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- Dual-Mode Gold Nanoparticle-Based Method for Early Detection of AcanthamoebaPublication . Pastrana, Cristina; Guerreiro, Joana Rafaela; Elumalai, Monisha; Carpena-Torres, Carlos; A, Crooke; Carracedo Rodriguez, Juan Gonzalo; Prado, Marta; Toral, FernandoAcanthamoebakeratitis is an aggressive and rapidly progressing ocular pathology whosemain risk factor is the use of contact lenses. An early and differential diagnosis is considered themain factor to prevent the progression and improve the prognosis of the pathology. However, currentdiagnosis techniques require time, complex and costly materials making an early diagnosis challeng-ing. Thus, there is a need for fast, accessible, and accurate methods forAcanthamoebadetection bypractitioners for timely and suitable treatment and even for contact lens user as preventive diagnosis.Here, we developed a dual-mode colorimetric-based method for fast, visual, and accurate detectionofAcanthamoebausing gold nanoparticles (AuNPs). For this strategy, AuNPs were functionalizedwith thiolated probes and the presence of targetAcanthamoebagenomic sequences, produce a colori-metric change from red to purple. This approach allows the detection of 0.02 and 0.009μM of theunamplifiedAcanthamoebagenome by the naked eye in less than 20 min and by color analysis usinga smartphone. Additionally, real samples were successfully analyzed showing the potential of thetechnology considering the lack of point-of-care tools that are mostly needed.
- Encapsulation of Nanostructures in a Dielectric Matrix Providing Optical Enhancement in Ultrathin Solar CellsPublication . Oliveira, Antonio; de Wild, Jessica; Oliveira, Kevin; Valença, Beatriz A.; Guerreiro, Joana Rafaela; Abalde-Cela, Sara; Lopes, Tomás; Ribeiro, Rodrigo M.; Cunha, José Miguel; M.C.Alberto; Monteiro, Margarida; Violas, André; Silva, Ana Gomes; Prado, Marta; Fernandes, P. A.; Vermang, Bart; Salomé, P. M. P.The incorporation of nanostructures in optoelectronic devices for enhancing their optical performance is widely studied. However, several problems related to the processing complexity and the low performance of the nanostructures have hindered such actions in real-life devices. Herein, a novel way of introducing gold nanoparticles in a solar cell structure is proposed in which the nanostructures are encapsulated with a dielectric layer, shielding them from high temperatures and harsh growth processing conditions of the remaining device. Through optical simulations, an enhancement of the effective optical path length of approximately four times the nominal thickness of the absorber layer is verified with the new architecture. Furthermore, the proposed concept in a Cu(In,Ga)Se2 solar cell device is demonstrated, where the short-circuit current density is increased by 17.4%. The novel structure presented in this work is achieved by combining a bottom-up chemical approach of depositing the nanostructures with a top-down photolithographic process, which allows for an electrical contact.
- Automated lab-on-chip for the specific detection of invasive species through environmental DNAPublication . Elumalai, Monisha; Ipatov, Andrey; Guerreiro, Joana; Prado, MartaThe ability to detect nucleic acid sequences is revolutionizing the fast identification of specific organisms, particularly with Lab-on-a-chip systems. However, these often rely on complex processes, skilled personnel, and external control devices which limits automation. To address this, we present an automated, portable, and easyto-fabricate lab-on-chip that combines enzyme-assisted DNA signal amplification and optical detection for in-situ monitoring of zebra mussel invasive species in the environment. Zebra mussels DNA triggers enzyme-assisted signal amplification through hybridization, leading to a quantitative colorimetric response. The sensing performance exhibited enhanced sensitivity when increasing AuNPs diameter from 23.3 ± 1.6 to 67.4 ± 2.0 nm. Quantitative colorimetric approaches displayed an LoD of 0.5 pM, 19-fold increase in sensitivity when compared to naked eye. The system enabled to discriminate single nucleotide polymorphism (SNP) for concentrations from 130 pM and to successfully analyse Zebra mussel samples from the Guadalquivir River. Experiments were conducted by the user and an automated device. The accuracy was tested with a 60 pM sample which was pretreated externally and analysed by the automated system resulting in relative error of 16.8% and 13.4%, respectively. The automated system reduced the analysis time by 1 h and 20 min, great advantage for in-situ analysis.