Growth of gold nanorods (AuNRs) by photochemical reduction of HAuCl4 in a micelle solution of hex... more Growth of gold nanorods (AuNRs) by photochemical reduction of HAuCl4 in a micelle solution of hexadecyltrimethylammonium bromide (CTAB) and tetraoctylammonium bromide (TOAB) is studied. The effects of 300 and 254 nm UV light sources and their photon flux on the anisotropic growth of gold nanoparticles are investigated by controlling duration of irradiation and the number of lamps within a photochemical reactor. The resulting AuNRs were characterized by absorption spectroscopy, FTIR, and TEM. Experimental results indicate that a higher density of longer colloidal AuNRs form by increasing the number of incident photons (lamps) at 300 nm while the 254 nm lights produce a lower yield of shorter AuNRs. The yield of AuNRs also depends on the duration of irradiation which was found to be 6.00 h for 300 nm and 5.00 h for 254 nm radiation. Acetone is found to play a major role in the synthesis of AuNRs. Two mechanisms are proposed for the synthesis of Au nanoparticles in the presence and absence of acetone. Irradiation of samples for an excess time produces a lower concentration of AuNRs and a higher yield of spherical particles. This effect is attributed to atom-by-atom dissolution of AuNRs into Au-spherical particles.
Resumen.-OBJETIVOS: La tendencia a la diseminación del cáncer de próstata es sobre todo a los gan... more Resumen.-OBJETIVOS: La tendencia a la diseminación del cáncer de próstata es sobre todo a los ganglios linfáticos regionales y hueso, y en una menor proporción a pulmón, hígado y cerebro. El hallazgo de metástasis en otras localizaciones es un hecho excepcional.
A system is proposed to convert ambient mechanical vibration into electrical energy for use in po... more A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low power electronic systems. The energy is transduced through the use of a variable capacitor. Using microelectromechanical systems (MEMS) technology, such a device has been designed for the system. A low-power controller IC has been fabricated in a 0.6-m CMOS process and has been tested and measured for losses. Based on the tests, the system is expected to produce 8 W of usable power. In addition to the fabricated programmable controller, an ultra low-power delay locked loop (DLL)-based system capable of autonomously achieving a steady-state lock to the vibration frequency is described.
... Oscar R. Miranda, Norman R. Dollahon, and Temer S. Ahmadi*. Department of Chemistry, Villan... more ... Oscar R. Miranda, Norman R. Dollahon, and Temer S. Ahmadi*. Department of Chemistry, Villanova University, Villanova, Pennsylvania 19085. Crystal Growth & Design , 2006, 6 (12), pp 27472753. DOI: 10.1021/cg060455l. ...
Controlling the firing rate of a neuron is useful for experiments where you would like to see how... more Controlling the firing rate of a neuron is useful for experiments where you would like to see how a small perturbation to the neuron deviates it from its normal period. This is used to characterize phase response curves (PRCs). PRCs can be used to predict how networks of neurons will synchronize, which help in understanding dynamical diseases as epilepsy.
El frecuente uso de la punción aspiración con aguja fina (PAAF) como técnica diagnóstica, aplicab... more El frecuente uso de la punción aspiración con aguja fina (PAAF) como técnica diagnóstica, aplicable al estudio de tumores accesibles tanto radiológicamente como por simple palpación, obliga a los patólogos a un conocimiento cada vez más profundo del aspecto citológico de las lesiones, tanto de las más frecuentes y elementales, como de aquellas que se observan rara vez en la diaria labor asistencial.
There is a direct correlation between protein levels and disease states in human serum, which mak... more There is a direct correlation between protein levels and disease states in human serum, which makes it an attractive target for sensors and diagnostics. However, this is challenging because serum features more than 20,000 proteins, with an overall protein content greater than 1 mM. Here we report a sensor based on a hybrid synthetic-biomolecule that uses arrays of green fluorescent protein and nanoparticles to detect proteins at biorelevant concentrations in both buffer and human serum. Distinct and reproducible fluorescence-response patterns were obtained from five serum proteins (human serum albumin, immunoglobulin G, transferrin, fibrinogen and a-antitrypsin), both in buffer and when spiked into human serum. Using linear discriminant analysis we identified these proteins with an identification accuracy of 100% in buffer and 97% in human serum. The arrays were also able to discriminate between different concentrations of the same protein, as well as a mixture of different proteins in human serum.
We have developed an enzyme-nanoparticle sensor array where the sensitivity is amplified through ... more We have developed an enzyme-nanoparticle sensor array where the sensitivity is amplified through enzymatic catalysis. In this approach cationic gold nanoparticles are electrostatically bound to an enzyme (β-galactosidase, β-Gal), inhibiting enzyme activity. Analyte proteins release the β-Gal, restoring activity and providing an amplified readout of the binding event. Using this strategy we have been able to identify proteins in buffer at a concentration of 1 nM, substantially lower than current strategies for array-based protein sensing. Moreover, we have obtained identical sensitivity in studies where the proteins are spiked into the complex protein matrix provided by desalted human urine (~1.5 µM total protein; spiked protein concentrations were 0.067% of the overall protein concentration), demonstrating the potential of the method for diagnostic applications.
A sensor array containing six non-covalent gold nanoparticle-fluorescent polymer conjugates has b... more A sensor array containing six non-covalent gold nanoparticle-fluorescent polymer conjugates has been created to detect and identify protein targets. The polymer fluorescence is quenched by gold nanoparticles. The presence of proteins disrupts the nanoparticle-polymer interaction, producing distinct fluorescence response patterns. These patterns are highly repeatable and are characteristic for individual proteins.
Growth of gold nanorods (AuNRs) by photochemical reduction of HAuCl4 in a micelle solution of hex... more Growth of gold nanorods (AuNRs) by photochemical reduction of HAuCl4 in a micelle solution of hexadecyltrimethylammonium bromide (CTAB) and tetraoctylammonium bromide (TOAB) is studied. The effects of 300 and 254 nm UV light sources and their photon flux on the anisotropic growth of gold nanoparticles are investigated by controlling duration of irradiation and the number of lamps within a photochemical reactor. The resulting AuNRs were characterized by absorption spectroscopy, FTIR, and TEM. Experimental results indicate that a higher density of longer colloidal AuNRs form by increasing the number of incident photons (lamps) at 300 nm while the 254 nm lights produce a lower yield of shorter AuNRs. The yield of AuNRs also depends on the duration of irradiation which was found to be 6.00 h for 300 nm and 5.00 h for 254 nm radiation. Acetone is found to play a major role in the synthesis of AuNRs. Two mechanisms are proposed for the synthesis of Au nanoparticles in the presence and absence of acetone. Irradiation of samples for an excess time produces a lower concentration of AuNRs and a higher yield of spherical particles. This effect is attributed to atom-by-atom dissolution of AuNRs into Au-spherical particles.
Resumen.-OBJETIVOS: La tendencia a la diseminación del cáncer de próstata es sobre todo a los gan... more Resumen.-OBJETIVOS: La tendencia a la diseminación del cáncer de próstata es sobre todo a los ganglios linfáticos regionales y hueso, y en una menor proporción a pulmón, hígado y cerebro. El hallazgo de metástasis en otras localizaciones es un hecho excepcional.
A system is proposed to convert ambient mechanical vibration into electrical energy for use in po... more A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low power electronic systems. The energy is transduced through the use of a variable capacitor. Using microelectromechanical systems (MEMS) technology, such a device has been designed for the system. A low-power controller IC has been fabricated in a 0.6-m CMOS process and has been tested and measured for losses. Based on the tests, the system is expected to produce 8 W of usable power. In addition to the fabricated programmable controller, an ultra low-power delay locked loop (DLL)-based system capable of autonomously achieving a steady-state lock to the vibration frequency is described.
... Oscar R. Miranda, Norman R. Dollahon, and Temer S. Ahmadi*. Department of Chemistry, Villan... more ... Oscar R. Miranda, Norman R. Dollahon, and Temer S. Ahmadi*. Department of Chemistry, Villanova University, Villanova, Pennsylvania 19085. Crystal Growth & Design , 2006, 6 (12), pp 27472753. DOI: 10.1021/cg060455l. ...
Controlling the firing rate of a neuron is useful for experiments where you would like to see how... more Controlling the firing rate of a neuron is useful for experiments where you would like to see how a small perturbation to the neuron deviates it from its normal period. This is used to characterize phase response curves (PRCs). PRCs can be used to predict how networks of neurons will synchronize, which help in understanding dynamical diseases as epilepsy.
El frecuente uso de la punción aspiración con aguja fina (PAAF) como técnica diagnóstica, aplicab... more El frecuente uso de la punción aspiración con aguja fina (PAAF) como técnica diagnóstica, aplicable al estudio de tumores accesibles tanto radiológicamente como por simple palpación, obliga a los patólogos a un conocimiento cada vez más profundo del aspecto citológico de las lesiones, tanto de las más frecuentes y elementales, como de aquellas que se observan rara vez en la diaria labor asistencial.
There is a direct correlation between protein levels and disease states in human serum, which mak... more There is a direct correlation between protein levels and disease states in human serum, which makes it an attractive target for sensors and diagnostics. However, this is challenging because serum features more than 20,000 proteins, with an overall protein content greater than 1 mM. Here we report a sensor based on a hybrid synthetic-biomolecule that uses arrays of green fluorescent protein and nanoparticles to detect proteins at biorelevant concentrations in both buffer and human serum. Distinct and reproducible fluorescence-response patterns were obtained from five serum proteins (human serum albumin, immunoglobulin G, transferrin, fibrinogen and a-antitrypsin), both in buffer and when spiked into human serum. Using linear discriminant analysis we identified these proteins with an identification accuracy of 100% in buffer and 97% in human serum. The arrays were also able to discriminate between different concentrations of the same protein, as well as a mixture of different proteins in human serum.
We have developed an enzyme-nanoparticle sensor array where the sensitivity is amplified through ... more We have developed an enzyme-nanoparticle sensor array where the sensitivity is amplified through enzymatic catalysis. In this approach cationic gold nanoparticles are electrostatically bound to an enzyme (β-galactosidase, β-Gal), inhibiting enzyme activity. Analyte proteins release the β-Gal, restoring activity and providing an amplified readout of the binding event. Using this strategy we have been able to identify proteins in buffer at a concentration of 1 nM, substantially lower than current strategies for array-based protein sensing. Moreover, we have obtained identical sensitivity in studies where the proteins are spiked into the complex protein matrix provided by desalted human urine (~1.5 µM total protein; spiked protein concentrations were 0.067% of the overall protein concentration), demonstrating the potential of the method for diagnostic applications.
A sensor array containing six non-covalent gold nanoparticle-fluorescent polymer conjugates has b... more A sensor array containing six non-covalent gold nanoparticle-fluorescent polymer conjugates has been created to detect and identify protein targets. The polymer fluorescence is quenched by gold nanoparticles. The presence of proteins disrupts the nanoparticle-polymer interaction, producing distinct fluorescence response patterns. These patterns are highly repeatable and are characteristic for individual proteins.
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