Search

Recombinant human erythropoietin (rHuEPO) is an important hormone drug that is used to treat several medical conditions. It is also frequently abused by athletes as a performance enhancing agent at sporting events. The time window of the rHuEPO in blood is short. Therefore, the rapid detection of rHuEPO use/abuse at points of care and in sports requires a selective analytical method and a sensitive sensor. Herein, we present a highly selective method for the rapid detection of rHuEPO in human blood plasma by a sensitive optical sensor. rHuEPO is selectively extracted from human blood plasma by a target-specific extractor chip and converted into a biothiol by reducing its disulfide bond structure. The formed biothiol reacts with a water soluble (E)-1-((6-methoxybenzo[d]thiazole-2-yl)diazenyl)naphthalene-2,6-diolHg(II) (BAN-Hg) optical sensor and causes its rapid decomposition. This leads to a rapid change in the sensor color from blue to pink that can be observed by the naked eye. The optical sensor was used to quantify rHuEPO in the concentration range 1 × 10−8 M to 1 × 10−12 M by UV–Vis spectroscopy. For the screening of blood plasma, an EPO-specific extractor chip was synthesized and used to selectively extract the protein from the biological matrix prior to its conversion into biothiol and quantification by the optical sensor. Since many proteins have a disulfide bond structure, the new method has strong potential for their rapid sensitive and selective detection by the BAN-Hg sensor and UV–Vis spectroscopy. [ABSTRACT FROM AUTHOR]

Carcinoembryonic antigen (CEA) is the gold standard biomarker for the clinical diagnosis of cancers diseases. Accurate, fast, and sensitive screening of CEA plays an important role in cancer disease detection and prognosis. This work reports the development of a new stimuli-responsive biosensor that determines the CEA blood plasma concentration within 10 min. Tert-butyl carbonate Naphthalene-flanked diketopyrroloprrole (mono-TBC-DPPN) fluorescent agent was synthesised, characterised and immobilised gold nanoparticles to develop the stimuli-responsive sensor. The target protein was purified from spiked plasma (from human blood), using an antibody-coated gold substrate. The purified CEA was then chemically modified to provide thiol groups (SH) that interact with the mono-TBC-DPPN on the surface of the stimuli-responsive biosensor to spontaneously displace it, thus leading to its fluorescence emission at 532 nm to a turn on. The new method and sensor was implemented to quantify CEA in spiked blood plasma down to 10 pg.mL−1 within 45 min (35 min for the protein purification and modification and 10 min for its quantification using the sensor) [Display omitted] • New stimuli-responsive probe for the fluorescence detection of CEA. • The probe is utilised in a new paper sensor to screen CEA down to 10 pg.mL−1. • The cysteine residues of CEA stimulate the probe desorption and its FL turn on. • A new method to purify and quantify CEA in blood within 45 min. • The sensor can be extended to screen many cysteine-containing biomarkers. [ABSTRACT FROM AUTHOR]

Cardiac troponin I (cTnI) is a sensitive biomarker for cardiovascular disease (CVD). Rapid determination of cTnI concentration in blood can greatly reduce the potential of significant heart damage and heart failure. Herein, we demonstrate a new electrochemical immunosensor for selective affinity binding and rapid detection of cTnI in blood plasma by an electrochemical method. A conductive film of "poly 2,5-bis(2-thienyl)3,4-diamine-terthiophene (PDATT)" was deposited onto an Indium Tin Oxide (ITO) electrode using chronoamperometry. Anti-cardiac troponin I antibody was then attached to the two amine (NH 2) groups substituted on the central thiophene of terthiophene repeating unit of the polymer chain via amide bond formation. The gaps on the surface of the antibody coated immunosensor were backfilled with bovine serum albumin (BSA) to prevent nonspecific binding of interfering molecules. Differential pulse voltammetry (DPV) was used to determine cTnI upon the formation of cTnI immunocomplex on the sensing surface, appearing a peak at 0.27 V. The response range was 0.01–100 ng mL−1 with limit of quantification down to 0.01 ng mL−1. The developed immunosensor was used to determine cTnI in spiked blood plasma without interference from cardiac troponin T (cTnT). Therefore, this new sensor can be utilised for the detection of cTnI biomarker in pathological laboratories and points of care in less than 15 min. [Display omitted] • Efficient chronoamperometry method to develop continuous conductive polymer film. • Sensitive immunosensor for the extraction and detection of cardiac troponin I by DPV. • The new immunosensor is highly selective towards cardiac troponin I over troponin T. • The sensor has a low LOQ (0.01 ng mL−1), and good reproducibility (3.7%) for cTnI. • The new sensor is rapid and can screen cardiac troponin I in blood plasma in 15 min. [ABSTRACT FROM AUTHOR]

• New target-specific extractor nanomaterial for TNF-α extraction. • New SERS quenching sensor for the determination of TNF-α. • Highly sensitive method for the quantification of TNF-α in blood down to 10−14 M. • Inexpensive gold coated copper oxide nanomaterial for the screening of proteins. • Novel utilisation of the protein disulfide bond structure for their determination by SERS. Tumor necrosis factor alpha (TNF-α) is a cytokine that plays a critical role in medical conditions such cardiovascular diseases, rheumatoid arthritis, inflammatory bowel disease, Alzheimer's and cancer. Herein, we present a new method for the determination of TNF-α by surface enhanced Raman spectroscopy (SERS). A new benzothiazole azo dye (BAN) was used as a Raman probe to detect the cytokine after its selective extraction from blood plasma using a target-specific antibody-functionalised extractor chip. The disulfide bond structure of the extracted TNF-α was reduced to generate free sulfhydryl (SH), terminal groups that adsorb preferentially onto a BAN-functionalised SERS substrate and displace the BAN Raman reporter on the substrate surface. This causes the SERS spectrum of BAN to quench proportionally with the cytokine concentration. Using this SERS quenching sensor, TNF-α was quantified down to 1 × 10−14 M (173 pg/L). The quantification of the cytokine by the SERS quenching method was cross-validated against enzyme-linked immunosorbent assay (ELISA) and the percent agreement between the two measurements was found to be 93.39 %. Since many proteins and peptides have disulfide bonds in their molecular structures, the new SERS quenching method can be extended for their ultrasensitive quantification after selective extraction from biological fluids. [ABSTRACT FROM AUTHOR]