SERS active colloidal nanoparticles for the detection of small blood biomarkers using aptamers

Functionalized colloidal nanoparticles for SERS serve as a promising multifunctional assay component for blood biomarker detection. Proper design of these nanoprobes through conjugation to spectral tags, protective polymers, and sensing ligands can provide experimental control over the sensitivity, range, reproducibility, particle stability, and integration with biorecognition assays. Additionally, the optical properties and degree of electromagnetic SERS signal enhancement can be altered and monitored through tuning the nanoparticle shape, size, material and the colloid's local surface plasmon resonance (LSPR). Aptamers, synthetic affinity ligands derived from nucleic acids, provide a number of advantages for biorecognition of small molecules and toxins with low immunogenicity. DNA aptamers are simpler and more economical to produce at large scale, are capable of greater specificity and affinity than antibodies, are easily tailored to specific functional groups, can be used to tune inter-particle distance and shift the LSPR, and their intrinsic negative charge can be utilized for additional particle stability.1,2 Herein, a "turn-off" competitive binding assay platform involving two different plasmonic nanoparticles for the detection of the toxin bisphenol A (BPA) using SERS is presented. A derivative of the toxin is immobilized onto a silver coated magnetic nanoparticle (Ag@MNP), and a second solid silver nanoparticle (AgNP) is functionalized with the BPA aptamer and a Raman reporter molecule (RRM). The capture (Ag@MNP) and probe (AgNP) particles are mixed and the aptamer binding interaction draws the nanoparticles closer together, forming an assembly that results in an increased SERS signal intensity. This aptamer mediated assembly of the two nanoparticles results in a 100x enhancement of the SERS signal intensity from the RRM. These pre-bound aptamer/nanoparticle conjugates were then exposed to BPA in free solution and the competitive binding event was monitored by the decrease in SERS intensity

Evolución del diseño de interiores en los grandes Centros Comerciales de Lima Central Sur en las últimas tres décadas

La investigación responde a una problemática que se evidencia a través de una serie de debilidades que repercuten en el diseño de dichos centros comerciales. El conocimiento de nuevas tecnologías para el diseño interior era escaso, no había conocimientos de enchapes, acabados finos, iluminación decorativa y diseño interior en general. Los materiales tampoco eran de gran ayuda, solo se conocían las estructuras comunes, como el cemento y el acero. Tampoco había conocimientos sobre técnicas constructivas

Knowledge and attitude toward theranostics among Nuclear Medicine Technologists

This study was conducted to determine the knowledge and attitude of nuclear medicine technologists toward theranostics. This research utilized a quantitative correlational research design. Data were gathered from 69 practicing nuclear medicine technologists, specifically those that do not perform or have theranostics procedures. The data were gathered using a self-made questionnaire and statistically treated using frequency, percentage, range, mean, standard deviation, t-test, ANOVA, Kruskal-Wallis H test, Mann-Whitney U test, and Spearman Rank Order Correlation. Findings show that the majority of the respondents are male, and most are 20-30 years old. Most of the respondents have good knowledge and show a “positive attitude” toward theranostics. In general, there are no significant differences in the knowledge of the respondents about theranostics when they are grouped according to sex, years of experience and type of hospital they are currently employed in. However, there is a significant difference when grouped according to age, where the 31–40-year-old group showed a higher level of knowledge than the 20-30-year-old group possibly due to learning more about practices with theranostics. With the respondents’ attitude toward theranostics, there are no significant differences when they are grouped according to age, sex, years of experience, and type of hospital they are currently employed in. The findings also show that there is a weak positive relationship between the knowledge and attitude of the respondents toward theranostics. Generally, the results show that nuclear medicine technologists have very good attitude toward and good knowledge of theranostics

Detection of cardiovascular disease associated miR-29a using paper-based microfluidics and surface enhanced Raman scattering

Detection of miR-29a-3p, a microRNA associated with myocardial infarction, was achieved at a level of pg/L through the combination of three-dimensional paper-based microfluidics, colorimetric detection, and surface enhanced Raman scattering (SERS) analysis. The union of the paper-based device and the two analysis methods resulted in the production of a sensitive, reproducible and facile, point of care test (POCT), which paves the way for future implementation in the diagnosis of a range of diseases

Development of a robust optical glucose sensor

The long term objective of this research was the development of a noninvasive, optically-based, polarimetric sensor to monitor in vivo glucose concentrations. The goal of diabetes therapy is to approximate the 24-hour blood glucose profile of a normal individual. There have been major advances in the development of reliable, versatile, and accurate pumps for the delivery of insulin to diabetic patients and in the development of control algorithms for closed-loop insulin delivery, however, there remain major obstacles to the development of clinically useful, continuous glucose sensors. The development of an accurate noninvasive glucose sensor would have significant application in the diagnosis and management of diabetes mellitis both in conjunction with, and independent of, the glucose pump controller applications.^ The linear polarization vector of light routes when it interacts with an optically active material such as glucose. The amount of rotation of polarization is directly proportional to the glucose concentration and to the path length. The ability to quantitate blood glucose levels for the limited available path length in our primary sensing site, namely, the anterior chamber of the eye, therefore depends on the signal-to-noise ratio of the polarization detector.^ Our primary research focused on the development and testing of a prototype optical polarimetry system using D + glucose solution in a test cell, as well as using an enucleated human eye to assess the sensitivity of the system to measure physiologic glucose levels for the approximate one centimeter path length present in the anterior chamber of the eye. Our research has led to the development of a true phase technique in which helium neon laser light was coupled through a rotating linear polarizer along with two stationary linear polarizers and two detectors to produce reference and signal outputs whose amplitudes varied sinusoidally and whose phase was proportional to the rotation of light caused by the glucose solution.

Eye coupling mechanism for noninvasive glucose measurements with polarized light

Embodiments concern coupling polarized light at two or more wavelengths across the aqueous humor of the eye (e.g., as part of a noninvasive glucose monitoring system). An approach discloses non-contact and minimal contact eye-coupling designs that are part of a system for providing glucose concentration levels via measurements acquired by passing two or more optical beams through the cornea/aqueous chamber in the eye. The approach provides for coupling the light to account for the index mismatch incurred while allowing for monitoring the light polarization. Specifically, in an embodiment the light transitions from the device, through the air, through the proximal side of the cornea, through the aqueous humor, through the medial side of the cornea, and through the air back into the device. Embodiments address the index of refraction mismatch and polarized light maintaining concerns with a coupling approach that can take the form of contact and non-contact mechanisms.U

Overcoming the aggregation problem : a new type of fluorescent ligand for ConA-based glucose sensing

Competitive binding assays based on the lectin Concanavalin A (ConA) have displayed significant potential to serve in continuous glucose monitoring applications. However, to date, this type of fluorescent, affinity-based assay has yet to show the stable, glucose predictive capabilities that are required for such an application. This instability has been associated with the extensive crosslinking between traditionally-used fluorescent ligands (presenting multiple low-affinity moieties) and ConA (presenting multiple binding sites) in free solution. The work herein introduces the design and synthesis of a new type of fluorescent ligand that can avoid this aggregation and allow the assay to be sensitive across the physiologically relevant glucose concentration range. This fluorescent ligand (APTS-MT) presents a single high-affinity trimannose moiety that is recognized by ConA’s full binding site and a fluorophore that can effectively track the ligand’s equilibrium binding via fluorescent anisotropy. This is confirmed by comparing its measured fluorescent lifetime to experimentally-determined rotational correlation lifetimes of the free and bound populations. Using an assay comprised of 200 nM APTS-MT and 1 μM ConA, the fluorescence anisotropy capably tracks the concentration of monosaccharides that are known to bind to ConA’s primary binding site, and the assay displays a MARD of 6.5% across physiologically relevant glucose concentrations. Ultimately, this rationally-designed fluorescent ligand can facilitate the realization of the full potential of ConA-based glucose sensing assays and provide the basis for a new set of competing ligands to be paired with ConA