Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331380
Catia Bandeiras, B. Saramago, A. P. Serro
The exact mechanism by which anesthetics induce membrane-mediated modifications that lead to loss of sensation is still an open question. Since lipid rafts are membrane microdomains that have been associated with cell signaling pathways, as well as specific interaction with drugs, they may contribute to that mechanism. The interactions of a canonical liposomal lipid raft model, as well as of a model without cholesterol, with the anesthetics tetracaine (TTC), lidocaine (LDC) and propofol (PPF) were studied using quartz crystal microbalance with dissipation (QCM-D), differential scanning calorimetry (DSC) and phosphorus nuclear magnetic resonance (P-NMR). The three anesthetics induced effects such as membrane flu-idization, depression of phase transition temperatures, liposome swelling and/or viscosity changes of the adsorbed liposome layers on both models. Tetracaine interacts more with raftlike domains, lidocaine induces stronger modifications on POPC/SM liposomes and the results for propofol are not fully conclusive.
{"title":"Interactions between anesthetics and lipid rafts","authors":"Catia Bandeiras, B. Saramago, A. P. Serro","doi":"10.1109/ENBENG.2012.6331380","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331380","url":null,"abstract":"The exact mechanism by which anesthetics induce membrane-mediated modifications that lead to loss of sensation is still an open question. Since lipid rafts are membrane microdomains that have been associated with cell signaling pathways, as well as specific interaction with drugs, they may contribute to that mechanism. The interactions of a canonical liposomal lipid raft model, as well as of a model without cholesterol, with the anesthetics tetracaine (TTC), lidocaine (LDC) and propofol (PPF) were studied using quartz crystal microbalance with dissipation (QCM-D), differential scanning calorimetry (DSC) and phosphorus nuclear magnetic resonance (P-NMR). The three anesthetics induced effects such as membrane flu-idization, depression of phase transition temperatures, liposome swelling and/or viscosity changes of the adsorbed liposome layers on both models. Tetracaine interacts more with raftlike domains, lidocaine induces stronger modifications on POPC/SM liposomes and the results for propofol are not fully conclusive.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"242 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121027033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331357
C. Pereira, N. Martins, L. Gonçalves, M. Ferreira
Diabetic retinopathy has been revealed as the most common cause of blindness among people of working age. For monitoring the pathology image registration algorithms applied to retinal images is very useful. In this work, a novel vessel-based retinal image registration approach is proposed. The segmentation of the vasculature is performed by a multi-agent system model. All these information is then used in a Robust Point Matching Iterative Closest Point algorithm improved by a Region Bootstrap approach. With this preliminary study, the novelty of integrating all these algorithms for image registration preceded by a multi-agents system for image edges detection seems to be efficient for temporal retinal image registration. Consequently, a system developed on basis of this approach could help in screening programs for the diabetic retinopathy prevention.
{"title":"Registration of retinal images by a MAS-ICP approach — A preliminary study","authors":"C. Pereira, N. Martins, L. Gonçalves, M. Ferreira","doi":"10.1109/ENBENG.2012.6331357","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331357","url":null,"abstract":"Diabetic retinopathy has been revealed as the most common cause of blindness among people of working age. For monitoring the pathology image registration algorithms applied to retinal images is very useful. In this work, a novel vessel-based retinal image registration approach is proposed. The segmentation of the vasculature is performed by a multi-agent system model. All these information is then used in a Robust Point Matching Iterative Closest Point algorithm improved by a Region Bootstrap approach. With this preliminary study, the novelty of integrating all these algorithms for image registration preceded by a multi-agents system for image edges detection seems to be efficient for temporal retinal image registration. Consequently, a system developed on basis of this approach could help in screening programs for the diabetic retinopathy prevention.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115030180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331392
J. Tiago, A. P. Serro, M. G. Moutinho
The main purpose of this work is to investigate the release of antibiotics incorporated in dental obturation cements. It constitutes a first approach to the development of a type of drug delivery system with great interest and potential, that still is practically inexistent in the market. Several antibiotics and root canal sealers (RCS) were pretested through microbiological and dissolution tests, respectively in order to select the system(s) to study. Ampicillin was chosen to be incorporated in two commercial RCS, AH Plus® and EndoREZ®. The drug release kinetics was evaluated by high performance chromatography (HPLC) as a function of drug load and film thickness, and its microbiological efficacy after release was proven. For both sealers, ampicillin release occurred in the first few hours and depends on the drug load and film thickness. The relative amount released from EndoREZ® was higher, due to its higher hydrophilicity and porosity.
{"title":"Controlled drug release from dental obturation cements","authors":"J. Tiago, A. P. Serro, M. G. Moutinho","doi":"10.1109/ENBENG.2012.6331392","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331392","url":null,"abstract":"The main purpose of this work is to investigate the release of antibiotics incorporated in dental obturation cements. It constitutes a first approach to the development of a type of drug delivery system with great interest and potential, that still is practically inexistent in the market. Several antibiotics and root canal sealers (RCS) were pretested through microbiological and dissolution tests, respectively in order to select the system(s) to study. Ampicillin was chosen to be incorporated in two commercial RCS, AH Plus® and EndoREZ®. The drug release kinetics was evaluated by high performance chromatography (HPLC) as a function of drug load and film thickness, and its microbiological efficacy after release was proven. For both sealers, ampicillin release occurred in the first few hours and depends on the drug load and film thickness. The relative amount released from EndoREZ® was higher, due to its higher hydrophilicity and porosity.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"314 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122865403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331396
P. Moreira, P. Flores, M. Silva
The main purpose of this work is to present a three dimensional biomechanical multibody foot model suitable to perform forward dynamic analysis. The proposed approach takes into accounts the different contact phenomena that develop between the foot and ground during the stance phase of the human gait. The interaction between the foot and ground bodies is provided by the introduction of a set of spheres under the plantar surface of the foot. A general mathematical methodology for contact detection between the foot and ground surfaces is presented. Then, in a simple way, when the foot-ground contact occurs, appropriate constitutive laws for contact phenomena are applied. These laws take into account the vertical ground reaction force as well as the friction phenomena, namely the Coulomb and viscoelastic friction effects. Finally, the results obtained from computational and experimental analysis are used to discuss the procedures adopted through this work.
{"title":"A biomechanical multibody foot model for forward dynamic analysis","authors":"P. Moreira, P. Flores, M. Silva","doi":"10.1109/ENBENG.2012.6331396","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331396","url":null,"abstract":"The main purpose of this work is to present a three dimensional biomechanical multibody foot model suitable to perform forward dynamic analysis. The proposed approach takes into accounts the different contact phenomena that develop between the foot and ground during the stance phase of the human gait. The interaction between the foot and ground bodies is provided by the introduction of a set of spheres under the plantar surface of the foot. A general mathematical methodology for contact detection between the foot and ground surfaces is presented. Then, in a simple way, when the foot-ground contact occurs, appropriate constitutive laws for contact phenomena are applied. These laws take into account the vertical ground reaction force as well as the friction phenomena, namely the Coulomb and viscoelastic friction effects. Finally, the results obtained from computational and experimental analysis are used to discuss the procedures adopted through this work.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"2016 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114612963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331351
P. Nolasco, P. Carvalho, A. J. Anjos, J. Marques, F. Cabrita, Eduardo Fabiano da Costa, A. Matos
The microstructure, local chemistry, crystallography and mechanical properties of submandibular sialoliths have been characterized by powder X-ray diffraction, electron microscopy combined with X-ray spectroscopy and ultramicro-indentation assays. The sialoliths presented highly mineralized, lamellar and globular regions. The fairly homogeneous mineralized regions are constituted by hydroxyapatite, whitlockite and brushite. Lamellar regions consisted of alternating layers of mineralized material and organic matter, with a concentric morphology pointing to a chronologic cyclic formation. Globular regions are composed of organic matter globules presenting high sulphur content. The Young modulus and hardness increased with the mineralization degree of the sialoliths. Nevertheless the relatively high amounts of compliant and soft organic matter present in the sialoliths may play a major role in the relatively low success of shock wave therapeutics for sialolith fragmentation.
{"title":"Structural characterization of salivary calculi","authors":"P. Nolasco, P. Carvalho, A. J. Anjos, J. Marques, F. Cabrita, Eduardo Fabiano da Costa, A. Matos","doi":"10.1109/ENBENG.2012.6331351","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331351","url":null,"abstract":"The microstructure, local chemistry, crystallography and mechanical properties of submandibular sialoliths have been characterized by powder X-ray diffraction, electron microscopy combined with X-ray spectroscopy and ultramicro-indentation assays. The sialoliths presented highly mineralized, lamellar and globular regions. The fairly homogeneous mineralized regions are constituted by hydroxyapatite, whitlockite and brushite. Lamellar regions consisted of alternating layers of mineralized material and organic matter, with a concentric morphology pointing to a chronologic cyclic formation. Globular regions are composed of organic matter globules presenting high sulphur content. The Young modulus and hardness increased with the mineralization degree of the sialoliths. Nevertheless the relatively high amounts of compliant and soft organic matter present in the sialoliths may play a major role in the relatively low success of shock wave therapeutics for sialolith fragmentation.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115824978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331389
A. Batista
3,4-methylenedioxymethamphetamine (MDMA) is a ring-substituted amphetamine derivative. It is associated with euphoric states, however, it may also cause death. Its actions are caused by alterations on extracellular monoamine neurotransmitters. In the present study, we resorted to electroretinography to assess the acute and long term effects on the retina of MDMA administration. Its effects on glial reactivity were also matter of study. The results showed that a single MDMA administration did not significantly affect the electroretinogram (ERG) response. Repeated MDMA administration caused significant differences in the scotopic tests but similar results were observed for the saline-treated animals. We purpose that stress may influence ERG recordings. Regarding the effects of MDMA on glial reactivity, no significant changes were observed; however, a tendency for an increase in GFAP expression for both single and multiple MDMA administration was detected.
{"title":"Exploring the impact of ecstasy on retinal physiology: A pioneer study","authors":"A. Batista","doi":"10.1109/ENBENG.2012.6331389","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331389","url":null,"abstract":"3,4-methylenedioxymethamphetamine (MDMA) is a ring-substituted amphetamine derivative. It is associated with euphoric states, however, it may also cause death. Its actions are caused by alterations on extracellular monoamine neurotransmitters. In the present study, we resorted to electroretinography to assess the acute and long term effects on the retina of MDMA administration. Its effects on glial reactivity were also matter of study. The results showed that a single MDMA administration did not significantly affect the electroretinogram (ERG) response. Repeated MDMA administration caused significant differences in the scotopic tests but similar results were observed for the saline-treated animals. We purpose that stress may influence ERG recordings. Regarding the effects of MDMA on glial reactivity, no significant changes were observed; however, a tendency for an increase in GFAP expression for both single and multiple MDMA administration was detected.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134638554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331364
J. Loureiro, M. Coelho, S. Rocha, Maria do Carmo Pereira
The conformational changes and aggregation of amyloid β peptide (Aβ) are associated to Alzheimer's disease (AD). The aim of this work is to study the structure and fibril assembly of Aβ in the presence of charged and nonionic amphiphiles, and β-sheet breaker peptides/conjugates. It is expected that these molecules will inhibit Aβ aggregation. Liposome systems will be developed as carriers for these peptide conjugates to cross the brain blood barrier (BBB).
{"title":"Design of potential therapeutic peptides and carriers to inhibit amyloid β peptide aggregation","authors":"J. Loureiro, M. Coelho, S. Rocha, Maria do Carmo Pereira","doi":"10.1109/ENBENG.2012.6331364","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331364","url":null,"abstract":"The conformational changes and aggregation of amyloid β peptide (Aβ) are associated to Alzheimer's disease (AD). The aim of this work is to study the structure and fibril assembly of Aβ in the presence of charged and nonionic amphiphiles, and β-sheet breaker peptides/conjugates. It is expected that these molecules will inhibit Aβ aggregation. Liposome systems will be developed as carriers for these peptide conjugates to cross the brain blood barrier (BBB).","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117296913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331394
A. Castro, P. Flores, A. Completo, J. Simões
The purpose for this work was to analyze the structural effects of the implantation of contemporary patellofemoral prosthesis on femur cancellous bone. In fact, studies on the state of strain/stress on patellofemoral arthroplasty are still very limited. The influence of the geometry and rigidity of the bone-implant interface is discussed, applying the Finite Element Method. One of the major reasons for the failure of currently available knee implants is the stress shielding effect. In loading situations, the bone is less requested, so the rate of bone remodeling decreases. The results showed that elastic strain is lower on bone areas close to the studied models of patellofemoral prosthesis, on the period after the implantation. Later on, bone rupture by fatigue may also occur, due to high strain, particularly on the models with fixation pins for the prosthesis. Furthermore, contact analyses showed that stability is best promoted without fixation pins.
{"title":"Development of a new femoral component for patellofemoral prosthesis","authors":"A. Castro, P. Flores, A. Completo, J. Simões","doi":"10.1109/ENBENG.2012.6331394","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331394","url":null,"abstract":"The purpose for this work was to analyze the structural effects of the implantation of contemporary patellofemoral prosthesis on femur cancellous bone. In fact, studies on the state of strain/stress on patellofemoral arthroplasty are still very limited. The influence of the geometry and rigidity of the bone-implant interface is discussed, applying the Finite Element Method. One of the major reasons for the failure of currently available knee implants is the stress shielding effect. In loading situations, the bone is less requested, so the rate of bone remodeling decreases. The results showed that elastic strain is lower on bone areas close to the studied models of patellofemoral prosthesis, on the period after the implantation. Later on, bone rupture by fatigue may also occur, due to high strain, particularly on the models with fixation pins for the prosthesis. Furthermore, contact analyses showed that stability is best promoted without fixation pins.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129051853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331374
M. Dias Silva, C. V. Ferreria, H. Oliveira, P. Fonte, L. Jesus, R. Salvador, J. Silvestre, P. Crespo
We present a system comprising multiple coils immersed in a conducting liquid allowing for unprecedented deep, whole-brain transcranial magnetic stimulation (TMS). The system exploits a configuration of large-coils with dedicated spatial asymmetries in order to spare current induction in the retinas and in the human trunk, optimizing deep-brain stimulation down to the center of the brain. The resulting axially-induced currents of this system are prone to magnetic steering by means of dipole and quadrupole-focusing electromagnet (DC) assemblies, with its viability also analyzed in this work. Finite-element methods were applied onto a spherical head model complemented by an ellipsoidal torso. The head model comprises skin, skull, cerebral spinal fluid, and brain tissue. Results, not yet comprising the magnetic-steering capability of the system, show deep-brain induced currents reaching 53% at 10-cm penetration (brain center) in respect to surface (cortex) maximum. For comparison, state-of-the-art published data reach 47% relative induction at 8-cm depth only. This system counterparts well-known limiting effects occurring due to the enhancement of current densities at the brain/surface interface by immersing the stimulating coils (and partially the head of the patient) into a conducting liquid such as an electrolyte solution or a liquid metal. These results may potentially enhance clinical applicability of TMS in a number of pathologies such as Alzheimer's disease, parkinsonism, depression, sleep disorders, pain management, stroke rehabilitation, tinnitus, trigeminal neuralgia, brain palsy,and resolution of epileptic seizures, among others.
{"title":"Multiple coils in a conducting liquid for deep and whole-brain transcranial magnetic stimulation. II. Multiple-frequency excitation","authors":"M. Dias Silva, C. V. Ferreria, H. Oliveira, P. Fonte, L. Jesus, R. Salvador, J. Silvestre, P. Crespo","doi":"10.1109/ENBENG.2012.6331374","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331374","url":null,"abstract":"We present a system comprising multiple coils immersed in a conducting liquid allowing for unprecedented deep, whole-brain transcranial magnetic stimulation (TMS). The system exploits a configuration of large-coils with dedicated spatial asymmetries in order to spare current induction in the retinas and in the human trunk, optimizing deep-brain stimulation down to the center of the brain. The resulting axially-induced currents of this system are prone to magnetic steering by means of dipole and quadrupole-focusing electromagnet (DC) assemblies, with its viability also analyzed in this work. Finite-element methods were applied onto a spherical head model complemented by an ellipsoidal torso. The head model comprises skin, skull, cerebral spinal fluid, and brain tissue. Results, not yet comprising the magnetic-steering capability of the system, show deep-brain induced currents reaching 53% at 10-cm penetration (brain center) in respect to surface (cortex) maximum. For comparison, state-of-the-art published data reach 47% relative induction at 8-cm depth only. This system counterparts well-known limiting effects occurring due to the enhancement of current densities at the brain/surface interface by immersing the stimulating coils (and partially the head of the patient) into a conducting liquid such as an electrolyte solution or a liquid metal. These results may potentially enhance clinical applicability of TMS in a number of pathologies such as Alzheimer's disease, parkinsonism, depression, sleep disorders, pain management, stroke rehabilitation, tinnitus, trigeminal neuralgia, brain palsy,and resolution of epileptic seizures, among others.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131946811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-18DOI: 10.1109/ENBENG.2012.6331356
M. B. de Matos, A. P. Piedade, C. Alvarez‐Lorenzo, A. Concheiro, M. Braga, H. C. de Sousa
Biodegradable polymeric foams of proper pore sizes, geometries and densities, are already known to be useful biomaterials for several pharmaceutical, biomedical and tissue engineering applications. Moreover, the combination of these biodegradable polymeric foams with biocompatible inorganic nanoparticles and with bioactive substances may lead to the generation of novel composite biomaterials presenting improved chemical, physical and biological properties. This work reports preliminary results on the use of supercritical carbon dioxide (scCO2) processes, namely of scCO2-assisted foaming and of scCO2-assisted impregnation/deposition, for the development of dexamethasone-loaded composite biomaterials prepared with poly(E-caprolactone) (PCL) and with mesoporous MCM-41 silica nanoparticles (SNPs). Pure PCL and PCL/MCM-41 composite materials (90:10 and 70:30, wt.%) were processed by scCO2 foaming at different experimental density (801.4 and 901.2 Kg/m3), processing time (2 and 14 hours) and depressurization rate (0.22 and 3.0 L/min) conditions. In addition, mesoporous MCM-41 SNPs were loaded with dexamethasone (DXMT) by a scCO2 impregnation/deposition method at the above referred experimental conditions, and by DXMT sorption from aqueous and from ethanolic DXMT liquid solutions (at 37 oC and atmospheric pressure). All prepared materials were characterized by simultaneous differential thermal analysis (SDT) and texturometry. DXMT release studies were performed in order to evaluate and to compare the obtained DXMT release profiles from loaded MCM-41 SNPs. Obtained results demonstrated the feasibility of using scCO2 impregnation/deposition and scCO2 foaming methods for the development of DXMT-loaded PCL/MCM-41 composite materials to be applied in hard tissue biomedical applications.
{"title":"SCF-assisted processing of dexamethasone-loaded poly(ε-caprolactone)/MCM-41 materials for biomedical applications","authors":"M. B. de Matos, A. P. Piedade, C. Alvarez‐Lorenzo, A. Concheiro, M. Braga, H. C. de Sousa","doi":"10.1109/ENBENG.2012.6331356","DOIUrl":"https://doi.org/10.1109/ENBENG.2012.6331356","url":null,"abstract":"Biodegradable polymeric foams of proper pore sizes, geometries and densities, are already known to be useful biomaterials for several pharmaceutical, biomedical and tissue engineering applications. Moreover, the combination of these biodegradable polymeric foams with biocompatible inorganic nanoparticles and with bioactive substances may lead to the generation of novel composite biomaterials presenting improved chemical, physical and biological properties. This work reports preliminary results on the use of supercritical carbon dioxide (scCO2) processes, namely of scCO2-assisted foaming and of scCO2-assisted impregnation/deposition, for the development of dexamethasone-loaded composite biomaterials prepared with poly(E-caprolactone) (PCL) and with mesoporous MCM-41 silica nanoparticles (SNPs). Pure PCL and PCL/MCM-41 composite materials (90:10 and 70:30, wt.%) were processed by scCO2 foaming at different experimental density (801.4 and 901.2 Kg/m3), processing time (2 and 14 hours) and depressurization rate (0.22 and 3.0 L/min) conditions. In addition, mesoporous MCM-41 SNPs were loaded with dexamethasone (DXMT) by a scCO2 impregnation/deposition method at the above referred experimental conditions, and by DXMT sorption from aqueous and from ethanolic DXMT liquid solutions (at 37 oC and atmospheric pressure). All prepared materials were characterized by simultaneous differential thermal analysis (SDT) and texturometry. DXMT release studies were performed in order to evaluate and to compare the obtained DXMT release profiles from loaded MCM-41 SNPs. Obtained results demonstrated the feasibility of using scCO2 impregnation/deposition and scCO2 foaming methods for the development of DXMT-loaded PCL/MCM-41 composite materials to be applied in hard tissue biomedical applications.","PeriodicalId":399131,"journal":{"name":"2012 IEEE 2nd Portuguese Meeting in Bioengineering (ENBENG)","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121589944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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