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Papers by Colette McDonagh
Analytical Chemistry, 2014
ABSTRACT Optical chemical sensors are considered to be 'senses of electronics' an... more ABSTRACT Optical chemical sensors are considered to be 'senses of electronics' and 'eyes and ears capable of seeing and hearing beyond the human perception'.1 A widely used Cambridge interpretation of a chemical sensor states that 'a chemical sensor is a miniaturised analytical device which can deliver real-time, on-line information on the presence of specific compounds or ions in complex samples'. 2.
Journal of Materials Chemistry, 2012
Sensors and Actuators B: Chemical, 2009
2011 IEEE SENSORS Proceedings, 2011
ABSTRACT We present luminescence-based nanosensors for oxygen (O2) and calcium ions (Ca2+) sensin... more ABSTRACT We present luminescence-based nanosensors for oxygen (O2) and calcium ions (Ca2+) sensing in the cellular environment. A novel ratiometric Ca2+-sensitive nanoparticle (NP) consisting of a silica core coated with a shell of dextran was synthesised. A rhodamine-based reference dye was covalently bound to the silica core while the dextran shell was labelled with the Ca2+-sensitive probe Fluo-4. The nanoparticles have an average hydrodynamic diameter of 95 nm, good colloidal stability and show a 2.9-fold increase in fluorescence intensity upon binding to Ca2+ ions. The determined dissociation constant of Kd ≈ 520 nM is well suited for measurements in the physiological range. The oxygen-sensitive optical probe is the ruthenium complex [Ru(II)-tris(4,7-diphenyl-1,10-phenanthroline), which was encapsulated in silica NPs which were synthesised using the Stöber sol-gel process. The oxygen sensitivity of the nanoparticles was measured and a calibration curve established. In addition preliminary measurements have been carried out on the introduction of the NPs into macrophages.
2011 IEEE SENSORS Proceedings, 2011
ABSTRACT We report on high performance ratiometric fluorescence-based pH and dissolved carbon dio... more ABSTRACT We report on high performance ratiometric fluorescence-based pH and dissolved carbon dioxide (dCO2) sensors for use in bioprocess and environmental monitoring applications, respectively. Novel hybrid sol-gel-based sensor materials have been developed and successfully used as host matrices in pH and dCO2 sensing. These sensors are easy to prepare and miniaturise, low-cost in terms of fabrication, are mass-producible and when the combination of key performance parameters is considered, compare very well to similar sensor systems which have been reported in the literature in terms of resolution, stability and leaching characteristics. Both pH and dCO2 sensor films can be interrogated with a robust, ratiometric optical probe that combines effective fluorescence excitation and detection and thus facilitates the production of a highly-sensitive sensor system using low-cost optoelectronic components. In the probe configuration both LEDs are operated simultaneously, which represents a significant improvement over existing ratiometric systems where the light sources must by operated sequentially.
Journal of Biomedical Optics, 2008
Surface plasmon-coupled emission SPCE is a phenom- enon whereby the light emitted from a fluoresc... more Surface plasmon-coupled emission SPCE is a phenom- enon whereby the light emitted from a fluorescent molecule can couple into the surface plasmon of an adjacent metal layer, resulting in highly directional emission in the region of the surface plasmon resonance SPR angle. In addition to high directionality of emission, SPCE has the added advantage of surface selectivity in that the
Sensors and Actuators B-chemical - SENSOR ACTUATOR B-CHEM, 2001
The design and performance of a ruggedised dissolved oxygen (DO) probe, which is based on phase f... more The design and performance of a ruggedised dissolved oxygen (DO) probe, which is based on phase fluorometric detection of the quenched fluorescence of an oxygen-sensitive ruthenium complex, is reported. The complex is entrapped in a porous hydrophobic sol–gel matrix that has been optimised for this application. The LED excitation and photodiode detection are employed in a dipstick probe configuration, with the oxygen-sensitive film coated on a disposable PMMA disc, which in turn is designed to guide light into the film by total internal reflection. A key element of the design is the common mode rejection of phase between the signal and reference channels, requiring careful selection of the relevant optoelectronic components. The advantages of the phase fluorometric approach over intensity measurement are highlighted. The phase detection electronics exhibits excellent long-term stability with a temperature coefficient of 0.00087. The sensor response exhibits excellent signal-to-noise...
A range of both sol-gel and polymer derived sensor films have been developed for optical oxygen a... more A range of both sol-gel and polymer derived sensor films have been developed for optical oxygen and pH sensing. Oxygen sensing is based on the luminescence quenching of the ruthenium complex (Ru(II)-tris( 4,7-diphenyl-1,10-phenanthroline))dichloride, ((Ru(dpp)3) 2+ ), which is entrapped in the sol-gel matrix. The oxygen-dependent luminescence is detected using the principle of phase fluorometry, which facilitates indirect monitoring of the
Coordination Chemistry Reviews, 1999
Plasmonics, 2006
Abstract This paper reports on the enhancement of fluorescence that can result from the proximity... more Abstract This paper reports on the enhancement of fluorescence that can result from the proximity of fluorophores to metallic nanoparticles (NPs). This plasmonic enhancement, which is a result of the localized surface plasmon resonance at the metal surface, can be ...
The Journal of Physical Chemistry C, 2009
Journal of Solid State Chemistry - J SOLID STATE CHEM, 2011
Recently, multifunctional silica nanoparticles have been investigated extensively for their poten... more Recently, multifunctional silica nanoparticles have been investigated extensively for their potential use in biomedical applications. We have prepared sub-micron monodisperse and stable multifunctional mesoporous silica particles with a high level of magnetization and fluorescence in the near infrared region using an one-pot synthesis technique. Commercial magnetite nanocrystals and a conjugated-NIR-dye were incorporated inside the particles during the silica condensation reaction. The particles were then coated with polyethyleneglycol to stop aggregation. X-ray diffraction, N2 adsorption analysis, TEM, fluorescence and absorbance measurements were used to structurally characterize the particles. These mesoporous silica spheres have a large surface area (1978m2/g) with 3.40nm pore diameter and a high fluorescence in the near infrared region at λ=700nm. To explore the potential of these particles for drug delivery applications, the pore accessibility to hydrophobic drugs was simulate...
Electronics Letters, 1994
... 1, is obvious. The bimolecu-ELECTRONICS LElTERS 26th May 1994 Vol. 30 ... 8 IEE 1994 Electron... more ... 1, is obvious. The bimolecu-ELECTRONICS LElTERS 26th May 1994 Vol. 30 ... 8 IEE 1994 Electronics Letters Online No: 19940578 BD Mac Craith, G. O'Keeffe, C. McDonagh and AK McEvoy (School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland) ...
Analytical Chemistry, 2014
ABSTRACT Optical chemical sensors are considered to be 'senses of electronics' an... more ABSTRACT Optical chemical sensors are considered to be 'senses of electronics' and 'eyes and ears capable of seeing and hearing beyond the human perception'.1 A widely used Cambridge interpretation of a chemical sensor states that 'a chemical sensor is a miniaturised analytical device which can deliver real-time, on-line information on the presence of specific compounds or ions in complex samples'. 2.
Journal of Materials Chemistry, 2012
Sensors and Actuators B: Chemical, 2009
2011 IEEE SENSORS Proceedings, 2011
ABSTRACT We present luminescence-based nanosensors for oxygen (O2) and calcium ions (Ca2+) sensin... more ABSTRACT We present luminescence-based nanosensors for oxygen (O2) and calcium ions (Ca2+) sensing in the cellular environment. A novel ratiometric Ca2+-sensitive nanoparticle (NP) consisting of a silica core coated with a shell of dextran was synthesised. A rhodamine-based reference dye was covalently bound to the silica core while the dextran shell was labelled with the Ca2+-sensitive probe Fluo-4. The nanoparticles have an average hydrodynamic diameter of 95 nm, good colloidal stability and show a 2.9-fold increase in fluorescence intensity upon binding to Ca2+ ions. The determined dissociation constant of Kd ≈ 520 nM is well suited for measurements in the physiological range. The oxygen-sensitive optical probe is the ruthenium complex [Ru(II)-tris(4,7-diphenyl-1,10-phenanthroline), which was encapsulated in silica NPs which were synthesised using the Stöber sol-gel process. The oxygen sensitivity of the nanoparticles was measured and a calibration curve established. In addition preliminary measurements have been carried out on the introduction of the NPs into macrophages.
2011 IEEE SENSORS Proceedings, 2011
ABSTRACT We report on high performance ratiometric fluorescence-based pH and dissolved carbon dio... more ABSTRACT We report on high performance ratiometric fluorescence-based pH and dissolved carbon dioxide (dCO2) sensors for use in bioprocess and environmental monitoring applications, respectively. Novel hybrid sol-gel-based sensor materials have been developed and successfully used as host matrices in pH and dCO2 sensing. These sensors are easy to prepare and miniaturise, low-cost in terms of fabrication, are mass-producible and when the combination of key performance parameters is considered, compare very well to similar sensor systems which have been reported in the literature in terms of resolution, stability and leaching characteristics. Both pH and dCO2 sensor films can be interrogated with a robust, ratiometric optical probe that combines effective fluorescence excitation and detection and thus facilitates the production of a highly-sensitive sensor system using low-cost optoelectronic components. In the probe configuration both LEDs are operated simultaneously, which represents a significant improvement over existing ratiometric systems where the light sources must by operated sequentially.
Journal of Biomedical Optics, 2008
Surface plasmon-coupled emission SPCE is a phenom- enon whereby the light emitted from a fluoresc... more Surface plasmon-coupled emission SPCE is a phenom- enon whereby the light emitted from a fluorescent molecule can couple into the surface plasmon of an adjacent metal layer, resulting in highly directional emission in the region of the surface plasmon resonance SPR angle. In addition to high directionality of emission, SPCE has the added advantage of surface selectivity in that the
Sensors and Actuators B-chemical - SENSOR ACTUATOR B-CHEM, 2001
The design and performance of a ruggedised dissolved oxygen (DO) probe, which is based on phase f... more The design and performance of a ruggedised dissolved oxygen (DO) probe, which is based on phase fluorometric detection of the quenched fluorescence of an oxygen-sensitive ruthenium complex, is reported. The complex is entrapped in a porous hydrophobic sol–gel matrix that has been optimised for this application. The LED excitation and photodiode detection are employed in a dipstick probe configuration, with the oxygen-sensitive film coated on a disposable PMMA disc, which in turn is designed to guide light into the film by total internal reflection. A key element of the design is the common mode rejection of phase between the signal and reference channels, requiring careful selection of the relevant optoelectronic components. The advantages of the phase fluorometric approach over intensity measurement are highlighted. The phase detection electronics exhibits excellent long-term stability with a temperature coefficient of 0.00087. The sensor response exhibits excellent signal-to-noise...
A range of both sol-gel and polymer derived sensor films have been developed for optical oxygen a... more A range of both sol-gel and polymer derived sensor films have been developed for optical oxygen and pH sensing. Oxygen sensing is based on the luminescence quenching of the ruthenium complex (Ru(II)-tris( 4,7-diphenyl-1,10-phenanthroline))dichloride, ((Ru(dpp)3) 2+ ), which is entrapped in the sol-gel matrix. The oxygen-dependent luminescence is detected using the principle of phase fluorometry, which facilitates indirect monitoring of the
Coordination Chemistry Reviews, 1999
Plasmonics, 2006
Abstract This paper reports on the enhancement of fluorescence that can result from the proximity... more Abstract This paper reports on the enhancement of fluorescence that can result from the proximity of fluorophores to metallic nanoparticles (NPs). This plasmonic enhancement, which is a result of the localized surface plasmon resonance at the metal surface, can be ...
The Journal of Physical Chemistry C, 2009
Journal of Solid State Chemistry - J SOLID STATE CHEM, 2011
Recently, multifunctional silica nanoparticles have been investigated extensively for their poten... more Recently, multifunctional silica nanoparticles have been investigated extensively for their potential use in biomedical applications. We have prepared sub-micron monodisperse and stable multifunctional mesoporous silica particles with a high level of magnetization and fluorescence in the near infrared region using an one-pot synthesis technique. Commercial magnetite nanocrystals and a conjugated-NIR-dye were incorporated inside the particles during the silica condensation reaction. The particles were then coated with polyethyleneglycol to stop aggregation. X-ray diffraction, N2 adsorption analysis, TEM, fluorescence and absorbance measurements were used to structurally characterize the particles. These mesoporous silica spheres have a large surface area (1978m2/g) with 3.40nm pore diameter and a high fluorescence in the near infrared region at λ=700nm. To explore the potential of these particles for drug delivery applications, the pore accessibility to hydrophobic drugs was simulate...
Electronics Letters, 1994
... 1, is obvious. The bimolecu-ELECTRONICS LElTERS 26th May 1994 Vol. 30 ... 8 IEE 1994 Electron... more ... 1, is obvious. The bimolecu-ELECTRONICS LElTERS 26th May 1994 Vol. 30 ... 8 IEE 1994 Electronics Letters Online No: 19940578 BD Mac Craith, G. O'Keeffe, C. McDonagh and AK McEvoy (School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland) ...