Ricardo Geraldo de Sousa

A dual-functional [SBA-15/Fe 3 O 4 /P( N -iPAAm)] hybrid system as a potential nanoplatform for biomedical application

The synthesis strategy of a multifunctional system of [SBA-15/Fe3O4/P(N-iPAAm)] hybrids of interest for bioapplications was explored. Magnetite nanoparticles coated by mesoporous silica were prepared by an alternative chemical route using neutral surfactant and without the application of any functionalization method. Monomer adsorption followed by in situ polymerization initiated by a radical was the adopted procedure to incorporate the hydrogel into the pore channels of silica nanocomposite. Characterization of the materials was carried out by using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), N2 adsorption, transmission electron microscopy (TEM), and Temperature programmed reduction studies (TPR). Their application as drug delivery system using atenolol as a model drug to assess the influence of the application of low frequency alternating magnetic fields on drug release was evaluated. The structural characteristics of the magnetic hybrid nanocomposite, including the effect of the swelling behavior on heating by the application of an alternating magnetic field, are presented and discussed.

Síntese e caracterização térmica e química do copolímero poli(D,L-lactídeo-co-glicolídeo)

O copolimero poli(D,L-lactideo-co-glicolideo) apresenta-se como um dos polimeros de maior interesse para aplicacao na area medica. O fato de ser biorreabsorvivel, biocompativel, atoxico e ter uma cinetica de degradacao que pode ser modificada pela razao entre os monomeros na copolimerizacao justifica tal interesse. Neste trabalho, os copolimeros foram sintetizados a 175 oC, por meio da abertura dos aneis dos dimeros ciclicos dos monomeros D,L-lactideo e glicolideo, na presenca do iniciador octanoato de estanho e do co-iniciador alcool laurilico. O controle eficiente do vacuo no meio reacional, aliado a adequada agitacao, foram fundamentais para o sucesso da sintese. Para caracterizacao dos copolimeros sintetizados foram empregadas as tecnicas de calorimetria exploratoria diferencial (DSC), termogravimetria (TG) e espectroscopia na regiao do infravermelho (FTIR). Foram analisados nao somente os produtos de reacao, mas tambem os monomeros de partida. A nova rota de sintese utilizada mostrou-se adequada, sendo os copolimeros poli(D,L-lactideo-co-glicolideo) obtidos com sucesso.

Combining mesoporous silica–magnetite and thermally-sensitive polymers for applications in hyperthermia

Abstract In this work, the synthesis strategy of a multifunctional system of [SBA-16/P(N-iPAAm)/Fe3O4] hybrids of interest for magneto-hyperthermia was explored. Magnetite nanoparticles coated by mesoporous silica were prepared by an alternative chemical route using neutral surfactant and without the application of any functionalization method. Monomer adsorption followed by in situ polymerization initiated by a radical was used to incorporate the hydrogel into the pore channels of the silica nanocomposite. Structural and magnetic characterization of the obtained materials was carried out by using thermal analysis, X-ray diffraction, N2 adsorption desorption isotherms, 57Fe Mössbauer spectroscopy, vibrating sample magnetometry and transmission electron microscopy. Measurements of alternating current magnetic-field-induced heating behaviour under different applied magnetic fields showed that the [SBA-16/P(N-iPAAm)/Fe3O4] hybrid here synthesized is suitable as a hyperthermia agent for biological applications.

Molecularly imprinted polymer for determination of lumefantrine in human plasma through chemometric-assisted solid-phase extraction and liquid chromatography

Lumefantrine is the first-choice treatment of Falciparum uncomplicated malaria. Recent findings of resistance to lumefantrine has brought attention for the importance of therapeutic monitoring, since exposure to subtherapeutic doses of antimalarials after administration is a major cause of selection of resistant parasites. Therefore, this study focused on the development of innovative, selective, less expensive and stable molecularly imprinted polymers (MIPs) for solid-phase extraction (SPE) of lumefantrine from human plasma to be used in drug monitoring. Polymers were synthesized by precipitation polymerization and chemometric tools (Box-Behnken design and surface response methodology) were employed for rational optimization of synthetic parameters. Optimum conditions were achieved with 2-vinylpyridine as monomer, ethylene glycol dimethacrylate as crosslinker and toluene as porogen, at molar ratio of 1:6:30 of template/monomer/crosslinker and azo-bisisobutyronitrile as initiator at 65 °C. The MIP obtained was characterized and exhibited high thermal stability, adequate surface morphology and porosity characteristics and high binding properties, with high affinity (adsorption capacity of 977.83 μg g-1) and selectivity (imprinting factor of 2.44; and selectivity factor of 1.48 and selectivity constant of 1.44 compared with halofantrine). Doehlert matrix and fractional designs were satisfactorily used for development and optimization of a MISPE-HPLC-UV method for determination of lumefantrine. The method fulfilled all validation parameters, with recoveries ranging from 83.68% to 85.42%, and was applied for quantitation of the drug in plasma from two healthy volunteers, with results of 1407.89 and 1271.35 ng mL-1, respectively. Therefore, the MISPE-HPLC-UV method optimized through chemometrics provided a rapid, highly selective, less expensive and reproducible approach for lumefantrine drug monitoring.

Treatment of Prosthetic Joint Infection with Debridement, Antibiotics and Irrigation with Implant Retention - a Narrative Review

Prosthetic joint infection usually requires combined medical and surgical therapy. While revision surgery is widely considered to be the gold standard surgical procedure, debridement, antibiotics and irrigation with implant retention is a very appealing alternative. There is however great controversy regarding its real worth with success rates ranging from 0% to over 90%. A number of different patient and host related variables as well as specific aspects of surgical and medical management have been described as relevant for the final outcome. Along this paper, the authors will provide the readers with a critical narrative review of the currently available literature while trying to provide concise and practical treatment recommendations regarding adequate patient selection criteria, proper surgical technique and optimal antibiotic therapy.

Economic Impact of Prosthetic Joint Infection - an Evaluation Within the Portuguese National Health System

Introduction: Prosthetic infection is a devastating complication of arthroplasty and carries significant economic burden. The objective of this study was to analyze the economic impact of prosthetic hip and knee infection in Portuguese National Health System. Material and Methods: Case-control study carried out from January 2014 to December 2015. The mean costs of primary arthroplasties and prosthetic revision surgeries for non-infectious reasons were compared with the costs of prosthetic infections treated with debridement and preservation of the prosthesis or with two-stage exchange arthroplasty.The reimbursement for these cases was also evaluated and compared with its real costs. Results:A total of 715 primary arthroplasties, 35 aseptic revisions, 16 surgical debridements and 15 revisions for infectious reasons were evaluated. The cost of primary arthroplasties was 3,230€ in the hips and 3,618€ in the knees. The cost of aseptic revision was 6,089€ in the hips and 7,985€ in the knees. In the cases treated with debridement and implant retention the cost was 5,528€ in the hips and 4,009€ in the knees. In cases of infections treated with a two-stage revision the cost was 11,415€ and 13,793€ for hips and knees, respectively. Conclusion: As far as we know this is the first study that analyzes the economic impact of prosthetic infection in the Portuguese context. Although direct compensation for treating infected cases is much lower than calculated costs, infected cases push the overall hospital case-mix-index upwards thus increasing financial compensation for the entire cohort of treated patients. This knowledge will allow for more informed decisions about health policies in the future.

Síntese e caracterização de MIP com fenilalanina visando sua aplicação na técnica de SPE

Polimeros Molecularmente Impressos (MIPs) sao polimeros sinteticos que apresentam alta seletividade a uma molecula de interesse. O objetivo deste trabalho foi a sintese e caracterizacao de MIPs para aplicacao na extracao em fase solida (SPE), visando a determinacao de fenilalanina. Os MIPs foram sintetizados a partir do MAA, fenilalanina, EGDMA, AIBN, em cloroformio. Tambem foi sintetizado o polimero nao-impresso (NIP), para controle da seletividade dos MIPs. A dessorcao da fenilalanina foi realizada em extrator Soxhlet. Os MIPs e NIP foram caracterizados pelas tecnicas de analise: FTIR, UV-Vis, MEV, DSC e TG. O MIP apresentou maior capacidade adsortiva a fenilalanina do que o NIP, com uma taxa media de adsorcao de 55% comparada a 11% para o NIP. Por MEV o MIP apresentou superficie mais porosa, importante caracteristica para aplicacao em SPE. Os estudos realizados mostraram que o MIP sintetizado apresentou grande potencial para aplicacao em tecnica de SPE.

Multifunctional Nanocomposites Based on Mesoporous Silica: Potential Applications in Biomedicine

In the last decade, significant research efforts were devoted to obtaining materials with welldefined nanostructures for a wide range of applications (Hamley, 2003; Soler-Illia et al., 2002; Paul & Sharma, 2006). Mesoporous silica materials like M41S, HMS, SBAn, FSM, and MSU, among others, are a fairly new type of material that has pores in the mesoscopic range of 2–50 nm (Wan et al., 2007). The characteristic features of ordered mesoporous materials are their monodispersed and adjustable pore size in an inert and biocompatible matrix with an easily modified surface. Procedures to obtain ordered mesoporous silicates rely on the micelle-forming properties of a surfactant, whose chemical composition, size, and concentration control the structural dimensions of the final material (Zhao et al., 1998). In most cases, ionic and neutral surfactants have been employed as templates to direct mesophase formation based on the electrostatic and hydrogen-bonding interaction. Polymerization of the inorganic precursor and further removal of the surfactants result in a rigid silica shell that delimits the structural shape of the mesopores. In such processing routes, the resultant material presents an ordered hexagonal arrangement of unidirectional mesoporous channels and a high surface area, above 800 m2/g, depending on the synthesis conditions. Figure 1 shows the scheme of structure formation mediated by inorganic mesoporous structure-directing agent. The intrinsic uniform porous structure of this class of compounds with their large specific surface area and pore volume, associated with surface silanol groups, give these materials a significant potential for applications as matrices of many chemical species, such as organic molecules, metals, and polymeric materials. The combination of different materials to obtain nanocomposites is of great research interest due to their potential medical applications, such as tissue engineering, drug delivery devices, and hyperthermia, among others (Vallet-Regi et al., 2008; Souza et al., 2010). In this work, the recent developments in nanocomposites based on mesoporous materials (also referred to as hybrid materials) will be overviewed. Two categories of nanocomposites