Application of HRP-streptavidin bionanoparticles for potentiometric biotin determination.

Biotin is widely used in infant formula to prevent biotin deficiency of newborn babies and in beauty products as nutritional supplements for coenzymatic functions and having strong nails, shiny hair, and skin over the last few years. There is a need for the development of a fast, simple and reusable assay method to perform biotin determination at very low concentrations. Biotin determination has achieved with a prepared potentiometric biotin sensor that has a very wide concentration range (10-15M-10-7M) and a lower detection limit (0.3 10-15M) with a very good regression coefficient (0.9925). A quick response (7 min), good accuracy (recovery 100.4-103.7%), reproducible, reusable (10 times), and long-term stability (3 months) have been obtained using the prepared potentiometric sensor. The obtained results have proved that the prepared potentiometric sensor can be used for biotin determination in real samples.

Graphenoxide Cross-Linker Based Potentiometric Biosensor Design for Sarcosine Determination.

BACKGROUND: Sarcosine, also known as N-methyl glycine, is a natural amino acid that is an intermediate and by product in glycine synthesis and degradation. Recently found in many peptides, sarcosine has been researched as a newly accepted prostate cancer marker. The increased concentration of sarcosine in blood serum and the urine showed that malignancy of measured prostate cancer cells is active. OBJECTIVE: In this article, we aimed to design a potentiometric biosensor for detection of sarcosine with a low detection limit, high selectivity, short response time, wide linear range, and satisfactory long-term stability. METHODS: In this article, we developed a new Graphene oxide (GFOX) photosensitive cross-linker based potentiometric biosensor based on the AmiNoAcid (monomer) Decorated and Light Underpinning Conjugation Approach (ANADOLUCA) method. The functional groups determined using Raman, FT-IR, XPS analyzes, and surface characterization, the morphology of synthesized GFOX photosensitive cross-linker were determined by TEM and AFM studies. Then, the performance of the GFOX based potentiometric biosensor has been evaluated. RESULTS: When the usage of the developed GFOX doped potentiometric biosensor against sarcosine determination, it was found that 10-4 mM sarcosine was determined in 60 seconds in the solution. In addition, the detection limit of the GFOX doped potentiometric biosensor was found to be 9.45x10-7 mM, and the linear potentiometric biosensor was found to be in the concentration range of 10-1 to 10-5 mM. The selectivity studies of the developed potentiometric biosensor were investigated using glycine solutions, and it was determined that GFOX doped potentiometric biosensor was more selective against sarcosine. Besides this, a reusability test using 10-3 mM sarcosine solution showed that reproducible studies were performed without the loss of potential of designed potentiometric biosensor and no loss of sensitivity. CONCLUSION: After applying the framework, we get a new potentiometric biosensor for sarcosine determination. GFOX photosensitive cross-linker was used in designing potentiometric biosensors, and this increased the stability and efficiency of the biosensor. Therefore, the developed potentiometric biosensor for sarcosine determination could be easily used for the early diagnosis of prostate cancer.

A new potentiometric platform: Antibody cross-linked graphene oxide potentiometric immunosensor for clenbuterol determination.

An immunosensor is based on the signal measurement obtained upon the reaction of an antibody antigen complex. It plays a significant role in various fields such as environmental analysis, production monitoring, drug detection or screening, veterinary medicine, and animal food. In this study, an antibody crosslinked graphen oxide (GO)-based potentiometric sensor has been developed for fast, simple, and economical detection of clenbuterol. In this context, the photosensitive amino acid bound GO platform is synthesized and used for the preparation of electrode material. Then, polymeric structure is characterized by infrared spectroscopy, and the performance of immunonano platform prepared by potentiometric sensor is evaluated. The effect of pH, response time, selectivity, and sensitivity is investigated. Under the optimized conditions, a simple and rapid method for the determination of clenbuterol from milk sample is established by immuno-potentiometric sensor. The detection limit has found to be 0.87 × 10-9 mmol L-1 for this immuno-potentiometric sensor. This immuno-potentiometric sensor has optimum pH at 7.0, a wide linear response (1.0 × 10-2 to 1.0 × 10-9 mmol L-1 ), rapid response time (2 Min) and 36 weeks operational lifetime.

Potentiometric sensor fabrication having 2D sarcosine memories and analytical features.

In this study, a simple, rapid and sensitive method based on novel molecular imprinted polymeric sensor has been developed and validated for the determination of prostate cancer metabolite biomarker. The molecularly imprinted polymer (MIP) has been synthesized by emulsion polymerization, using sarcosine as template molecule, methacryloylamido histidine (MAH) as functional monomer and ethylene glycol dimethacrylate (EDMA) as cross-linking agent. The performance of the developed sarcosine sensor has been evaluated, and the results have indicated that a sensitive potentiometric sensor has been fabricated. The sarcosine sensor has showed high-selectivity, shorter response time (<2min), wider linear range (10(-2)-10(-6)mM), lower detection limit (1.35×10(-7)mM), and satisfactory long-term stability (>5.5months).

Ligand exchange based paraoxon imprinted QCM sensor.

In the present work, a paraoxon imprinted QCM sensor has been developed for the determination of paraoxon based on the modification of paraoxon imprinted film onto a quartz crystal combining the advantages of high selectivity of the piezoelectric microgravimetry using MIP film technique and high sensitivity of QCM detection. The paraoxon selective memories have formed on QCM electrode surface by using a new metal-chelate interaction based on pre-organized monomer and the paraoxon recognition activity of these molecular memories was investigated. Molecular imprinted polymer (MIP) film for the detection of paraoxon was developed and the analytical performance of paraoxon imprinted sensor was studied. The molecular imprinted polymer were characterized by FTIR measurements. Paraoxon imprinted sensor was characterized with AFM and ellipsometer. The study also includes the measurement of binding interaction of paraoxon imprinted quartz crystal microbalance (QCM) sensor, selectivity experiments and analytical performance of QCM electrode. The detection limit and the affinity constant (K(affinity)) were found to be 0.06 µM and 2.25 × 10(4) M(-1) for paraoxon [MAAP-Cu(II)-paraoxon] based thin film, respectively. Also, it has been observed that the selectivity of the prepared paraoxon imprinted sensor is high compared to a similar chemical structure which is parathion.

Preconcentration of phosphate ion onto ion-imprinted polymer.

In this study, selective separation and preconcentration of phosphate ions on the phosphate-imprinted chitosan-succinate beads have investigated. Chitosan-succinate, phosphate, epichlorohydrin were used as the complexing monomer, template and crosslinking agent, respectively. In the first step, chitosan was modified with succinic anhydrides and complex formation occurred between carboxylic acid functional groups and iron(III) ions. Secondly, Fe(III)-chitosan-succinate particles were reacted with phosphate ions. Afterwards, particles were crosslinked with epichlorohydrin and the template (phosphate ions) was removed using 1M KOH solution. Selective cavity for the phosphate ion was obtained in the phosphate-imprinted metal-chelate polymer. These phosphate-imprinted metal-chelate polymer was used in the adsorption-desorption process. The adsorption process was fast and equilibrium was reached around 30 min. The adsorption behaviour of this system was described approximately by the Langmuir equation. Percent extraction, distribution ratio and selectivity coefficients of phosphate and other ions using non-imprinted and phosphate-imprinted polymer were also determined and comparison of these data was reported.