Current topics in medicinal chemistry, Jan 4, 2016
Tuberculosis, one of the oldest diseases affecting human beings, is still considered as a world p... more Tuberculosis, one of the oldest diseases affecting human beings, is still considered as a world public health problem by the World Health Organization. Therefore, there is a need for new and more powerful analytical methods for early illness diagnosis. With this idea in mind, the development of a High Fundamental Frequency (HFF) piezoelectric immunosensor for the sensitive detection of tuberculosis was undertaken. A 38 kDa protein secreted by Mycobacterium tuberculosis was first selected as the target biomarker. Then, specific monoclonal antibodies (MAbs) were obtained. Myc-31 MAb, which showed the highest affinity to the analyte, was employed to set up a reference enzyme-linked immunosorbent assay (ELISA) with a limit of detection of 14 ng mL-1 of 38 kDa antigen. For the development of the HFF piezoelectric immunosensor, 100 MHz quartz crystals were used as transducer elements. The gold electrode surface was functionalized by covalent immobilization of the target biomarker through ...
Acoustic wave resonators have become suitable devices for a broad range of sensing applications d... more Acoustic wave resonators have become suitable devices for a broad range of sensing applications due to their sensitivity, low cost, and integration capability, which are all factors that meet the requirements for the resonators to be used as sensing elements for portable point of care (PoC) platforms. In this work, the design, characterization, and validation of a 150 MHz high fundamental frequency quartz crystal microbalance (HFF-QCM) sensor for bio-sensing applications are introduced. Finite element method (FEM) simulations of the proposed design are in good agreement with the electrical characterization of the manufactured resonators. The sensor is also validated for bio-sensing applications. For this purpose, a specific sensor cell was designed and manufactured that addresses the critical requirements associated with this type of sensor and application. Due to the small sensing area and the sensor's fragility, these requirements include a low-volume flow chamber in the nanol...
A deep analysis of the problem associated with oscillators as interface circuits for quartz-cryst... more A deep analysis of the problem associated with oscillators as interface circuits for quartz-crystal-microbalance sensors, reveals that the so-called static capacitance of the sensor is one of the elements that makes the use of oscillators more critical for sensors applications. A phase-locked-loop based circuit specifically designed for compensating the parallel capacitance effects in quartz crystal resonator sensors is presented. This
An extended Butterworth-Van Dyke (EBVD) model to characterize a thickness-shear mode quartz cryst... more An extended Butterworth-Van Dyke (EBVD) model to characterize a thickness-shear mode quartz crystal resonator in a semi-infinite viscoelastic medium is derived by means of analysis of the lumped elements model described by Cernosek et al. [R. W. Cernosek, S. J. Martin, A. R. Hillman, and H. L. Bandey, IEEE Trans. Ultrason. Ferroelectr. Freq. Control 45, 1399 (1998)]. The EBVD model
A new electronic design for continuous motional series resonant frequency monitoring of loaded qu... more A new electronic design for continuous motional series resonant frequency monitoring of loaded quartz crystal resonators is presented. Using this circuit, a low-cost method for a simple determination of equivalent circuit parameters of quartz crystal resonators is described. Measurements made with the proposed system on typical AT cut quartz crystals are in good agreement with those of an Impedance Analyzer.
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000
An extended Butterworth-Van Dyke (EBVD) model with frequency-independent parameters for the chara... more An extended Butterworth-Van Dyke (EBVD) model with frequency-independent parameters for the characterization of a resonant compound formed by a quartz crystal in contact with a finite viscoelastic layer contacting a semi-infinite viscoelastic medium is extracted by analysis of the lumped element model. The formulation of the EBVD model is compared with the complete expression of the electrical admittance of the loaded quartz derived from the transmission line model (TLM). Relative deviations between them do not exceed 3% around 1% bandwidth near resonance. An extended Martin & Granstaff's model and an explicit expression for the frequency shift that supposes an extension of Kanazawa's model for viscoelastic media are obtained. An analysis of the errors associated with the extraction of shear parameters of the coating for different materials prove that, to obtain an error less than 5% in the shear parameters determination, the viscoelastic contribution, defined as the relative error in the thickness computed from the frequency shift by Sauerbrey equation, must be greater than a limit that depends on Q, which is defined as the ratio of the shear storage modulus (G') to shear loss modulus (G"). In the materials studied, polymers in the transition range or in the rubbery state with Q = 1 and 10, the viscoelastic contribution must be higher than 15% and 50%, respectively, for a 5% limit error in the shear parameters extraction. A criterion for a practical determination of the appropriate viscoelastic regimes is indicated.
IEEE International Frequency Control Symposium, 2011
Quartz crystal microbalance (QCM) technique is widely used in in-liquid biochemical applications.... more Quartz crystal microbalance (QCM) technique is widely used in in-liquid biochemical applications. The main challenges remain on the improvement of sensitivity and limit of detection, as well as multianalysis capabilities and reliability. The improvement of sensitivity has been addressed in the last decades by increasing the sensor fundamental frequency; following the increment of the frequency/mass sensitivity with the square of
Medicina oral, patología oral y cirugía bucal, 2009
Sjögren's syndrome is one of the most frequent autoimmune diseases. It is a chronic and syste... more Sjögren's syndrome is one of the most frequent autoimmune diseases. It is a chronic and systemic disorder predominantly found in women, and is characterized by the appearance of a lymphocytic inflammatory infiltrate, with dryness of the oral cavity and eyes, secondary to involvement of the salivary and lacrimal glands. The underlying causal mechanism involves a number of factors and has not been clearly established, though an autoimmune response is known to be triggered, with the accumulation of immune complexes in the gland acini that interfere with gland function. In the oral cavity, xerostomia or hyposialia is the most disabling manifestation for patients, and is accompanied by rapidly progressing caries, candidiasis and an important worsening of buccodental health. The most important complication is a 44-fold increase in the risk of developing non-Hodgkin lymphoma, compared with the general population. The treatment of Sjögren's syndrome is limited to symptomatic managem...
Oral anticoagulants (OACs) antagonizing vitamin K - fundamentally sodium warfarin and acenocoumar... more Oral anticoagulants (OACs) antagonizing vitamin K - fundamentally sodium warfarin and acenocoumarol - are wi- dely used for preventing arterial thromboembolism in patients with atrial fibrillation and/or heart valve prostheses, and for the treatment and prevention of deep venous thrombosis and pulmonary embolism. The handling of these drugs requires correct monitorization and dose adjustment to obtain the desired therapeutic effect
Objectives: To analyze the frequency and type of the most common benign tumors of the oral mucosa... more Objectives: To analyze the frequency and type of the most common benign tumors of the oral mucosa found at the Hospital Stomatology Service, and to study the clinical characteristics and possible etiological factors. Material and Methods: This is a retrospective study of 300 patients with histologically diagnosed benign tumors of the oral mucosa. Data was compiled for each case, documenting
The use of substances to augment soft tissues as aesthetic purpose is associated with, among othe... more The use of substances to augment soft tissues as aesthetic purpose is associated with, among other undesirable effects, the appearance of foreign body granulomas. The improvements made to these substances have reduced the incidence of adverse reactions, but not eliminated them. We present five cases of foreign body reactions to three different products, dimethylpolysi- loxane (silicone), bovine collagen, and polylactic
Current topics in medicinal chemistry, Jan 4, 2016
Tuberculosis, one of the oldest diseases affecting human beings, is still considered as a world p... more Tuberculosis, one of the oldest diseases affecting human beings, is still considered as a world public health problem by the World Health Organization. Therefore, there is a need for new and more powerful analytical methods for early illness diagnosis. With this idea in mind, the development of a High Fundamental Frequency (HFF) piezoelectric immunosensor for the sensitive detection of tuberculosis was undertaken. A 38 kDa protein secreted by Mycobacterium tuberculosis was first selected as the target biomarker. Then, specific monoclonal antibodies (MAbs) were obtained. Myc-31 MAb, which showed the highest affinity to the analyte, was employed to set up a reference enzyme-linked immunosorbent assay (ELISA) with a limit of detection of 14 ng mL-1 of 38 kDa antigen. For the development of the HFF piezoelectric immunosensor, 100 MHz quartz crystals were used as transducer elements. The gold electrode surface was functionalized by covalent immobilization of the target biomarker through ...
Acoustic wave resonators have become suitable devices for a broad range of sensing applications d... more Acoustic wave resonators have become suitable devices for a broad range of sensing applications due to their sensitivity, low cost, and integration capability, which are all factors that meet the requirements for the resonators to be used as sensing elements for portable point of care (PoC) platforms. In this work, the design, characterization, and validation of a 150 MHz high fundamental frequency quartz crystal microbalance (HFF-QCM) sensor for bio-sensing applications are introduced. Finite element method (FEM) simulations of the proposed design are in good agreement with the electrical characterization of the manufactured resonators. The sensor is also validated for bio-sensing applications. For this purpose, a specific sensor cell was designed and manufactured that addresses the critical requirements associated with this type of sensor and application. Due to the small sensing area and the sensor's fragility, these requirements include a low-volume flow chamber in the nanol...
A deep analysis of the problem associated with oscillators as interface circuits for quartz-cryst... more A deep analysis of the problem associated with oscillators as interface circuits for quartz-crystal-microbalance sensors, reveals that the so-called static capacitance of the sensor is one of the elements that makes the use of oscillators more critical for sensors applications. A phase-locked-loop based circuit specifically designed for compensating the parallel capacitance effects in quartz crystal resonator sensors is presented. This
An extended Butterworth-Van Dyke (EBVD) model to characterize a thickness-shear mode quartz cryst... more An extended Butterworth-Van Dyke (EBVD) model to characterize a thickness-shear mode quartz crystal resonator in a semi-infinite viscoelastic medium is derived by means of analysis of the lumped elements model described by Cernosek et al. [R. W. Cernosek, S. J. Martin, A. R. Hillman, and H. L. Bandey, IEEE Trans. Ultrason. Ferroelectr. Freq. Control 45, 1399 (1998)]. The EBVD model
A new electronic design for continuous motional series resonant frequency monitoring of loaded qu... more A new electronic design for continuous motional series resonant frequency monitoring of loaded quartz crystal resonators is presented. Using this circuit, a low-cost method for a simple determination of equivalent circuit parameters of quartz crystal resonators is described. Measurements made with the proposed system on typical AT cut quartz crystals are in good agreement with those of an Impedance Analyzer.
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000
An extended Butterworth-Van Dyke (EBVD) model with frequency-independent parameters for the chara... more An extended Butterworth-Van Dyke (EBVD) model with frequency-independent parameters for the characterization of a resonant compound formed by a quartz crystal in contact with a finite viscoelastic layer contacting a semi-infinite viscoelastic medium is extracted by analysis of the lumped element model. The formulation of the EBVD model is compared with the complete expression of the electrical admittance of the loaded quartz derived from the transmission line model (TLM). Relative deviations between them do not exceed 3% around 1% bandwidth near resonance. An extended Martin & Granstaff's model and an explicit expression for the frequency shift that supposes an extension of Kanazawa's model for viscoelastic media are obtained. An analysis of the errors associated with the extraction of shear parameters of the coating for different materials prove that, to obtain an error less than 5% in the shear parameters determination, the viscoelastic contribution, defined as the relative error in the thickness computed from the frequency shift by Sauerbrey equation, must be greater than a limit that depends on Q, which is defined as the ratio of the shear storage modulus (G') to shear loss modulus (G"). In the materials studied, polymers in the transition range or in the rubbery state with Q = 1 and 10, the viscoelastic contribution must be higher than 15% and 50%, respectively, for a 5% limit error in the shear parameters extraction. A criterion for a practical determination of the appropriate viscoelastic regimes is indicated.
IEEE International Frequency Control Symposium, 2011
Quartz crystal microbalance (QCM) technique is widely used in in-liquid biochemical applications.... more Quartz crystal microbalance (QCM) technique is widely used in in-liquid biochemical applications. The main challenges remain on the improvement of sensitivity and limit of detection, as well as multianalysis capabilities and reliability. The improvement of sensitivity has been addressed in the last decades by increasing the sensor fundamental frequency; following the increment of the frequency/mass sensitivity with the square of
Medicina oral, patología oral y cirugía bucal, 2009
Sjögren's syndrome is one of the most frequent autoimmune diseases. It is a chronic and syste... more Sjögren's syndrome is one of the most frequent autoimmune diseases. It is a chronic and systemic disorder predominantly found in women, and is characterized by the appearance of a lymphocytic inflammatory infiltrate, with dryness of the oral cavity and eyes, secondary to involvement of the salivary and lacrimal glands. The underlying causal mechanism involves a number of factors and has not been clearly established, though an autoimmune response is known to be triggered, with the accumulation of immune complexes in the gland acini that interfere with gland function. In the oral cavity, xerostomia or hyposialia is the most disabling manifestation for patients, and is accompanied by rapidly progressing caries, candidiasis and an important worsening of buccodental health. The most important complication is a 44-fold increase in the risk of developing non-Hodgkin lymphoma, compared with the general population. The treatment of Sjögren's syndrome is limited to symptomatic managem...
Oral anticoagulants (OACs) antagonizing vitamin K - fundamentally sodium warfarin and acenocoumar... more Oral anticoagulants (OACs) antagonizing vitamin K - fundamentally sodium warfarin and acenocoumarol - are wi- dely used for preventing arterial thromboembolism in patients with atrial fibrillation and/or heart valve prostheses, and for the treatment and prevention of deep venous thrombosis and pulmonary embolism. The handling of these drugs requires correct monitorization and dose adjustment to obtain the desired therapeutic effect
Objectives: To analyze the frequency and type of the most common benign tumors of the oral mucosa... more Objectives: To analyze the frequency and type of the most common benign tumors of the oral mucosa found at the Hospital Stomatology Service, and to study the clinical characteristics and possible etiological factors. Material and Methods: This is a retrospective study of 300 patients with histologically diagnosed benign tumors of the oral mucosa. Data was compiled for each case, documenting
The use of substances to augment soft tissues as aesthetic purpose is associated with, among othe... more The use of substances to augment soft tissues as aesthetic purpose is associated with, among other undesirable effects, the appearance of foreign body granulomas. The improvements made to these substances have reduced the incidence of adverse reactions, but not eliminated them. We present five cases of foreign body reactions to three different products, dimethylpolysi- loxane (silicone), bovine collagen, and polylactic
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