantitatively estimate with naked eyes and quantitatively assess OPs through image analysis.