Electrochemically-Preadsorbed Collagen Promotes Adult Human Mesenchymal Stem Cell Adhesion on Carbon Nanostructured Substrates

The effect of electric potential on the adsorption of collagen type I onto optically transparent carbon electrodes (OTCE) and its mediation on subsequent adhesion of adult, human, mesenchymal stem cells (hMSCs) is described. Adsorption was investigated as a function of the protein concentration and applied potential. The resulting substrate surfaces were characterized using spectroscopic ellipsometry (SE), atomic force microscopy (AFM), and cyclic voltammetry (CV). While the higher applied potential and protein concentration, the higher the adsorbed amount, the application of potential values higher than +800 mV resulted in the oxidation of the adsorbed protein. Subsequent adhesion of hMSCs on the substrates under standard cell culture conditions was also affected by the potential applied and when the collagen type I was oxidized (under applied potential \u3e +800 mV), hMSCs adhesion was decreased. These results provide the first correlation between the effects of electric potential on protein adsorption and subsequent modulation of anchorage-dependent cell adhesion

Development and Application of Cu-Modified Carbon Electrodes from Pyrolyzed Paper Strips

A one-step approach for the synthesis and integration of copper nanoparticles (CuNPs) onto paper-based carbon electrodes is herein reported. The method is based on the pyrolysis (1000 ºC under a mixture of 95% Ar / 5% H2 for 1 hour) of paper strips modified with a saturated solution of CuSO4 and yields to the formation of abundant CuNPs on the surface of carbonized cellulose fibers. The resulting substrates were characterized by a combination of scanning electron microscopy, EDX, Raman spectroscopy as well as electrical and electrochemical techniques. Their potential application, as working electrodes for non-enzymatic amperometric determination of glucose, was then demonstrated (linear response up to 3 μM and a sensitivity of 460 ± 8 μA∙cm-2∙mM-1). Besides being a simple and inexpensive process for the development of electrochemically active substrates, this approach opens new possibilities for the in-situ synthesis of metallic nanoparticles without the traditional requirements of solutions and adjuvants

Electrochemically Preadsorbed Collagen Promotes Adult Human Mesenchymal Stem Cell Adhesion

The present article reports on the effect of electric potential on the adsorption of collagen type I (the most abundant component of the organic phase of bone) onto optically transparent carbon electrodes (OTCE) and its mediation on subsequent adhesion of adult, human, mesenchymal stem cells (hMSCs). For this purpose, adsorption of collagen type I was investigated as a function of the protein concentration (0.01, 0.1, and 0.25 mg/mL) and applied potential (open circuit potential [OCP; control], +400, +800, and +1500 mV). The resulting substrate surfaces were characterized using spectroscopic ellipsometry, atomic force microscopy, and cyclic voltammetry. Adsorption of collagen type I onto OTCE was affected by the potential applied to the sorbent surface and the concentration of protein. The higher the applied potential and protein concentration, the higher the adsorbed amount (Γcollagen). It was also observed that the application of potential values higher than +800 mV resulted in the oxidation of the adsorbed protein. Subsequent adhesion of hMSCs on the OTCEs (precoated with the collagen type I films) under standard cell culture conditions for 2 h was affected by the extent of collagen preadsorbed onto the OTCE substrates. Specifically, enhanced hMSCs adhesion was observed when the Γcollagen was the highest. When the collagen type I was oxidized (under applied potential equal to +1500 mV), however, hMSCs adhesion was decreased. These results provide the first correlation between the effects of electric potential on protein adsorption and subsequent modulation of anchorage-dependent cell adhesion.Fil: Benavidez, Tomás Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Clemson University; Estados UnidosFil: Wechsler, Marissa E.. University of Texas; Estados UnidosFil: Farrer, Madeleine M.. University of Texas; Estados UnidosFil: Bizios, Rena. University of Texas; Estados UnidosFil: Garcia, Carlos D.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Clemson University; Estados Unido

Analysis of penicillamine using Cu-modified graphene quantum dots synthesized from uric acid as single precursor

A simple methodology was developed to quantify penicillamine (PA) in pharmaceutical samples, using the selective interaction of the drug with Cu-modified graphene quantum dots (Cu-GQDs). The proposed strategy combines the advantages of carbon dots (over other nanoparticles) with the high affinity of PA for the proposed Cu-GQDs, resulting in a significant and selective quenching effect. Under the optimum conditions for the interaction, a linear response (in the 0.10–7.50 µmol/L PA concentration range) was observed. The highly fluorescent GQDs used were synthesized using uric acid as single precursor and then characterized by high resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence, and absorption spectroscopy. The proposed methodology could also be extended to other compounds, further expanding the applicability of GQDs

Adsorption of soft and hard proteins onto OTCEs under the influence of an external electric field

The adsorption behavior of hard and soft proteins under the effect of an external electric field was investigated by a combination of spectroscopic ellipsometry and molecular dynamics (MD) simulations. Optically transparent carbon electrodes (OTCE) were used as conductive, sorbent substrates. Lysozyme (LSZ) and ribonuclease A (RNase A) were selected as representative hard proteins, whereas myoglobin (Mb), α-lactalbumin (α-LAC), bovine serum albumin (BSA), glucose oxidase (GOx), and immunoglobulin G (IgG) were selected to represent soft proteins. In line with recent publications from our group, the experimental results revealed that while the adsorption of all investigated proteins can be enhanced by the potential applied to the electrode, the effect is more pronounced for hard proteins. In contrast with the incomplete monolayers formed at open-circuit potential, the application of +800 mV to the sorbent surface induced the formation of multiple layers of protein. These results suggest that this effect can be related to the intrinsic polarizability of the protein (induction of dipoles), the resulting surface accessible solvent area (SASA), and structural rearrangements induced upon the incorporation on the protein layer. The described experiments are critical to understand the relationship between the structure of proteins and their tendency to form (under electric stimulation) layers with thicknesses that greatly surpass those obtained at open-circuit conditions.Fil: Benavidez, Tomás Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. University of Texas; Estados UnidosFil: Torrente, Daniel. University of Texas; Estados UnidosFil: Marucho, Marcelo. University of Texas; Estados UnidosFil: Garcia, Carlos D. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. University of Texas; Estados Unido