Development of a novel electrochemical biosensor based on plastic antibodies for detection of STEAP1 biomarker in cancer.

STEAP1 is a cell surface protein of the STEAP family whose main function focuses on intercellular communication and cell growth. STEAP1 is considered a promising putative biomarker and a candidate target for prostate cancer treatment. For specific and selective detection of STEAP1, a molecularly imprinted polymers (MIP) was developed on a screen-printed electrode (C-SPE) whose surface was modified with a nanocomposite based on carbon nanotubes decorated with dendritic platinum nanoparticles (CNTs- PAH /Pt). Then, the MIPs were produced on the modified C-SPE by electropolymerization of a mixture of STEAP1 and a monomer (pyrrole-2-carboxylic acid). Then, the protein was removed from the polymeric network by enzymatic treatment with trypsin, which created the specific template cavities for further STEAP1 detection. Electrochemical techniques such as EIS and CV were used to follow the chemical modification steps of C-SPE. The analytical performance of the biosensor was evaluated by SWV in PBS buffer and in lysates of neoplastic prostate cancer cells (LNCaP) extracts. The MIP material showing a linear range from 130 pg/ml to 13 µg/ml. Overall, the biosensor exhibits essential properties such as selectivity, sensitivity and reproducibility for its application in medical and clinical research diagnosis and/or prognosis of prostate cancer.

Development of a biosensor for phosphorylated Tau 181 protein detection in Early-Stage Alzheimer's disease.

Alzheimer's disease (AD) is the most common form of dementia in the elderly, and there are still no reliable methods for its early detection. Recently, the phosphorylated protein Tau181 (p-Tau181) was identified as a highly specific biomarker for AD. Therefore, in this work, a new strategy for the development of an electrochemical-based immunosensor for the detection of p-Tau181 is described. For this purpose, a carbon screen-printed electrode (C-SPE) was modified with platinum nanoparticles decorated with multi-walled carbon nanotubes (MWCNTs- PAH /Pt) to enable antibody binding. Scanning electron microscopy, transmission electron microscopy, Raman and X-ray photoelectron spectroscopy were used to study the morphology and crystallinity of the nanomaterials. Cyclic voltammetry and square-wave voltammetry were performed to compare the electrochemical properties of these electrodes. Under optimal conditions, the developed immunosensor exhibited a linear range from 8.6 to 1100 pg/mL, and the detection limit was estimated to be 0.24 pg/mL. This device showed excellent reproducibility and stability with remarkable selectivity for p-Tau181 in serum samples. Overall, this device enables minimally invasive clinical evaluation of p-Tau181 level with high sensitivity through simple operation, which makes this device a promising tool for future point-of-care purposes that will contribute to the technological development of clinical diagnostics.

Total synthesis of nahuoic acid A via a putative biogenetic intramolecular Diels-Alder (IMDA) reaction.

Inspired by the biogenetic proposal of an intramolecular Diels-Alder (IMDA) cycloaddition, the total synthesis of natural product nahuoic acid A, a cofactor-competitive inhibitor of the epigenetic enzyme lysine methyl transferase SETD8, has been carried out. A non-conjugated pentaenal precursor was synthesized with high levels of stereoselectivity at seven stereogenic centers and with the appropriate control of double bond geometries. Although the IMDA reaction of the non-conjugated pentaenal using Me2AlCl for catalysis at -40 °C selectively afforded the trans-fused diastereomer corresponding to the Re-endo mode of cycloaddition, under thermal reaction conditions it gave rise to a mixture of diastereomers, that preferentially formed through the exo mode, including the cis-fused angularly-methylated octahydronaphthalene diastereomer precursor of nahuoic acid A. The natural product could be obtained upon oxidation and overall deprotection of the hydroxyl groups present in the Si-exo IMDA diastereomer.

Synthesis and Biological Evaluation of Tripartin, a Putative KDM4 Natural Product Inhibitor, and 1-Dichloromethylinden-1-ol Analogues.

The natural product tripartin has been reported to inhibit the N-methyl-lysine histone demethylase KDM4A. A synthesis of tripartin starting from 3,5-dimethoxyphenylacrylic acid was developed, and the enantiomers were separated by chiral HPLC. We observed that both tripartin enantiomers manifested an apparent increase in H3K9me3 levels when dosed in cells, as measured by western blot analysis. Thus, there is no enantiomeric discrimination toward this natural product in terms of its effects on cellular histone methylation status. Interestingly, tripartin did not inhibit isolated KDM4A-E under our assay conditions (IC50 >100 µm). Tripartin analogues with a dichloromethylcarbinol group derived from the indanone scaffold were synthesized and found to be inactive against isolated recombinant KDM4 enzymes and in cell-based assays. Although the precise cellular mode of action of tripartin is unclear, our evidence suggests that it may affect histone methylation status via a mechanism other than direct inhibition of the KDM4 histone demethylases.

Synthesis of the octahydronaphthalene core of nahuoic acid A via a B(C6F5)3-catalyzed intramolecular Diels-Alder (IMDA) reaction.

Model tetraenal 9b underwent intramolecular Diels-Alder cycloaddition in CH2Cl2 at -10 °C under catalysis by the bulky Lewis acid B(C6F5)3 to deliver as major components the cis-fused angularly-methylated octahydronaphthalene products, which are formed through the alternative exo orientations of the reacting moieties. One of these diastereomers features the relative and absolute configuration present in the core of nahuoic acid A, a natural product that acts as a cofactor-competitive inhibitor of the lysine methyl transferase SETD8. By contrast, catalysis of the reaction by Me2AlCl at -40 °C selectively afforded the trans-fused isomer resulting from the Re-endo orientation.