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Papers by Fábio Florenzano

Journal of Molecular Liquids, 1997

Vesicles of dioctadecyltrimethylammonium chloride were prepared by sonication, membrane extrusion... more Vesicles of dioctadecyltrimethylammonium chloride were prepared by sonication, membrane extrusion and dichloromethane injection. The diameter of the vesicles were determined using quasi-elastic light scattering and freeze fracture electron microscopy. The incorporation of ...

Polymer Bulletin, 2011

Relationships able to predict the behavior of polymers based on their chemical structure are nece... more Relationships able to predict the behavior of polymers based on their chemical structure are necessary for the rational synthesis of materials with desired properties. The state-of-art of polymer chemistry allows one to synthesize, using techniques such as RAFT, polymers with tailored chemical structures to study that kind of relationships. In this study, RAFT was used to synthesize copolymers—poly(methyl methacrylate)-block-poly[(2-dimethylamino)ethyl methacrylate]—that

Plastic and Reconstructive Surgery, 2008

... cases. J Oral Pathol Med. 2004;33:115–120. 3. Dijkema SJ, van der Lei B, Kibbelaar RE. New-Fi... more ... cases. J Oral Pathol Med. 2004;33:115–120. 3. Dijkema SJ, van der Lei B, Kibbelaar RE. New-Fill injections may induce late-onset foreign body granulomatous reaction. Plast Reconstr Surg. 2005;115:76e–78e. Reconstruction ...

Journal of Molecular Liquids, 1997

Vesicles of dioctadecyltrimethylammonium chloride were prepared by sonication, membrane extrusion... more Vesicles of dioctadecyltrimethylammonium chloride were prepared by sonication, membrane extrusion and dichloromethane injection. The diameter of the vesicles were determined using quasi-elastic light scattering and freeze fracture electron microscopy. The incorporation of water soluble probes in the vesicles allowed the determination of a molar volume of 6 to 8 L/mole for the CH2Cl2 injected vesicles and 1.0 L/mole for the membrane extruded vesicles, in very good agreement with the data calculated from the vesicle diameters. The permeability of the injected CH2Cl2 vesicles is dependent on temperature and probe structure. Membrane extruded vesicles are more permeable than injected vesicles, both below and above the phase transition temperature.

International Journal of Polymer Analysis and Characterization, 1997

Real time monitoring of ultraviolet degradation of polystyrene with varying degrees of methylviny... more Real time monitoring of ultraviolet degradation of polystyrene with varying degrees of methylvinyl ketone (MVK) substitutions was carried out. This automated technique is demonstrated to be rapid, accurate and quantitative, yielding the absolute degradation rate constant in terms of number of bonds broken per second per initial g/mol of polymer mass. The MVK substituted heteropolymers yielded degradation rates around two

European Polymer Journal, 2005

Drug Delivery, 2001

The stability of liposome preparations under the action of the nonionic detergent Triton X-100 wa... more The stability of liposome preparations under the action of the nonionic detergent Triton X-100 was measured using the fluorescent molecular probe octadecylrhodamine B (R18). The probe inserted in the lipid bilayer shows a self-quenched fluorescence and the degree of quenching depends both on the probe concentration and the phase state of the lipid membrane. The addition of detergent to the liposomes produces a steep decrease in self-quenching caused by dilution of the probe in the bilayer. The curves of steady-state fluorescence intensity show an abrupt change in slope that corresponds to the point at which liposomes break down into lipid-detergent mixed entities that are different from the earlier liposome-monodisperse population. The lytic process was followed in parallel by dynamic light scattering (DLS), and the analysis of the DLS results agree with the interpretation of the fluorescence measurements. The probe R18 therefore is a useful marker to test the stability of liposome preparations. The advantages of the present method are discussed by comparison with other techniques.

Colloid and Polymer Science, 2012

Brazilian Journal of Medical and Biological Research, 1997

The effect of urea on biomimetic aggregates (aqueous and reversed micelles, vesicles and monolaye... more The effect of urea on biomimetic aggregates (aqueous and reversed micelles, vesicles and monolayers) was investigated to obtain insights into the effect of the denaturant on structured macromolecules. Direct evidence obtained from light scattering (static and dynamic), monolayer maximum isothermal compression and ionic conductivity measurements, together with indirect evidence from fluorescence photodissociation, fluorescence suppression, and thermal reactions, strongly indicates the direct interaction mechanism of urea with the aggregates. Preferential solvation of the surfactant headgroups by urea results in an increase in the monomer dissociation degree (when applied), which leads to an increase in the area per headgroup and also in the loss of counterion affinities.

Analytical and Bioanalytical Chemistry, 2013

A new restricted access molecularly imprinted polymer coated with bovine serum albumin (RAMIP-BSA... more A new restricted access molecularly imprinted polymer coated with bovine serum albumin (RAMIP-BSA) was developed, characterized, and used for direct analysis of chlorpromazine in human plasma samples. The RAMIP-BSA was synthesized using chlorpromazine, methacrylic acid, and ethylene glycol dimethacrylate as template, functional monomer, and cross-linker, respectively. Glycerol dimethacrylate and hydroxy methyl methacrylate were used to promote a hydrophilic surface (high density of hydroxyl groups). Afterward, the polymer was coated with BSA using glutaraldehyde as cross-linker, resulting in a protein chemical shield around it. The material was able to eliminate ca. 99% of protein when a 44-mg mL(-1) BSA aqueous solution was passed through it. The RAMIP-BSA was packed in a column and used for direct analysis of chlorpromazine in human plasma samples in an online column switching high-performance liquid chromatography system. The analytical calibration curve was prepared in a pool of human plasma samples with chlorpromazine concentrations ranging from 30 to 350 μg L(-1). The correlation coefficient obtained was 0.995 and the limit of quantification was 30 μg L(-1). Intra-day and inter-day precision and accuracy presented variation coefficients and relative errors lower than 15% and within -15 and 15%, respectively. The sample throughput was 3 h(-1) (sample preparation and chromatographic analysis steps) and the same RAMIP-BSA column was efficiently used for about 90 cycles.

Journal of Molecular Liquids, 1997

Vesicles of dioctadecyltrimethylammonium chloride were prepared by sonication, membrane extrusion... more Vesicles of dioctadecyltrimethylammonium chloride were prepared by sonication, membrane extrusion and dichloromethane injection. The diameter of the vesicles were determined using quasi-elastic light scattering and freeze fracture electron microscopy. The incorporation of ...

Polymer Bulletin, 2011

Relationships able to predict the behavior of polymers based on their chemical structure are nece... more Relationships able to predict the behavior of polymers based on their chemical structure are necessary for the rational synthesis of materials with desired properties. The state-of-art of polymer chemistry allows one to synthesize, using techniques such as RAFT, polymers with tailored chemical structures to study that kind of relationships. In this study, RAFT was used to synthesize copolymers—poly(methyl methacrylate)-block-poly[(2-dimethylamino)ethyl methacrylate]—that

Plastic and Reconstructive Surgery, 2008

... cases. J Oral Pathol Med. 2004;33:115–120. 3. Dijkema SJ, van der Lei B, Kibbelaar RE. New-Fi... more ... cases. J Oral Pathol Med. 2004;33:115–120. 3. Dijkema SJ, van der Lei B, Kibbelaar RE. New-Fill injections may induce late-onset foreign body granulomatous reaction. Plast Reconstr Surg. 2005;115:76e–78e. Reconstruction ...

Journal of Molecular Liquids, 1997

Vesicles of dioctadecyltrimethylammonium chloride were prepared by sonication, membrane extrusion... more Vesicles of dioctadecyltrimethylammonium chloride were prepared by sonication, membrane extrusion and dichloromethane injection. The diameter of the vesicles were determined using quasi-elastic light scattering and freeze fracture electron microscopy. The incorporation of water soluble probes in the vesicles allowed the determination of a molar volume of 6 to 8 L/mole for the CH2Cl2 injected vesicles and 1.0 L/mole for the membrane extruded vesicles, in very good agreement with the data calculated from the vesicle diameters. The permeability of the injected CH2Cl2 vesicles is dependent on temperature and probe structure. Membrane extruded vesicles are more permeable than injected vesicles, both below and above the phase transition temperature.

International Journal of Polymer Analysis and Characterization, 1997

Real time monitoring of ultraviolet degradation of polystyrene with varying degrees of methylviny... more Real time monitoring of ultraviolet degradation of polystyrene with varying degrees of methylvinyl ketone (MVK) substitutions was carried out. This automated technique is demonstrated to be rapid, accurate and quantitative, yielding the absolute degradation rate constant in terms of number of bonds broken per second per initial g/mol of polymer mass. The MVK substituted heteropolymers yielded degradation rates around two

European Polymer Journal, 2005

Drug Delivery, 2001

The stability of liposome preparations under the action of the nonionic detergent Triton X-100 wa... more The stability of liposome preparations under the action of the nonionic detergent Triton X-100 was measured using the fluorescent molecular probe octadecylrhodamine B (R18). The probe inserted in the lipid bilayer shows a self-quenched fluorescence and the degree of quenching depends both on the probe concentration and the phase state of the lipid membrane. The addition of detergent to the liposomes produces a steep decrease in self-quenching caused by dilution of the probe in the bilayer. The curves of steady-state fluorescence intensity show an abrupt change in slope that corresponds to the point at which liposomes break down into lipid-detergent mixed entities that are different from the earlier liposome-monodisperse population. The lytic process was followed in parallel by dynamic light scattering (DLS), and the analysis of the DLS results agree with the interpretation of the fluorescence measurements. The probe R18 therefore is a useful marker to test the stability of liposome preparations. The advantages of the present method are discussed by comparison with other techniques.

Colloid and Polymer Science, 2012

Brazilian Journal of Medical and Biological Research, 1997

The effect of urea on biomimetic aggregates (aqueous and reversed micelles, vesicles and monolaye... more The effect of urea on biomimetic aggregates (aqueous and reversed micelles, vesicles and monolayers) was investigated to obtain insights into the effect of the denaturant on structured macromolecules. Direct evidence obtained from light scattering (static and dynamic), monolayer maximum isothermal compression and ionic conductivity measurements, together with indirect evidence from fluorescence photodissociation, fluorescence suppression, and thermal reactions, strongly indicates the direct interaction mechanism of urea with the aggregates. Preferential solvation of the surfactant headgroups by urea results in an increase in the monomer dissociation degree (when applied), which leads to an increase in the area per headgroup and also in the loss of counterion affinities.

Analytical and Bioanalytical Chemistry, 2013

A new restricted access molecularly imprinted polymer coated with bovine serum albumin (RAMIP-BSA... more A new restricted access molecularly imprinted polymer coated with bovine serum albumin (RAMIP-BSA) was developed, characterized, and used for direct analysis of chlorpromazine in human plasma samples. The RAMIP-BSA was synthesized using chlorpromazine, methacrylic acid, and ethylene glycol dimethacrylate as template, functional monomer, and cross-linker, respectively. Glycerol dimethacrylate and hydroxy methyl methacrylate were used to promote a hydrophilic surface (high density of hydroxyl groups). Afterward, the polymer was coated with BSA using glutaraldehyde as cross-linker, resulting in a protein chemical shield around it. The material was able to eliminate ca. 99% of protein when a 44-mg mL(-1) BSA aqueous solution was passed through it. The RAMIP-BSA was packed in a column and used for direct analysis of chlorpromazine in human plasma samples in an online column switching high-performance liquid chromatography system. The analytical calibration curve was prepared in a pool of human plasma samples with chlorpromazine concentrations ranging from 30 to 350 μg L(-1). The correlation coefficient obtained was 0.995 and the limit of quantification was 30 μg L(-1). Intra-day and inter-day precision and accuracy presented variation coefficients and relative errors lower than 15% and within -15 and 15%, respectively. The sample throughput was 3 h(-1) (sample preparation and chromatographic analysis steps) and the same RAMIP-BSA column was efficiently used for about 90 cycles.