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Item type:Publication, Development of a label-free-SERS gold nanoaptasensor for the accessible determination of ochratoxin A(Elsevier, 2020-06-01)Nanomaterials use in traditional spectroscopic assays has enabled the development of more sensitive and accessible methods with wider-range of applications. Usually, the sensitivity of nanosensors is improved through the incorporation of labels or by inducing nanoparticles aggregation. Herein, we present the development of a label-free, selective, reliable, and affordable gold nanoprisms aptasensor to detect the content of ochratoxin A (OTA) in suspension by surface-enhanced Raman spectroscopy (SERS). Label-free SERS provides a molecular signature of the aptamer-OTA complex used and enables to discriminate OTA solutions from 10 to 250 ppb (25–620 nM) with multivariate analysis. This label-free nanoaptasensing system represents a new possibility for simpler and more reliable and accessible procedures for OTA determination. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Fabrication of Sub-10-nm Plasmonic Gaps for Ultra-Sensitive Raman Spectroscopy(Springer, 2020-08-01)The past two decades have witnessed the explosion of activities in the field of surface enhanced Raman spectroscopy (SERS). SERS platforms employ nano-structures that excite plasmonic modes with large local electromagnetic fields localized within small gap spaces between each constituting feature. Although the research-oriented SERS platforms yield significant signal enhancements to identify even single molecules, practical SERS-based sensors have not been fully introduced yet. The main reason behind this absence is the need for a cost-effective and reliable manufacturing method for controllable fabrication of plasmonic nano-gaps over large areas. In this article, we introduced a novel manufacturing process that enables fast and scalable fabrication of highly uniform sub-10-nm gaps that could yield large SERS signals. In this process, a conventional electroplating technique is used to produce unique nano-mushroom antenna arrays on a conducting substrate, resulting in controllable gap spaces between mushroom heads. By understanding the nature of mushroom shape antenna formation, we demonstrated the control of inter-metallic gaps down to 5 nm. We showed that the manufactured nano-structures yield Raman enhancements more than 108. Providing such large SERS signals that are uniform over large areas, our cost-effective fabrication technique could be very critical to realize practical SERS devices. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Development of an ochratoxin detection system by a microplate-based nanoaptasensor(Universidad Nacional de Trujillo, 2021-07-12)La ocratoxina A (OTA) es una micotoxina altamente tóxica producida por algunas variedades de hongos, capaz de contaminar productos agroindustriales, lo que ha obligado a establecer normas de regulación en varios países. Por tal motivo, es necesario contar con métodos confiables y sensibles para su detección temprana, que puedan ser utilizados de manera rutinaria. Los nanosensores aptaméricos representan una alternativa que puede mejorar la detección de moléculas de interés, debido a la alta afinidad y selectividad de los biorreceptores aptaméricos por objetivos específicos. Además, el uso de nanomateriales de metales nobles permite desarrollar sensores a partir de sus propiedades ópticas, como la resonancia de plasmón superficial localizado (LSPR), al poder monitorear los cambios en la superficie y relacionarlo con la concentración de una sustancia de interés. En este trabajo se muestran los avances en el desarrollo de un sistema alternativo de detección de OTA basado en nanosensores aptaméricos. El procedimiento contempla la síntesis y funcionalización de nanoesferas de oro (AuNEs) con un aptámero selectivo a OTA (APT), el proceso de modificación de microplacas con la hebra complementaria a dicho aptámero (HC) y la hibridación entre los oligonucleótidos conjugados. Finalmente, a modo de prueba de concepto, se realizaron algunas pruebas que permitieron discriminar la presencia de 336 ppb de OTA. Palabras clave: Aptámeros, micotoxinas, microplacas, nanosensores, ocratoxina A, oro. Ochratoxin A (OTA) is a highly toxic mycotoxin produced by some varieties of fungi, capable of contaminating agro-industrial products, this has forced the establishment of regulatory standards in several countries. Therefore, it is required to have reliable and sensitive methods for its early detection that could be implemented in routine assays. Aptameric nanosensors are an alternative method that can improve the detection of specific target molecules, due to the high affinity and selectivity of aptameric bioreceptors for specific targets. In addition, the use of noble metal nanomaterials allows the development of sensors based on their optical properties such as localized surface plasmon (LSPR), as it is possible to monitor changes in their surface and relate them to the concentration of a target analyte. This work has focused in the development of an alternative OTA detection system, based on aptameric nanosensors. The procedure contemplates the synthesis and functionalization of gold nanospheres (AuNEs) with an OTA-selective aptamer (APT), a microplate surface modification procedure with the complementary strand to the aptamer (HC) and the hybridization between the oligonucleotides. Lastly, as a proof of concept, some assays were performed to discriminate the presence of 336 ppb of OTA. Keywords: Aptamers, gold, microplates, mycotoxins, nanosensors, ochratoxin A. *Autor para correspondencia: E. mail: bgalarreta@pucp.pe DOI: http://dx.doi.org/10.17268/rebiol.2021.41.01.03 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, El potencial de la nanotecnología para evitar que el SARS-CoV-2 ingrese a nuestro organismo(2021-07-01)Nos encontramos en una carrera mundial contra la pandemia de COVID-19, una enfermedad infecciosa ocasionada por el virus respiratorio SARS-Cov-2. En este contexto, representan una atractiva alternativa para combatir el virus las propiedades fisicoquímicas de la nanotecnología. En este artículo, se presenta una breve revisión de las distintas herramientas nanotecnológicas desarrolladas para la desactivación del SARS-CoV-2 y evitar que ingrese a nuestro organismo, mediante su aplicación en equipos de protección personal, superficies inanimadas y sistemas de filtros. Una mejor comprensión de su funcionamiento y de las ventajas que ofrecen son claves para su posible implementación en el Perú. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Survey of the undergraduate analytical chemistry curriculum(American Chemical Society, 2022-06-14)This article reports the results of a curriculum survey of 322 analytical chemistry instructors (92% U.S.-based) conducted during Spring 2021. This snapshot of current course formats, topics, and pedagogical methods will be useful to both seasoned and novice teachers of analytical chemistry. The majority of respondents reported that their major requires two analytical chemistry courses, and 97% of respondents reported that at least one analytical course is required. Over 80% reported a required analytical lab course. The topic rated most important was standardization and calibration methods, followed by UV-vis absorbance spectroscopy, data handling, HPLC, GC, statistical analysis, general chromatographic theory, sources and types of error, mass spectrometry, and acid-base theory/equilibria/buffers. In general, topics that were rated as important were likely to be taught in required courses and addressed in hands-on laboratories. Over 80% of instructors reported the use of at least one evidence-based active learning strategy. In response to open-ended questions, instructors shared their strategies for student career preparation, project-based learning, and inclusive teaching, with these responses summarized using thematic analysis. Responses from 117 instructors give a snapshot of current efforts to promote diversity, equity, and inclusion, including cultivation of an inclusive environment, implementation of active learning, and examples of diverse scientists and culturally relevant examples. Respondents also reported the biggest challenge to their teaching, which was most frequently associated with obtaining and maintaining instrumentation. The results of this survey will help inform curricular updates in individual courses and programs and may inspire larger community-wide efforts to improve undergraduate analytical instruction. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Tailored peptide nanomaterials for receptor-targeted prostate cancer imaging(Royal Society of Chemistry, 2024-11-05)We report the development of a peptide-based optical nanoprobe specifically tailored for prostate cancer imaging. The imaging probe is comprised of cyclic peptide nanotubes, formed via the aqueous co-assembly of four cyclic D,L-alternating octapeptides. The inherent properties of these cyclic building blocks have been carefully selected to enhance their efficacy in imaging applications, through the addition of a cancer targeting peptide and a fluorescent dye. Comprehensive characterization using scanning electron microscopy (FESEM) and low-voltage transmission electron microscopy (LV-TEM) confirms the formation of nanotubes through co-assembly of the cyclic peptides. The resulting nanotubes show an average diameter of 28 nm. Circular dichroism (CD) spectroscopy validates the formation of stable beta-sheet hydrogen bonding structures at both 20 and 37 °C, ensuring their suitability for biomedical applications. Evaluation of PSMA-binding specificity of the resulting peptide nanotubes is assessed using confocal fluorescence microscopy demonstrating receptor-mediated uptake in prostate cancer cells. We anticipate this strategy will provide the basis for the utilization of co-assembled systems for advancing molecular imaging techniques in prostate cancer and other cancers.4 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Exploring the modelling of gold anisotropic nanoparticles’ optical properties as a promising tool for detection systems design(Multidisciplinary Digital Publishing Institute (MDPI), 2024-12-01)Gold nanoparticles have been a central topic in the last few decades due to their excellent optical properties that can be exploited in many applications, including food analysis, materials science, and biomedicine. The basis of these unique optical properties is the phenomenon known as localized surface plasmon (LSP), which relays in the collective oscillation of the conduction band electrons in the nanoparticle when excited by electromagnetic radiation. The optical properties of the nanoparticles are critical for selecting the best nanomaterials for each application, a key factor for optimum performance, and can be tuned due to their dependence on the geometry and size of the nanoparticles, as well as the polarization of the light beam. Here, we conducted simulations to study the tunable optical properties and local electric field distribution of three types of gold nanoparticles, cubes (AuNC), boxes (AuNB), and triangular prisms (AuNT), which have relatively simple synthetic routes. Finally, we compared these results with experimental data and described possible synthetic routes to discuss the positive and negative aspects of using each type of nanoparticle for potential applications.1 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Incorporation of analytical chemistry in the undergraduate curriculum: Examples from different regions of the world(Springer Science and Business Media Deutschland GmbH, 2024-07-01)Graphical (Figure presented.) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Three-Dimensional Membranes of Natural Polymer Complex Nanoparticle for Potential Medical Applications(Multidisciplinary Digital Publishing Institute (MDPI), 2023-11-01)Skin wound healing is a complex biological process of tissue regeneration in which the wound dressing is crucial for rapid healing; it must protect the wound keep an adequate level of moisture and prevent infections. Alginate (AL), a polysaccharide from brown algae, has been extensively studied for wound treatment, and aloe vera gels (AVGs) have also been used in the treatment of skin. The AVG main bioactive polysaccharide was combined with AL for the preparation of membranes. Two-dimensional membranes were prepared by casting and, for comparison, transparent nanoparticle 3D membranes were produced by high-intensity ultrasonication followed by ionotropic crosslinking. The effects of the amount of AVG, ionotropic gelation, and the structure (2D or 3D) of the AL-AVG membranes were compared. Scanning electron microscopy (SEM) showed higher surface roughness on 3D membranes. Three-dimensional membranes showed a higher swelling ratio, and swelling increased with AVG content and decreased with higher calcium concentration and longer gelation times. The degradation of the membranes was evaluated with and without a lysozyme at pH 5.5, 7.5, and 8.5, to simulate different skin conditions; the results evidence that pH had a higher effect than the enzyme. The cytotoxicity of the membranes was evaluated with ATCC CCL 163 and ATCC CCL 81 cells, and an excellent biocompatibility of both cell types (>90% of cell viability after 48 h incubation) was observed for all AL-AVG membranes. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Nanosensor for carcinoembryonic antigen (CEA) detection based on a selective growth-regulating mechanism(Elsevier BV, 2025-01-01)Nanomaterial-based biosensors provide high sensitivity and versatility for the detection of target analytes. Particularly, gold nanomaterials are widely employed as signal transducers due to their unique plasmonic properties. When functionalized with aptamers, these nanostructures gain enhanced selectivity, rapid response capability, and cost-effectiveness. However, the instability of large gold nanoparticles can hinder the exploration of various shapes and sizes. In this research, two different types of nanoparticles were used for the development of a carcinoembryonic antigen (CEA), a tumoral biomarker for colorectal cancer, nanosensor. It was proposed a system based on gold nanotriangles (AuNTs) functionalized with the amphiphilic polymer polyvinylpyrrolidone (AuNT@PVP) and a hairpin-shaped aptamer selective to CEA biotinylated at the 3' end and thiolated at the 5' end (AuNT@PVP@Apt). Specific recognition process was optimized expecting that CEA would trigger the unfolding of the hairpin structure, exposing biotin moieties that enabled subsequent binding of streptavidin-functionalized gold nanoparticles (AuNP@Strept, 3-5 nm in diameter). However, when analyzing the optical changes observed by UV-Vis-NIR spectroscopy and its correlation with the concentration of CEA, it was observed that the main mechanism involved in the detection was a selective growth mechanism of AuNPs, leading to a really simple and easy way of detecting CEA. The results obtained in this study highlight the intricacies of developing such nanosensors and introduce a novel detection method based on a selective growth mechanism that can be further used for detection.1