Comparative study of the quality of breast meat of free-range chicken (Gallus gallus domesticus) and conventional chicken (Gallus gallus).

This study compares the physicochemical characteristics of breast meat (Pectoralis major) from conventional chicken and free-range chicken production systems. Analyses of pH, instrumental color measurement, weight loss from cooking (WLC), and water retention capacity (WRC) were carried out. Average pH values were slightly higher for conventional chicken samples. WLC did not show a significant difference between conventional and free-range chicken samples. The WRC was better and higher for the free-range chicken samples than the conventional ones. The mean values for luminosity (L*) were within the normal range, with slightly higher values for conventional chicken. In chromatids a* and b*, there was a tendency towards a more reddish color for free-range chicken samples. The differences found for types of production can be explained mainly by the difference in age at slaughter, the degree of physical activity, animal feeding, among other characteristics that differentiate an animal raised by the extensive system from the intensive system.

Strawberries treated with biodegradable film containing plant extracts.

Strawberry (Fragaria x ananassa Duch.) is a highly perishable fruit whose characteristics make it susceptible to developing microorganisms. Plant extracts have been studied as an alternative to pesticides to control spoilage microorganisms, responding to the expectation of the population seeking a healthier way of life. The fungus Botrytis cinerea is a facultative pathogen of vegetables, which can affect all stages of the development of several fruits, such as the strawberry, where it causes gray rot. Trichilia catigua (catuaba), Paullinia cupana (guarana), Stryphnodendron barbatiman (barbatimão), and Caesalpinia peltophoroides (sibipiruna) are planted in the Brazilian flora and have demonstrated pharmacological properties in their extracts. This work aimed to treat strawberries with a biodegradable film containing extracts of these species to evaluate strawberry conservation. There were notable distinctions in mass loss between the extract-treated and control samples. The pH, total acidity (TA), and soluble solids parameters exhibited consistently significant means across both sets of samples. Luminosity increased over the course of days in the color parameters, with the exception of strawberries coated with guarana. The red color showed greater intensity, except for those coated with barbatimão extract. Considering the results, it is possible to conclude that the coatings used can become an alternative to enhance the conservation of strawberries.

Comparative analysis of the use of natural and synthetic antioxidants in chicken meat: an update review.

The search for healthy foods has attracted the industry's attention to developing products that use natural ingredients, including natural antioxidants. Antioxidants act as free radicals or oxygen scavengers, inhibiting lipid oxidation and adversely affecting meat products' sensory and nutritional quality. Several synthetic antioxidants have been used in the meat industry; however, studies point to health risks related to their consumption. Such fact drives research into natural antioxidants extracted from grains, oilseeds, spices, fruits, and vegetables, which may have a health-promoting effect. This manuscript evaluates the effectiveness of several natural antioxidants in improving the quality and shelf life of chicken meat products during processing, storage, and distribution. The potential effects of natural antioxidants widely used in chicken products are also discussed. It can be concluded that these natural antioxidants are possible substitutes for synthetic ones. However, their use can affect the product's characteristics.

Evaluation of physicochemical properties of Nile tilapia skin collagen extracted in acid médium.

Tilapia has high-temperature tolerance, can breed in captivity, grow fast, and have excellent cost-benefit. Because of these characteristics, this species is of great interest in aquaculture and, currently, the most produced fish in Brazil. However, by increasing tilapia production, there was also a rise in the amount of organic waste, mainly from filleting, which discards 70% of waste. There are many studies on collagen extraction from tilapia skin as an alternative to reduce these residues and add commercial value. In this work, the extraction of protein concentrate was tested using an acid protocol, in which the tilapia skins underwent a pre-treatment in an acid medium and saline precipitation, with variations in time and concentration. After its extraction, the skin was evaluated for ash, moisture, protein, solubility, and pH. The protein concentrate obtained showed low ash contents, and the humidity is within those presented by the literature. The protein concentrate showed levels from 68.73 to 80.58% of protein and a low solubility between 4.03 to 6.93%. In conclusion, acid extraction is a possible means of collagen extraction, and tilapia skin is a good alternative to reuse waste generated in the fish industry.

Ivermectin as a possible treatment for COVID-19: a review of the 2022 protocols.

Ivermectin is a safe and effective drug in humans and has been approved for use in numerous parasitic infections for over 50 years. In addition, many studies have already shown its antiviral activity. Ivermectin is generally well tolerated, with no indication of central nervous system-associated toxicity at doses up to 10 times the highest FDA-approved dose of 200 µg/kg. The in vitro results of ivermectin for reducing SARS-CoV-2 viral load are promising and show that Ivermectin kills SARS-CoV-2 within 48 hours. A hypothesized mechanism of action for this drug is a likely inhibition of IMPα/ß1-mediated nuclear import of viral proteins as demonstrated for other RNA viruses. However, controlled and randomized studies are needed to prove its effectiveness in COVID-19 in humans. In a single in vivo study with published results, patients confirmed to be infected with SARS-CoV-2 received at least one dose of ivermectin at any time during hospitalization. The use of ivermectin was associated with lower mortality during treatment with COVID-19, especially in patients who required increased inspired oxygen or ventilatory support. Additionally, 81 studies with the clinical use of ivermectin in humans are being carried out worldwide according to ClinicalTrials.gov. However, none of these data has been published so far. However, private and public entities in Brazil have been adopting this drug in their protocols as prophylaxis and in the initial phase of the disease. In addition, ivermectin has been used in mass treatment to prevent onchocerciasis and lymphatic filariasis in sub-Saharan Africa for many years. Surprisingly, this region has the lowest proportional mortality rate among the continents, despite the increasing numbers of infected people released by the World Health Organization.

Quality of cosmetics with active caffeine in cream and gel galenic bases prepared by compounding pharmacies / Qualidade de cosméticos com cafeína ativa em bases galênicas em creme e gel preparadas por farmácias de manipulação

As there is a great scarcity of studies on the importance of good compounding practices in the preparation of cosmetics, this study aimed to evaluate the quality control of cosmetics with active ingredient caffeine for the treatment of cellulite prepared by magistrals pharmacies. Microbiological analyzes, pH determination, color measurement, quantification of the percentage of the active ingredient caffeine and viscosity in creams and gels with 5% of the active ingredient caffeine were performed. In the microbiological analysis, the presence of molds and yeasts was verified above the permitted level according to the Brazilian pharmacopoeia. The pH decreased over time, contributing to the formulations becoming more acidic. In the color parameters, it was found that pharmacy F4 showed a brownish color, both for the gel and for the cream. The percentage of caffeine was within specifications in all formulations and the viscosity remained unchanged during the shelf life of the samples. It is important that the compounding pharmacies demand more effectively the commitment of the team, as well as the analysis of the raw material according to the microbiological control regulations to translate into the quality of the products prepared by the pharmacies and favor the consumer in the effective objective that the product you want to achieve.

Como há uma grande escassez de estudos sobre a importância de boas práticas de manipulação na elaboração de cosméticos, o presente estudo teve como objetivo avaliar o controle de qualidade de cosméticos com princípio ativo cafeína para o tratamento de celulite, elaborados por farmácias de manipulação de Campo Mourão. Foram realizadas análises microbiológicas, determinação do pH, mensuração da coloração, quantificação da porcentagem do princípio ativo cafeína e viscosidade em cremes e geís com 5% do princípio ativo cafeína. Nas análises microbiológicas foi verificada a presença de bolores e leveduras acima do pemitido segundo a farmacopéia brasileira. O pH diminuiu ao longo do tempo, contribuindo para que as formulações ficassem mais ácidas. Nos parâmetros de cor averiguou-se que a farmácia F4 apresentou uma coloração amarronzada, tanto para o gel quanto para o creme. A porcentagem de cafeína estava dentro das especificações em todas as formulações e a viscosidade se manteve inalterada durante o prazo de validade das amostras. Com o propósito de um melhor preparo magistral é importante que as farmácias de manipulação exijam de forma mais eficaz o comprometimento da equipe, bem como a análise da matéria-prima segundo as regulamentações de controle microbiológico. Além disso, a implementação de normas mais rígidas e o melhor controle da matéria-prima e das formulações finais fazem com que a qualidade dos produtos manipulados pelas farmácias magistrais seja aumentada significativamente, favorecendo o consumidor na efetiva finalidade a que o produto objetiva atingir.

Challenges of nanotechnology in cosmetic permeation with caffeine / Desafios da nanotecnologia na permeação cosmética com cafeína

The evolution of beauty market and personal care is constant in Brazil as well in the rest of the world. Technological advances have brought up nanotechnology to the cosmetological field, employing active principles at atoms enveloped by vesicles, in order to take the active principle precisely to the target tissue to optimize the results achieved because of the considerable ease to cross skin barriers. Manufacturing of nanotechnology cosmetics is confronted with low absorption capacity. One of the many active principle found in cosmetic industry is caffeine, a pseudoalkaloid from the xanthine group used as a stimulant with the mechanism of the lipolytic action. This active is widely used in a esthetics and cosmetics field in treatments involving dysfunctions such as localized fat and fibroedema geloid. To work out perfectly, the principle active need to interact and create a set of factors that includes lipolysis intensification. The caffeine encapsulation in gel-based nanocosmetics has the purpose of taking this active up to the adipocyte, the target cell, for mentioned dysfunctions treatment. Thus, we aim to present a review of how has been, the use of caffeine in the production of cosmetics.

A evolução do mercado de beleza e cuidados pessoais é constante no Brasil e no resto do mundo. Os avanços tecnológicos trouxeram a nanotecnologia para o campo cosmetológico, empregando princípios ativos em átomos envolvidos por vesículas, a fim de levar o princípio ativo precisamente ao tecido alvo para otimizar os resultados alcançados devido à considerável facilidade de atravessar barreiras cutâneas. A fabricação de cosméticos nanotecnológicos é confrontada com baixa capacidade de absorção. Um dos muitos princípios ativos encontrados na indústria cosmética é a cafeína, um pseudoalocalóide do grupo xantina usado como estimulante no mecanismo da ação lipolítica. Este ativo é amplamente utilizado no campo da estética e dos cosméticos em tratamentos que envolvem disfunções, como gordura localizada e fibroedema gelóide. Para funcionar perfeitamente, o princípio ativo precisa interagir e criar um conjunto de fatores que inclui a intensificação da lipólise. O encapsulamento de cafeína em nanocosméticos à base de gel tem o objetivo de levar esse ativo até o adipócito, a célula alvo, para o tratamento de disfunções mencionado. Assim, objetivamos apresentar uma revisão de como tem sido o uso de cafeína na produção de cosméticos.

Challenges of nanotechnology in cosmetic permeation with caffeine / Desafios da nanotecnologia na permeação cosmética com cafeína

The evolution of beauty market and personal care is constant in Brazil as well in the rest of the world. Technological advances have brought up nanotechnology to the cosmetological field, employing active principles at atoms enveloped by vesicles, in order to take the active principle precisely to the target tissue to optimize the results achieved because of the considerable ease to cross skin barriers. Manufacturing of nanotechnology cosmetics is confronted with low absorption capacity. One of the many active principle found in cosmetic industry is caffeine, a pseudoalkaloid from the xanthine group used as a stimulant with the mechanism of the lipolytic action. This active is widely used in a esthetics and cosmetics field in treatments involving dysfunctions such as localized fat and fibroedema geloid. To work out perfectly, the principle active need to interact and create a set of factors that includes lipolysis intensification. The caffeine encapsulation in gel-based nanocosmetics has the purpose of taking this active up to the adipocyte, the target cell, for mentioned dysfunctions treatment. Thus, we aim to present a review of how has been, the use of caffeine in the production of cosmetics.

A evolução do mercado de beleza e cuidados pessoais é constante no Brasil e no resto do mundo. Os avanços tecnológicos trouxeram a nanotecnologia para o campo cosmetológico, empregando princípios ativos em átomos envolvidos por vesículas, a fim de levar o princípio ativo precisamente ao tecido alvo para otimizar os resultados alcançados devido à considerável facilidade de atravessar barreiras cutâneas. A fabricação de cosméticos nanotecnológicos é confrontada com baixa capacidade de absorção. Um dos muitos princípios ativos encontrados na indústria cosmética é a cafeína, um pseudoalocalóide do grupo xantina usado como estimulante no mecanismo da ação lipolítica. Este ativo é amplamente utilizado no campo da estética e dos cosméticos em tratamentos que envolvem disfunções, como gordura localizada e fibroedema gelóide. Para funcionar perfeitamente, o princípio ativo precisa interagir e criar um conjunto de fatores que inclui a intensificação da lipólise. O encapsulamento de cafeína em nanocosméticos à base de gel tem o objetivo de levar esse ativo até o adipócito, a célula alvo, para o tratamento de disfunções mencionado. Assim, objetivamos apresentar uma revisão de como tem sido o uso de cafeína na produção de cosméticos.

Quality of cosmetics with active caffeine in cream and gel galenic bases prepared by compounding pharmacies / Qualidade de cosméticos com cafeína ativa em bases galênicas em creme e gel preparadas por farmácias de manipulação

As there is a great scarcity of studies on the importance of good compounding practices in the preparation of cosmetics, this study aimed to evaluate the quality control of cosmetics with active ingredient caffeine for the treatment of cellulite prepared by magistrals pharmacies. Microbiological analyzes, pH determination, color measurement, quantification of the percentage of the active ingredient caffeine and viscosity in creams and gels with 5% of the active ingredient caffeine were performed. In the microbiological analysis, the presence of molds and yeasts was verified above the permitted level according to the Brazilian pharmacopoeia. The pH decreased over time, contributing to the formulations becoming more acidic. In the color parameters, it was found that pharmacy F4 showed a brownish color, both for the gel and for the cream. The percentage of caffeine was within specifications in all formulations and the viscosity remained unchanged during the shelf life of the samples. It is important that the compounding pharmacies demand more effectively the commitment of the team, as well as the analysis of the raw material according to the microbiological control regulations to translate into the quality of the products prepared by the pharmacies and favor the consumer in the effective objective that the product you want to achieve.

Como há uma grande escassez de estudos sobre a importância de boas práticas de manipulação na elaboração de cosméticos, o presente estudo teve como objetivo avaliar o controle de qualidade de cosméticos com princípio ativo cafeína para o tratamento de celulite, elaborados por farmácias de manipulação de Campo Mourão. Foram realizadas análises microbiológicas, determinação do pH, mensuração da coloração, quantificação da porcentagem do princípio ativo cafeína e viscosidade em cremes e geís com 5% do princípio ativo cafeína. Nas análises microbiológicas foi verificada a presença de bolores e leveduras acima do pemitido segundo a farmacopéia brasileira. O pH diminuiu ao longo do tempo, contribuindo para que as formulações ficassem mais ácidas. Nos parâmetros de cor averiguou-se que a farmácia F4 apresentou uma coloração amarronzada, tanto para o gel quanto para o creme. A porcentagem de cafeína estava dentro das especificações em todas as formulações e a viscosidade se manteve inalterada durante o prazo de validade das amostras. Com o propósito de um melhor preparo magistral é importante que as farmácias de manipulação exijam de forma mais eficaz o comprometimento da equipe, bem como a análise da matéria-prima segundo as regulamentações de controle microbiológico. Além disso, a implementação de normas mais rígidas e o melhor controle da matéria-prima e das formulações finais fazem com que a qualidade dos produtos manipulados pelas farmácias magistrais seja aumentada significativamente, favorecendo o consumidor na efetiva finalidade a que o produto objetiva atingir.

Challenges of nanotechnology in cosmetic permeation with caffeine

Abstract The evolution of beauty market and personal care is constant in Brazil as well in the rest of the world. Technological advances have brought up nanotechnology to the cosmetological field, employing active principles at atoms enveloped by vesicles, in order to take the active principle precisely to the target tissue to optimize the results achieved because of the considerable ease to cross skin barriers. Manufacturing of nanotechnology cosmetics is confronted with low absorption capacity. One of the many active principle found in cosmetic industry is caffeine, a pseudoalkaloid from the xanthine group used as a stimulant with the mechanism of the lipolytic action. This active is widely used in a esthetics and cosmetics field in treatments involving dysfunctions such as localized fat and fibroedema geloid. To work out perfectly, the principle active need to interact and create a set of factors that includes lipolysis intensification. The caffeine encapsulation in gel-based nanocosmetics has the purpose of taking this active up to the adipocyte, the target cell, for mentioned dysfunctions treatment. Thus, we aim to present a review of how has been, the use of caffeine in the production of cosmetics.

Resumo A evolução do mercado de beleza e cuidados pessoais é constante no Brasil e no resto do mundo. Os avanços tecnológicos trouxeram a nanotecnologia para o campo cosmetológico, empregando princípios ativos em átomos envolvidos por vesículas, a fim de levar o princípio ativo precisamente ao tecido alvo para otimizar os resultados alcançados devido à considerável facilidade de atravessar barreiras cutâneas. A fabricação de cosméticos nanotecnológicos é confrontada com baixa capacidade de absorção. Um dos muitos princípios ativos encontrados na indústria cosmética é a cafeína, um pseudoalocalóide do grupo xantina usado como estimulante no mecanismo da ação lipolítica. Este ativo é amplamente utilizado no campo da estética e dos cosméticos em tratamentos que envolvem disfunções, como gordura localizada e fibroedema gelóide. Para funcionar perfeitamente, o princípio ativo precisa interagir e criar um conjunto de fatores que inclui a intensificação da lipólise. O encapsulamento de cafeína em nanocosméticos à base de gel tem o objetivo de levar esse ativo até o adipócito, a célula alvo, para o tratamento de disfunções mencionado. Assim, objetivamos apresentar uma revisão de como tem sido o uso de cafeína na produção de cosméticos.

Quality of cosmetics with active caffeine in cream and gel galenic bases prepared by compounding pharmacies

Abstract As there is a great scarcity of studies on the importance of good compounding practices in the preparation of cosmetics, this study aimed to evaluate the quality control of cosmetics with active ingredient caffeine for the treatment of cellulite prepared by magistrals pharmacies. Microbiological analyzes, pH determination, color measurement, quantification of the percentage of the active ingredient caffeine and viscosity in creams and gels with 5% of the active ingredient caffeine were performed. In the microbiological analysis, the presence of molds and yeasts was verified above the permitted level according to the Brazilian pharmacopoeia. The pH decreased over time, contributing to the formulations becoming more acidic. In the color parameters, it was found that pharmacy F4 showed a brownish color, both for the gel and for the cream. The percentage of caffeine was within specifications in all formulations and the viscosity remained unchanged during the shelf life of the samples. It is important that the compounding pharmacies demand more effectively the commitment of the team, as well as the analysis of the raw material according to the microbiological control regulations to translate into the quality of the products prepared by the pharmacies and favor the consumer in the effective objective that the product you want to achieve.

Resumo Como há uma grande escassez de estudos sobre a importância de boas práticas de manipulação na elaboração de cosméticos, o presente estudo teve como objetivo avaliar o controle de qualidade de cosméticos com princípio ativo cafeína para o tratamento de celulite, elaborados por farmácias de manipulação de Campo Mourão. Foram realizadas análises microbiológicas, determinação do pH, mensuração da coloração, quantificação da porcentagem do princípio ativo cafeína e viscosidade em cremes e geís com 5% do princípio ativo cafeína. Nas análises microbiológicas foi verificada a presença de bolores e leveduras acima do pemitido segundo a farmacopéia brasileira. O pH diminuiu ao longo do tempo, contribuindo para que as formulações ficassem mais ácidas. Nos parâmetros de cor averiguou-se que a farmácia F4 apresentou uma coloração amarronzada, tanto para o gel quanto para o creme. A porcentagem de cafeína estava dentro das especificações em todas as formulações e a viscosidade se manteve inalterada durante o prazo de validade das amostras. Com o propósito de um melhor preparo magistral é importante que as farmácias de manipulação exijam de forma mais eficaz o comprometimento da equipe, bem como a análise da matéria-prima segundo as regulamentações de controle microbiológico. Além disso, a implementação de normas mais rígidas e o melhor controle da matéria-prima e das formulações finais fazem com que a qualidade dos produtos manipulados pelas farmácias magistrais seja aumentada significativamente, favorecendo o consumidor na efetiva finalidade a que o produto objetiva atingir.

Challenges of nanotechnology in cosmetic permeation with caffeine.

The evolution of beauty market and personal care is constant in Brazil as well in the rest of the world. Technological advances have brought up nanotechnology to the cosmetological field, employing active principles at atoms enveloped by vesicles, in order to take the active principle precisely to the target tissue to optimize the results achieved because of the considerable ease to cross skin barriers. Manufacturing of nanotechnology cosmetics is confronted with low absorption capacity. One of the many active principle found in cosmetic industry is caffeine, a pseudoalkaloid from the xanthine group used as a stimulant with the mechanism of the lipolytic action. This active is widely used in ​​a esthetics and cosmetics field in treatments involving dysfunctions such as localized fat and fibroedema geloid. To work out perfectly, the principle active need to interact and create a set of factors that includes lipolysis intensification. The caffeine encapsulation in gel-based nanocosmetics has the purpose of taking this active up to the adipocyte, the target cell, for mentioned dysfunctions treatment. Thus, we aim to present a review of how has been, the use of caffeine in the production of cosmetics.

Quality of cosmetics with active caffeine in cream and gel galenic bases prepared by compounding pharmacies.

As there is a great scarcity of studies on the importance of good compounding practices in the preparation of cosmetics, this study aimed to evaluate the quality control of cosmetics with active ingredient caffeine for the treatment of cellulite prepared by magistrals pharmacies. Microbiological analyzes, pH determination, color measurement, quantification of the percentage of the active ingredient caffeine and viscosity in creams and gels with 5% of the active ingredient caffeine were performed. In the microbiological analysis, the presence of molds and yeasts was verified above the permitted level according to the Brazilian pharmacopoeia. The pH decreased over time, contributing to the formulations becoming more acidic. In the color parameters, it was found that pharmacy F4 showed a brownish color, both for the gel and for the cream. The percentage of caffeine was within specifications in all formulations and the viscosity remained unchanged during the shelf life of the samples. It is important that the compounding pharmacies demand more effectively the commitment of the team, as well as the analysis of the raw material according to the microbiological control regulations to translate into the quality of the products prepared by the pharmacies and favor the consumer in the effective objective that the product you want to achieve.

Multicentre evaluation of a direct agglutination test prototype kit (DAT-LPC) for diagnosis of visceral leishmaniasis.

In this study, we assessed the sensitivity, specificity, and diagnostic accuracy of a previously developed direct agglutination test (DAT) using a freeze-dried antigen derived from Leishmania infantum promastigotes and composed in a prototype kit for visceral leishmaniasis (VL) diagnosis, named DAT-LPC. To evaluate DAT-LPC reproducibility, the kit was used to analyse 207 serum samples from VL patients and 80 serum samples from patients with other parasitic infections or healthy subjects in four laboratories from different public health institutions in Brazil. DAT-LPC showed sensitivity between 96·2 and 99·5% (P = 0·14), specificity ranging from 96·2 to 97·5% (P = 0·95), and diagnostic accuracy ranging from 96·5 to 99% (P = 0·34). The inter-laboratory reproducibility of qualitative results was classified as excellent (κ index: 0·94-0·97). The reproducibility of the end-titre results in relation to the reference laboratory, ranged from 31 to 85%. These results demonstrate an excellent performance of the DAT-LPC, and validate it for the diagnosis of VL that could replace the immunofluorescent antibody test as the routine diagnostic test in the Brazilian public health system.

A bacteriophage detection tool for viability assessment of Salmonella cells.

Salmonellosis, one of the most common food and water-borne diseases, has a major global health and economic impact. Salmonella cells present high infection rates, persistence over inauspicious conditions and the potential to preserve virulence in dormant states when cells are viable but non-culturable (VBNC). These facts are challenging for current detection methods. Culture methods lack the capacity to detect VBNC cells, while biomolecular methods (e.g. DNA- or protein-based) hardly distinguish between dead innocuous cells and their viable lethal counterparts. This work presents and validates a novel bacteriophage (phage)-based microbial detection tool to detect and assess Salmonella viability. Salmonella Enteritidis cells in a VBNC physiological state were evaluated by cell culture, flow-cytometry and epifluorescence microscopy, and further assayed with a biosensor platform. Free PVP-SE1 phages in solution showed the ability to recognize VBNC cells, with no lysis induction, in contrast to the minor recognition of heat-killed cells. This ability was confirmed for immobilized phages on gold surfaces, where the phage detection signal follows the same trend of the concentration of viable plus VBNC cells in the sample. The phage probe was then tested in a magnetoresistive biosensor platform allowing the quantitative detection and discrimination of viable and VBNC cells from dead cells, with high sensitivity. Signals arising from 3 to 4 cells per sensor were recorded. In comparison to a polyclonal antibody that does not distinguish viable from dead cells, the phage selectivity in cell recognition minimizes false-negative and false-positive results often associated with most detection methods.

Quantitative biomolecular sensing station based on magnetoresistive patterned arrays.

The combination of magnetoresistive sensors and magnetic labeling of bioanalytes, which are selectively captured by their complementary antibody in the proximity of the sensor is a powerful method in order to attain truly quantitative immunological assays. In this paper we present a technical solution to exploit the existing spin valve technology to readout magnetic signals of bio-functionalized magnetic nanoparticles. The method is simple and reliable, and it is based on a discrete scan of lateral flow strips with a precise control of the contact force between sensor and sample. It is shown that the signal of the sensor is proportional to the local magnetization produced by the nanoparticles in a wide range of concentrations, and the sensitivity thresholds in both calibration samples and real immunorecognition assays of human chorionic gonadotropin hormone are well below the visual inspection limit (5.5 ng/ml). Furthermore the sample scanning approach and the reduced dimensions of the sensors provide unprecedented spatial resolution of the nanoparticle distribution across the supporting nitrocellulose strip, therefore enabling on-stick control references and multi-analyte capability.

Spintronic platforms for biomedical applications.

Since the fundamental discovery of the giant magnetoresistance many spintronic devices have been developed and implemented in our daily life (e.g. information storage and automotive industry). Lately, advances in the sensors technology (higher sensitivity, smaller size) have potentiated other applications, namely in the biological area, leading to the emergence of novel biomedical platforms. In particular the investigation of spintronics and its application to the development of magnetoresistive (MR) biomolecular and biomedical platforms are giving rise to a new class of biomedical diagnostic devices, suitable for bench top bioassays as well as point-of-care and point-of-use devices. Herein, integrated spintronic biochip platforms for diagnostic and cytometric applications, hybrid systems incorporating magnetoresistive sensors applied to neuroelectronic studies and biomedical imaging, namely magneto-encephalography and magneto-cardiography, are reviewed. Also lab-on-a-chip MR-based platforms to perform biological studies at the single molecule level are discussed. Overall the potential and main characteristics of such MR-based biomedical devices, comparing to the existing technologies while giving particular examples of targeted applications, are addressed.

Picomolar detection limit on a magnetoresistive biochip after optimization of a thiol-gold based surface chemistry.

The surface biochemistry plays a crucial role in the development of stable and reproducible bioanalytical devices. Very often, it represents the bottleneck of a successful integration of magnetoelectronic transducers with the biological receptors on its interface. Here is discussed how a thiolgold surface chemistry can be tailored and optimized in order to allow the biofunctionalization of a magnetoresistive biochip, preventing loss of viability by corrosion while improving its sensitivity. Two important parameters, type of buffer solution and salt concentration (globally ionic strength), were evaluated in the effectiveness of the sulfur-gold linkage and further influence on the biomolecular recognition between single stranded DNA molecules. A third, not less important variable under investigation was the blocking solution. Non-specific adsorption of magnetic labels to the sensing surface still is a major problem to be addressed. The effect of two well known blocking molecules (bovine serum albumin (BSA)) and thiolated polyethylene-glycol (SH-PEG)) on the prevention of non-specific adsorption of targets and labels are compared. The best conditions were selected using an optical microscopic characterization method. Optical images were analyzed for magnetic particles quantification and results presented as a percentage of surface coverage. The optimized protocol was further implemented on real magnetoresistive devices to assess its electric compatibility and bioassay performance. A good reproducibility (about 9% error) among different devices measuring the same target concentration was achieved. Also a reduced non-specific binding signal of 43 microV for non-complementary targets (30% complementarity) compares with a 500 microV for fully complementarity. A linear range on the biological detection of magnetically labeled target ssDNA oligonucleotides is demonstrated. Consequently, the limit of detection at the standard operational conditions of the device is situated at the picomolar range.

Femtomolar limit of detection with a magnetoresistive biochip.

In this paper the biological limit of detection of a spin-valve-based magnetoresistive biochip applied to the detection of 20 mer ssDNA hybridization events is presented. Two reactional variables and their impact on the biomolecular recognition efficiency are discussed. Both the influence of a 250 nm diameter magnetic particle attached to the target molecule during the hybridization event and the effect of a magnetic focusing system in the hybridization of pre-labeled target DNA (assisted hybridization) are addressed. The particles carrying the target molecules are attracted to the probe active sensor sites by applying a 40 mA DC current on U-shaped aluminium current lines. Experiments comparing pre-hybridization versus post-hybridization magnetic labeling and passive versus magnetically assisted hybridization were conducted. The efficiency of a passive hybridization is reduced by about 50% when constrained to the operational conditions (sample volume, reaction time, temperature and magnetic label) of an on-chip real-time hybridization assay. This reduction has shown to be constant and independent from the initial target concentration. Conversely, the presence of the magnetic label improved the limit of detection when a magnetically assisted hybridization was performed. The use of a labeled target focusing system has permitted a gain of three orders of magnitude (from 1 pM down to 1 fM) in the sensitivity of the device, as compared with passive, diffusion-controlled hybridization.