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Eudragit^®-PEG Nanoparticles: Physicochemical Characterization and Interfacial Tension Measurements

Open Journal of Biophysics 2024年第2期14卷 121-131页

作者： Papa Mady Sy Sidy Mouhamed Dieng Alphonse Rodrigue Djiboune Louis Augustin Diaga Diouf Boucar Ndong gora mbaye Mounibé Diarra Laboratory of Physics and Pharmaceutical Biophysics Faculty of Medicine Pharmacy and Odontology UCAD Dakar Senegal Laboratory of Galenic Pharmacy Faculty of Medicine Pharmacy and Odontology UCAD Dakar Senegal Laboratory of Medical Biophysics and Nuclear Medicine Faculty of Medicine Pharmacy and Odontology UCAD Dakar Senegal

The objectives of this study are to understand the mechanisms involved in the stabilization of water/oil interfaces by polymeric nanoparticles (NPs) (Eudragit®). Eudragit L100 NPs of various sizes and Zeta potentials were studied and compared at a water/cyclohexane model interface using a droplet tensiometer (Tracker Teclis, Longessaigne, France). The progressive interfacial adsorption of the NPs in the aqueous phase was monitored by tensiometry. The model interface was maintained and observed in a drop tensiometer, analyzed via axisymmetric drop shape analysis (ADSA), to determine the interfacial properties. Given the direct relationship between the stability of Pickering emulsions (emulsions stabilized by solid nanoparticles) and the interfacial properties of these layers, different nanoparticle systems were compared. Specifically, Eudragit NPs of different sizes were examined. Moreover, the reduction of the Zeta potential with PEG-6000 induces partial aggregation of the NPs (referred to as NP flocs), significantly impacting the stability of the interfacial layer. Dynamic surface tension measurements indicate a significant decrease in interfacial tension with Eudragit® nanoparticles (NPs). This reduction correlates with the size of the NPs, highlighting that this parameter does not operate in isolation. Other factors, such as the contact angle and wettability of the nanoparticles, also play a critical role. Notably, larger NPs further diminished the interfacial tension. This study enhances our understanding of the stability of Pickering emulsions stabilized by Eudragit® L100 polymeric nanoparticles.

关键词： Nanoparticles Eudragit® PEG Interfacial Tension Pickering Emulsion

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Contribution of Bone Scintigraphy in the Diagnosis of a Case of SAPHO in the Nuclear Medicine Department of Idrissa Pouye General Hospital (Dakar, Senegal)

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Open Journal of Medical Imaging 2024年第1期14卷 1-9页

作者： El Hadji Amadou Lamine Bathily Kalidou Gueye Serigne Moussa Badiane Mamoudou Salif Djigo gora Thiaw Ousseynou Diop Olatounde Herbert Fachinan Papa Mady Sy Alfonse Rodrigue Djiboune Kokou Fofo Toussaint Adambounou Louis Augustin Diaga Diouf Boucar Ndong gora mbaye Omar Ndoye Mounibé Diarra Mamadou Mbodj Nuclear Medicine Department Idrissa Pouye General Hospital (HOGIP) Dakar Senegal Biophysical Laboratory FMPO Cheikh Anta Diop University (UCAD) Dakar Senegal Biophysical Laboratory UFR2S Gaston Berger University (UGB) Saint-Louis Senegal Nuclear Medicine Department Hospital Dalal Jamm Dakar Senegal Laboratory of Physical and Pharmaceutical Biophysics FMPO Cheikh Anta Diop University Dakar Senegal Biophysical Laboratory University of Lome Lome Togo

Introduction: The acronym SAPHO (Synovitis, Acne, Pustulosis, Hyperostosis and Osteitis) is a syndrome combining osteoarticular and cutaneous manifestations. It occurs mainly between the ages of 30 and 50. Sternocostoclavicular hyperostosis is one of the main distinguishing features. We report a case of SAPHO in Dakar diagnosed by bone scintigraphy. Observation: 28-year-old Senegalese women presented with left shoulder pain and relative functional impotence for over 2 years. Examination revealed right sternoclavicular hyperostosis and left shoulder pain on palpation. Questioning revealed a history of acne and hyperostosis of the right first toe. Bone scintigraphy, performed after injection of 630 MBq of 99mTc-HMDP, revealed: hyperfixation of the bilateral (right++) manubrio-sternal and sternoclavicular junction, producing the classic bull’s horn image;hyperfixation of the left shoulder with an inflammatory appearance;hyperfixation of the sacroiliac joints suggestive of bilateral sacroiliitis;hyperfixation of the right first toe;two mandibular hyper fixations probably related to dental damage. This scintigraphic appearance in one was strongly suggestive of SAPHO syndrome. Conclusion: SAPHO syndrome, related to spondyloarthropathy, associates cutaneous and osteoarticular signs. It is characterized by frequent delays in diagnosis due to poor recognition. Soy is an invaluable diagnostic tool, enabling us to assess the extent of the disease and its evolution.

关键词： SAPHO Bone Scintigraphy Young Woman Senegalese

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Iodine 131 Treatment in Graves’ Disease in a West African Country: Preliminary Study about 25 Cases in Senegal

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Open Journal of Biophysics 2024年第1期14卷 56-72页

作者： El Hadji Amadou Lamine Bathily Serigne Moussa Badiane Mamoudou Salif Djigo gora Thiaw Kalidou Gueye Ousseynou Diop Boucar Ndong Kokou Fofo Toussaint Adambounou Alphonse Rodrigue Djiboune Papa Mady Sy Mamadou Soumbounou Mohamed Chekhma Louis Augustin Diaga Diouf gora mbaye Omar Ndoye Mounibé Diarra Mamadou Mbodj Nuclear Medicine Department General Hospital of Idrissa Pouye (HOGIP) Dakar Senegal Biophysical Laboratory Cheikh Anta Diop University (UCAD) Dakar Senegal Biophysical Laboratory Gaston Berger University (UGB) Saint-Louis Nuclear Medicine Department Hospital Dalal Jamm Dakar Senegal Biophysical Laboratory University of Lome Lome Togo Laboratory of Physical and Pharmaceutical Biophysics Cheikh Anta Diop University Dakar Senegal

Introduction: Graves’ disease is the most common cause of hyperthyroidism. Its treatment uses synthetic antithyroid drugs but the use of aggressive radical therapy such as surgery or non-aggressive therapy such as iodine-131 is not uncommon. Treatment of Graves’ disease with radioactive iodine or iratherapy is a simple, inexpensive, well-tolerated treatment. It was introduced in Senegal in 2016. We report through this work the preliminary assessment of the only nuclear medicine service in Senegal in the management of Graves’ disease by iodine-131. Patients and Methods: Retrospective study of the first cases of Graves’ disease treated with iratherapy in Senegal. Socio-demographic, clinical, paraclinical, therapeutic and evolutionary aspects were studied. Radiation protection rules have been implemented and contraception has been effective for six months in women of childbearing age. Results: 25 patients were collected with a mean age of 45 years, twenty women (80%), a family goiter in 24% and a psycho-affective context in 64% of cases. Thyrotoxicosis syndrome was associated with goiter in 68% of patients and exophthalmos in 64%. Thyroid ultrasound performed in 20 patients showed vascular goiter in 80% and thyroid scintigraphy in 3 patients, homogeneous and diffuse hyperfixation. TRAK dosed in 8 patients was still positive. All patients had received first-line medical treatment. The average duration of this treatment was more than 18 months in 92%. The empirically used iodine-131 activity averaged 15.35 mCi. Oral corticosteroid therapy was prescribed in 7 patients for the prevention of malignant orbitopathy. No early side effects were noted. The remission rate at 3 months was 52% and at 6 months was 88% to 92%. Conclusion: The effectiveness of radioactive iodine, in particular ablative doses in the treatment of hyperthyroidism, is no longer to be demonstrated. Taking into account our socioeconomic context, iratherapy should be a treatment of choice for hyperthyroidism with a good quality/price ratio and excellent t

关键词： Graves’ Disease Iratherapy Iodine-131 Senegal

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Kohonen’s Algorithm Applied to the Scintigraphic Image for an Aid in the Diagnosis of Prostate Cancer Metastasis

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Open Journal of Medical Imaging 2022年第2期12卷 37-47页

作者： Boucar Ndong El Hadji Amadou Lamine Bathily Mamoudou Salif Djigo Mamadou Lamine Mboup François Kaly Kanta Ka Ousseynou Diop Ibrahima Thiam gora mbaye Omar Ndoye Mamadou Mbodj Biophysics and Nuclear Medicine Laboratory Cheikh Anta Diop University Dakar Senegal Sustainable Development and Society Doctoral School Thies University Thies Senegal Laboratoire du traitement de l’information/ESP/UCAD Senegal Radiotherapy Department of the National Hospital University Center Dalal Jamm Guédiawaye Dakar Sénégal Physics Pharmaceutical Laboratory Cheikh Anta Diop University Dakar Senegal

To partition the scintigraphic image, several methods are used, among which is Kohonen’s self-organizing map algorithm. The objective of this study was to perform an ascending hierarchical classification (HAC) on the results of the Kohonen self-organizing map. This makes it possible to carry out the second phase necessary for the elaboration of the classifier by grouping the neurons as well as possible into 3 classes then by reconstituting the scintigraphic image from the 3 classes. This partition proceeds by successive groups, thus merging at each iteration two subsets of neurons using a measure of similarity which is Ward’s method. In this method, the algorithm aggregates the nearest neurons into classes. This allows us to obtain a dendrogram that looks like a tree. And this one needs to be cut. And to have an adequate cut-off level, we have established the variation of the Davies Bouldin index as a function of the number of classes. The minimum value of this index gave the optimal number of classes which corresponded to 3 in the study. These three groups A, B, C have a variable intensity. This intensity can be high, it can be medium or low. The high, medium and low intensities corresponded respectively to metastases for class A, to degenerative or inflammatory phenomena for class B and to normal radiopharmaceutical uptake for class C. To confirm this strong suspicion, we performed reconstructions using a filter. And after this reconstruction, we had images like at the entrance. And for the interpretation of these images, we used a visual metric. This enabled us to note that for the interval [0 - 50[, the image is not contrasted and no lesion could be detected. Over the interval [50 - 200[, we observed the distribution of the radiopharmaceutical over the entire skeletal whole body. On this reconstruction interval, the visual metric shows hypofixation in the bladder and areas suspected of metastases. Over the interval [200 - 250[, we detected hyperfixations linked to degenerative, inflammatory or metastatic lesi

关键词： Neural Networks Hierarchical Ascending Classification Scintigraph

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Multiple Emulsions Able to Be Used for Oral Administration of Active Pharmaceutical Ingredients: Physico-Chemical Parameters Study of Different Phases

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Journal of Modern Physics 2020年第10期11卷 1528-1535页

作者： Louis Augustin Diaga Diouf Alphonse Rodrigue Djiboune Mamadou Soumboundou Sidy Mouhamed Dieng Papa Mady Sy gora mbaye Mounibé Diarra Pharmaceutical Physics and Biophysics Laboratory Faculty of Medicine Pharmacy and Odontology Cheikh Anta Diop University of Dakar Dakar Senegal Pharmaceutical Physics and Biophysics Laboratory Healthy UFR of Thies University of Thies Thies Senegal Galenic and Industrial Pharmacy Laboratory Healthy UFR of Thies University of Thies Thies Senegal

Multiple emulsions are of great therapeutic interest especially in the administration of medicines which can be inactivated by digestive enzymes;moreover the researches of formulation not being often easy, a control of the different phases physicochemical parameters would be of great interest in rapid formulations and at low cost. When formulating emulsions, the preliminary tests, also known as formulation tests, constitute a step which can be long and expensive because of the quantity of reagents that can be used. A rigorous methodology could thus be of great interest, which is at the aim of our study which consists of evaluating the physico-chemical parameters of different phases used to make thus multiple emulsions. In our study, physico-chemical parameters such as conductivity, pH, density, viscosity, and surface tension have been studied by direct measurement using equipment and also by means of suitable mounting. The results showed that the pH and the surface tension have an important role in the prediction of the stability of emulsions, these latter must be of the same order of magnitude. For all phases conductivity does not have too much interest apart from helping to determine the type of the emulsion.

关键词： Active Pharmaceutical Ingredients Multiple Emulsions Stability Physico-Chemical Parameters

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Water/Oil Pickering Emulsion Stabilized by Magnesium Oxide Particles: A Potential System with Two Active Substances (Paracetamol and Griseofulvin)

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Open Journal of Biophysics 2018年第2期8卷 68-84页

作者： Papa Mady Sy Alphonse Rodrigue Djiboune Louis Augustin Diaga Diouf Mamadou Soumboundou Boucar Ndong Augustin Ndiaye Sidy M. Dieng Ousseynou Diop El Hadji A. L. Bathily gora mbaye Mack Faye Mamadou Mbodj Mounibé Diarra Laboratory of Physics and Pharmaceutical Biophysics Faculty of Medicine Pharmacy and Odontology UCAD Dakar Senegal Laboratory of Medical Biophysics and Nuclear Medicine Faculty of Medicine Pharmacy and Odontology UCAD Dakar Senegal

Pickering emulsions are systems without surfactants, stabilized by solid particles. These emulsions are experiencing a renewed interest, on the one hand, because it is preferable to limit the use of synthetic surfactants for toxicological and environmental reasons and, on the other hand, the need to make new formulations in order to control the drug release patterns by encapsulation or controlled release. Thus, we were interested in the formulation and evaluation of W/O Pickering emulsions stabilized by particles of magnesium oxide with paracetamol in the internal phase and griseofulvin in the external phase. The Bancroft rule served as a model for the formulation. The emulsification was carried out by progressively adding an aqueous phase dispersed in an oil-dispersing phase using a turbo rotor stator mixer. The stability of these emulsions was studied using several parameters (droplet size, pH, viscosity, conductivity ...) and the qualitative and quantitative analysis of the active ingredients by UV-visible spectrophotometry. The results obtained showed that the dye test and the conductivity measurement confirmed the W/O nature of these emulsions. Some parameters such as droplet size, pH and viscosity were strongly influenced by the amounts of magnesium oxide particles and the two active ingredients used. The qualitative and quantitative analysis of the active ingredients confirmed the presence of griseofulvin in the oil phase and paracetamol in the aqueous phase. Thus, we have succeeded in developing a stable W/O Pickering emulsion with magnesium oxide particles. In addition, we were able to incorporate paracetamol into the dispersed phase and griseofulvin into the dispersing phase of the emulsion.

关键词： Emulsion Pickering-Mgo-Griseofulvin-Paracetamol

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Inventory of Radiation Protection in Hospitals of Level III in Senegal

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Open Journal of Biophysics 2021年第4期11卷 397-406页

作者： Boucar Ndong Sidi Ahmed Dia Mamadou Salif Djigo Herbert Fachinan El Hadji Lamine Bathily Ousseynou Diop Kanta Ka Gérard Léra Kelvin Akpo El Hadji Fallou Diouf Louis Auguinstin Diaga Diouf Pape Mady Sy Alphonse Djiboune gora mbaye Maguette Diagne Omar Ndoye Mamadou Mbodji Laboratoire de Biophysique Médecine Nucléaire Universite Cheikh Anta Diop Dakar Senegal Service de Médecine du Travail Universite Cheikh Anta Diop Dakar Senegal Faculté de Médecine Université de Parakou Parakou Benin Service de Radiothérapie de Dalal Jamm Dakar Senegal Service de Radiologie de l’Hô pital Aristide Le Dantec Dakar Senegal Laboratoire de Physique Pharmaceutique Universite Cheikh Anta Diop Dakar Senegal Service de Radiothérapie de l’Hô pital Aristide Le Dantec Dakar Senegal

The aim of this study was to evaluate the level of protection of employees who are exposed to radiation in a level III hospital establishment. It was a descriptive cross-sectional survey of six months’ duration, involving eight level III Hospitals (Aristide Le Dantec, Fann, Hoggy, Hear, Abass Ndao, Pikine, Touba, and Thiès) in Senegal. Sixty-one of the one hundred questionnaires were recovered (overall response rate of 61%). The population of the study was mainly female (54.1%). The average age was 38.57 with extremes ranging from 23 to 65 years old. In the places where ionizing radiation sources are handled, only at the Aristide Le Dantec Hospital did we find a “competent person in radiation protection”. This explained the lack of a classification of employees and work areas. Forty out of sixty-one (73.77%) had no knowledge of the basic principles of radiation protection (justification, optimisation, dose limitation) and had not ever taken radiation holidays. For radiovigilance, exposure time limits to ionizing radiation concerned only 29/61 or 47.54% of the study population. The inverse square law of distance was known by only 40 workers, of whom 15 had no compliance. We found the presence of dosifilms in only 7/61 or 11.47% of the workers. On the other hand, the use of lead aprons was well established and concerned 57/61 workers, i.e., 93.44%. In sum, ionizing radiation causes adverse health effects. The absence of a good radiation protection culture in Senegal requires the presence of at least 4 to 5 competent persons in radiation protection for quality training of workers in radiobiology, radiopathology and radiation protection.

关键词： Ionizing Radiation Radiation Protection Workers Senegal

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Back Illuminated N/P/P+Bifacial Silicon Solar Cell under Modulated Short-Wavelength: Determination of Base Optimum Thickness

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Energy and Power Engineering 2021年第5期13卷 207-220页

作者： Mamadou Sall Dianguina Diarisso Mame Faty mbaye Fall gora Diop Mor Ndiaye Khady Loum Gregoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology Cheikh Anta Diop University Dakar Senegal University Institute of Technology University of Thiès Thiès Sénégal Ecole Polytechnique de Thiès Thiès Sénégal

A bifacial silicon solar cell under monochromatic illumination in frequency modulation by the rear side is being studied for the optimization of base thickness. The density of photogenerated carriers in the base is obtained by resolution of the continuity equation, with the help of boundary conditions at the junction surface (n+/p) and the rear face (p/p+) of the base. For a short wavelength corresponding to a high absorption coefficient, the AC photocurrent density is calculated and represented according to the excess minority carrier’s recombination velocity at the junction, for different modulation frequency values. The expression of the AC recombination velocity of excess minority carriers at the rear surface of the base of the solar cell is then deduced, depending on both, the absorption coefficient of the silicon material and the thickness of the base. Compared to the intrinsic AC recombination velocity, the optimal thickness is extracted and modeled in a mathematical relationship, as a decreasing function of the modulated frequency of back illumination. Thus under these operating conditions, a maximum short-circuit photocurrent is obtained and a low-cost bifacial solar cell can be achieved by reducing material (Si) to elaborate the base thickness.

关键词： Bifacial Silicon Solar Cell AC Recombination Velocity-Base Thickness Short-Wavelength

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AC Back Surface Recombination Velocity in n+-p-p+Silicon Solar Cell under Monochromatic Light and Temperature

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Journal of Electromagnetic Analysis and Applications 2021年第5期13卷 67-81页

作者： Mame Faty mbaye Fall Idrissa Gaye Dianguina Diarisso gora Diop Khady Loum Nafy Diop Khalidou Mamadou Sy Mor Ndiaye Gregoire Sissoko Ecole Polytechnique de Thiès Thiès Sénégal Institute of Technology University of Thiès Thiès Sénégal Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal

Excess minority carrier’s diffusion equation in the base of monofaciale silicon solar cell under frequency modulation of monochromatic illumination is resolved. Using conditions at the base limits involving recombination velocities Sf and Sb, respectively at the junction (n+/p) and back surface (p+/p), the AC expression of the excess minority carriers’ density δ (T, ω) is determined. The AC density of photocurrent Jph (T, ω) is represented versus recombination velocity at the junction for different values of the temperature. The expression of the AC back surface recombination velocity Sb of minority carriers is deduced depending on the frequency of modulation, temperature, the electronic parameters (D (ω)) and the thickness of the base. Bode and Nyquist diagrams are used to analyze it.

关键词： Silicon Solar Cell AC Back Surface Recombination Velocity Temperature Bode and Nyquist Diagrams

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Diffusion Coefficient at Resonance Frequency as Applied to n+/p/p+ Silicon Solar Cell Optimum Base Thickness Determination

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Journal of Electromagnetic Analysis and Applications 2020年第10期12卷 145-158页

作者： Amadou Mar Ndiaye Sega Gueye Mame Faty mbaye Fall gora Diop Amadou Mamour Ba Mamadou Lamine Ba Ibrahima Diatta Lemrabott Habiboullah Gregoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal Ecole Polytechnique de Thiès Thiès Sénégal Département Génie Electrique Ecole Supérieure Polytechnique de Nouakchott Nouakchott Mauritanie

The modelling and determination of the geometric parameters of a solar cell are important data, which influence the evaluation of its performance under specific operating conditions, as well as its industrial development for a low cost. In this work, an n+/p/p+ crystalline silicon solar cell is studied under monochromatic illumination in modulation and placed in a constant magnetic field. The minority carriers’ diffusion coefficient (D(ω, B), in the (p) base leads to maximum values (Dmax) at resonance frequencies (ωr). These values are used in expressions of AC minority carriers recombination velocity (Sb(Dmax, H)) in the rear of the base, to extract the optimum thickness while solar cell is subjected to these specific conditions. Optimum thickness modelling relationships, depending respectively on Dmax, ωr and B, are then established, and will be data for industrial development of low-cost solar cells for specific use.

关键词： Silicon Solar Cell Resonance Frequency Magnetic Field Recombination Velocity Base Thickness

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