Oriented Tailoring of Plastic Antibodies for Prostate Specific Antigen and Application of the Imprinted Material as Ionophore in Potentiometric Detection

Poster, presented at Nanobio Europe, Varese, Italy, 18 - 20 June, 2012.Prostate Specific Antigen (PSA) is the biomarker of choice for screening prostate cancer throughout the population, with PSA values above 10 ng/mL pointing out a high probability of associated cancer1. According to the most recent World Health Organization (WHO) data, prostate cancer is the commonest form of cancer in men in Europe2. Early detection of prostate cancer is thus very important and is currently made by screening PSA in men over 45 years old, combined with other alterations in serum and urine parameters. PSA is a glycoprotein with a molecular mass of approximately 32 kDa consisting of one polypeptide chain, which is produced by the secretory epithelium of human prostate. Currently, the standard methods available for PSA screening are immunoassays like Enzyme-Linked Immunoabsorbent Assay (ELISA). These methods are highly sensitive and specific for the detection of PSA, but they require expensive laboratory facilities and high qualify personal resources. Other highly sensitive and specific methods for the detection of PSA have also become available and are in its majority immunobiosensors1,3-5, relying on antibodies. Less expensive methods producing quicker responses are thus needed, which may be achieved by synthesizing artificial antibodies by means of molecular imprinting techniques. These should also be coupled to simple and low cost devices, such as those of the potentiometric kind, one approach that has been proven successful6. Potentiometric sensors offer the advantage of selectivity and portability for use in point-of-care and have been widely recognized as potential analytical tools in this field. The inherent method is simple, precise, accurate and inexpensive regarding reagent consumption and equipment involved. Thus, this work proposes a new plastic antibody for PSA, designed over the surface of graphene layers extracted from graphite. Charged monomers were used to enable an oriented tailoring of the PSA rebinding sites. Uncharged monomers were used as control. These materials were used as ionophores in conventional solid-contact graphite electrodes. The obtained results showed that the imprinted materials displayed a selective response to PSA. The electrodes with charged monomers showed a more stable and sensitive response, with an average slope of -44.2 mV/decade and a detection limit of 5.8X10-11 mol/L (2 ng/mL). The corresponding non-imprinted sensors showed smaller sensitivity, with average slopes of -24.8 mV/decade. The best sensors were successfully applied to the analysis of serum samples, with percentage recoveries of 106.5% and relatives errors of 6.5%

Coleobrocas em acessos do banco de germoplasma de mandioca da Embrapa Amazônia Oriental.

A mandioca (Manihot esculenta Crantz) é uma planta cultivada em todas as regiões do Brasil, com destaque para o estado do Pará, maior produtor nacional. A cultura está sujeita ao ataque de pragas durante todo o seu ciclo. As brocas da haste, consideradas pragas secundárias, penetram na haste debilitando a planta. O objetivo desse trabalho foi avaliar os acessos do banco de germoplasma de mandioca da Embrapa Amazônia Oriental quanto à presença de brocas da haste considerando a ocorrência dessa praga em plantas de mandioca açucarada e que o dano ocasionado pelo inseto pode se constituir em uma porta de entrada para patógenos. Foram realizadas avaliações mensais, com a identificação e coleta das plantas com aspecto de murcha e/ou com perfurações nas hastes. Foram constatadas 61 plantas com aspecto de murcha, distribuídas em 45 acessos. Destas, 51 plantas apresentaram hastes com galerias na região do colo e na parte superior da planta. Foram coletadas 79 larvas pertencentes aos tipos carabiforme, curculioniforme e limaciforme. Foram obtidos 176 adultos pertencentes à ordem Coleoptera e às famílias Cerambycidae (Anisopodus lignicola Bates, 1863) e Curculionidae (Pappista granicollis (Pierce, 1916))