Tuberculosis (TB) is one of the leading causes of infection in humans, causing high morbility and mortality all over the world. The rate of new cases of multidrug resistant tuberculosis (MDRTB) continues to increase, and since these infections are very difficult to manage, they constitute a serious health problem. In most cases, drug resistance in Mycobacterium tuberculosis has been related to mutations in several loci within the pathogen's genome. The development of fast, cheap and simple screening methodologies would be of paramount relevance for the early detection of these mutations, essential for the timely and effective diagnosis and management of MDRTB patients. The use of gold nanoparticles derivatized with thiol-modified oligonucleotides (Au-nanoprobes) has led to new approaches in molecular diagnostics. Based on the differential non-cross-linking aggregation of Au-nanoprobes, we were able to develop a colorimetric method for the detection of specific sequences and to apply this approach to pathogen identification and single base mutations/single nucleotide polymorphisms (SNP) discrimination. Here we report on the development of Au-nanoprobes for the specific identification of SNPs within the beta subunit of the RNA polymerase (rpoB locus), responsible for resistance to rifampicin in over 95% of rifampicin resistant M. tuberculosis strains.

A dye sensitized TiO2 photodetector has been integrated with a DNA detection method based on non-cross-linking hybridization of DNA-functionalized gold nanoparticles, resulting in a disposable colorimetric biosensor. We present a new approach for the fabrication of dye sensitized TiO2 photodetectors by an inkjet printing technique-a non-contact digital, additive, no mask and no vacuum patterning method, ideal for cost efficient mass production. The developed biosensor was compared against a dye sensitized photodetector fabricated by the traditional {"}doctor blade{"} method. Detection of gold nanoparticle aggregation was possible for concentrations as low as 1.0 nM for the {"}doctor blade{"} system, and 1.5 nM for the inkjet printed photodetector. The demonstrated sensitivity limits of developed biosensors; are comparable to those of spectrophotometric techniques (1.0 nM). Our results show that a difference higher than 17% by traditional photodetector and 6% by inkjet printed in the photoresponses for the complementary and non-complementary gold nanoprobe assays could be attained for a specific DNA sequence from Mycobacterium tuberculosis, the etiologic agent of human tuberculosis. The decrease of costs associated with molecular diagnostic provided by a platform such as the one presented here may prove of paramount importance in developing countries. (C) 2009 Elsevier B.V. All rights reserved.

The present invention relates to a system and process for detection and/or qualitative and quantitative identification of the biological material, such as specific sequences of nucleic acids or proteins as antibodies, present in biological samples. The system is composed by one or more light sources (1) combined with one or more integrated optical photo sensors, or not, and various electronic components (4), necessary for obtaining/processing of the signal emitted by the metal nanoprobes functionalized with a solution of biological composite, as well as also a micro-controller and a microprocessor, fixed or portable. This photosensor structure is able to detect and to quantify the colour variations produced by metal nanoprobes, being this preferentially gold, functionalized by oligonucleotides complementary to specific DNA/RNA sequences, proteins, as for instance antibodies and/or antigens related with certain disease, or other sample or solution of biological composite, that are to be investigated. The detection and quantification process is based on the response of a photosensor, singular or integrated, based on thin film technology of amorphous, nanocrystalline or microcrystalline silicon and their alloys, as well as the new active ceramic semiconductors, amorphous and not amorphous.

The present invention relates to a system and process for detection and/or qualitative and quantitative identification of the biological material, such as specific sequences of nucleic acids or proteins as antibodies, present in biological samples. The system is composed by one or more light sources (1) combined with one or more integrated optical photo sensors, or not, and various electronic components (4), necessary for obtaining/ processing of the signal emitted by the metal nanoprobes functionalized with a solution of biological composite, as well as also a micro-controller and a microprocessor, fixed or portable. This photosensor structure is able to detect and to quantify the colour variations produced by metal nanoprobes, being this preferentially gold, functionalized by oligonucleotides complementary to specific DNA/RNA sequences, proteins, as for instance antibodies and/or antigens related with certain disease, or other sample or solution of biological composite, that are to be investigated. The detection and quantification process is based on the response of a photosensor, singular or integrated, based on thin film technology of amorphous, nanocrystalline or microcrystalline silicon and their alloys, as well as the new active ceramic semiconductors, amorphous and not amorphous.

This paper describes a novel colorimetric method for detection of nucleic acid targets in a homogeneous format with improved sensitivity by means of a system based on the combination of a tunable monochromatic light source and an amorphous/nanocrystalline silicon photodetector that detects color and light intensity changes undergone by samples/assays containing tailored gold nanoparticles probes. This new low cost, portable, fast and simple optoelectronic platform, with the possibility to be re-used, permits detection of at least 400 fentomole of specific DNA sequences without target or signal amplification and was applied to the rapid detection of human pathogens in large variety of clinical samples such as Mycobacterium tuberculosis.

The present invention relates to a system and process for detection and/or qualitative and quantitative identification of the biological material, such as specific sequences of nucleic acids or proteins as antibodies, present in biological samples. The system is composed by one or more light sources (1) combined with one or more integrated optical photo sensors, or not, and various electronic components (4), necessary for obtaining/ processing of the signal emitted by the metal nanoprobes functionalized with a solution of biological composite, as well as also a micro-controller and a microprocessor, fixed or portable. This photosensor structure is able to detect and to quantify the colour variations produced by metal nanoprobes, being this preferentially gold, functionalized by oligonucleotides complementary to specific DNA/RNA sequences, proteins, as for instance antibodies and/or antigens related with certain disease, or other sample or solution of biological composite, that are to be investigated. The detection and quantification process is based on the response of a photosensor, singular or integrated, based on thin film technology of amorphous, nanocrystalline or microcrystalline silicon and their alloys, as well as the new active ceramic semiconductors, amorphous and not amorphous.

O presente invento relaciona-se com um novo sistema e processo para detec{\c c}ão e/ou identifica{\c c}ão qualitativa e quantitativa de matéria biológica, tais como sequências específicas de ácidos nucleicos ou proteínas, como anticorpos, presentes em amostras biológicas. O sistema é constituído por uma ou mais fontes luminosas combinadas, com um ou mais fotossensores ópticos integrados, ou não, e componentes electrónicos vários, necessários para obten{\c c}ão/condicionamento do sinal emitido por nanossondas de metal funcionalizadas com a solu{\c c}ão de composto biológico, bem como ainda um micro-controlador e um microprocessador, portável ou fixo. Este fotossensor é capaz de detectar e quantificar as diferen{\c c}as colorimétricas produzidas por nanossondas de metal, sendo este preferencialmente o ouro, funcionalizadas por oligonucleotídeos complementares às sequências específicas de ADN/ARN, proteínas, como por exemplo anticorpos e/ou antigénios relacionados com determinada doen{\c c}a, ou outra amostra ou solu{\c c}ão de composto biológico, que se pretende pesquisar. O processo de detec{\c c}ão e quantifica{\c c}ão baseia-se na resposta de um fotossensor, singular ou integrado, baseado na tecnologia de filmes finos de sílicio amorfo, nanocristalino ou mícrocristalino, e suas ligas, e também nos novos cerâmicos semicondutores activos, amorfos e não morfos. O referido sistema e processo de detec{\c c}ão e/ou identifica{\c c}ão de matéria biológica tem aplica{\c c}ão na biotecnologia, incluindo a biomedicina.

The impact of advances in nanotechnology is particularly relevant in biodiagnostics, where nanoparticle-based assays have been developed for specific detection of bioanalytes of clinical interest. Gold nanoparticles show easily tuned physical properties, including unique optical properties, robustness, and high surface areas, making them ideal candidates for developing biomarker platforms. Modulation of these physicochemical properties can be easily achieved by adequate synthetic strategies and give gold nanoparticles advantages over conventional detection methods currently used in clinical diagnostics. The surface of gold nanoparticles can be tailored by ligand functionalization to selectively bind biomarkers. Thiol-linking of DNA and chemical functionalization of gold nanoparticles for specific protein/antibody binding are the most common approaches. Simple and inexpensive methods based on these bio-nanoprobes were initially applied for detection of specific DNA sequences and are presently being expanded to clinical diagnosis.

Amorphous/nanocrystalline silicon pi'ii'n devices fabricated on micromachined glass substrates are integrated with oligonucleotide-derivatized gold nanoparticles for a colorimetric detection method. The method enables the specific detection and quantification of unamplified nucleic acid sequences (DNA and RNA) without the need to functionalize the glass surface, allowing for resolution of single nucleotide differences between DNA and RNA sequences-single nucleotide polymorphism and mutation detection. The detector's substrate is glass and the sample is directly applied on the back side of the biosensor, ensuring a direct optical coupling of the assays with a concomitant maximum photon capture and the possibility to reuse the sensor. (c) 2007 American Institute of Physics.