Antibody-Capped Mesoporous Nanoscopic Materials: Design of a Probe for the Selective Chromo-Fluorogenic Detection of Finasteride

The synthesis of capped mesoporous silica nanoparticles (MSN) conjugated with an antibody (AB) as a gatekeeper has been carried out in order to obtain a delivery system able to release an entrapped cargo (dye) in the presence of a target molecule (antigen) to which the conjugated antibody binds selectively. In particular, MSN loaded with rhodamine B and functionalized on the external surface with a suitable derivative of N-(t-butyl)-3-oxo-(5α,17β)-4-aza-androst-1-ene-17-carboxamide (finasteride) have been prepared (S1). The addition of polyclonal antibodies against finasteride induced capping of the pores due to the interaction with the anchored hapten-like finasteride derivative to give a MSN–hapten–AB nanoparticle S1-AB. It was found that the addition of capped material S1-AB to water solutions containing finasteride resulted in displacement of the antibody, pore uncapping and entrapped-dye release. The response of the gated material is highly selective, and only finasteride, among other steroids, was able to induce a significant uncapping process. Compared with finasteride, the finasteride metabolite was able to release 17 % of the dye, whereas the exogen steroids testosterone, metenolone and 16-β-hydroxystanozolol only induced very little release of rhodamine B (lower than 10 %) from aqueous suspensions containing sensing solid S1-AB. A detection limit as low as 20 ppb was found for the fluorimetric detection of finasteride. In order to evaluate a possible application of the material for label-free detection of finasteride, the capped material was isolated and stored to give final sensing solid S1-AB-i. It was found to display a similar behavior towards finasteride as to that shown by freshly prepared S1-AB; even after a period of two months, no significant loss of selectivity or sensitivity was noted. Moreover, to study the application for the detection of finasteride in biological samples, this “aged” material, S1-AB-i, was tested using commercially available blank urine as matrix. Samples containing 70 and 90 % blank urine were spiked with a defined amount of finasteride, and the concentration was determined using capped S1-AB-i. Recovery ranges from 94 % to 118 % were reached.     

Estimation of the composition of recombinant human erythropoietin mixtures using capillary electrophoresis and multivariate calibration methods

A multivariate calibration method using partial least-squares (PLS) is proposed in order to characterize binary mixtures of two types of recombinant human erythropoietin (epoetin alpha and beta), based on the analysis of the highly overlapped UV-electrophoretic profiles obtained with the CE methodology recommended by the European Pharmacopoeia (EurPh). A two-factor PLS-1 model was developed and validated using mixtures of alpha and beta epoetins. Glycoforms were identified according to their effective electrophoretic mobility values and the normalized area values of each glycoform peak were used as multivariate data. Calibration and validation results were satisfactory. The PLS-1 model was successfully used for determination of epoetin alpha and beta contents in the rHuEPO provided by the EurPh as a biological reference product.     

The Effects of Supply on Mazzaella laminarioides (Rhodophyta,Gigartinales) from Southern Chile

The effects of nitrate supply on growth, pigments, mycosporine‐like amino acids (MAAs), C:N ratios and carrageenan yield were investigated in Mazzaella laminarioides cultivated under solar radiation. This species is economically important in southern Chile where an increase of nitrogen in coastal waters is expected as a consequence of salmon aquaculture activity. Apical segments were cultivated in enriched seawater with five different concentrations (0, 0.09, 0.18, 0.38 and 0.75 mm ) during 18 days. Although phycoerythrin and phycocyanin content, as well as C:N ratios, were reduced in the control treatment (without supply), when compared to treatments, total MAA concentration, carrageenan yield and growth rates were similar in all tested conditions. Nevertheless, during the experiment, an important synthesis of mycosporine‐glycine took place in a nitrate concentration‐dependent manner, with accumulation being saturated around 0.18 mm of nitrate. These results indicate that exposure to high concentration of more than 100 times the values observed in the nature did not impair the photoprotection system, as determined by MAAs, nor did it have a deleterious effect on growth or carrageenan yield of M. laminarioides, a late successional species from Chile.     

Reaction of Alkynes and Azides: Not Triazoles Through Copper–Acetylides but Oxazoles Through Copper–Nitrene Intermediates

Well‐defined copper(I) complexes of composition [Tpm*^,BrCu(NCMe)]BF₄ (Tpm*^,Br=tris(3,5‐dimethyl‐4‐bromo‐pyrazolyl)methane) or [Tpa^*Cu]PF₆ (Tpa^*=tris(3,5‐dimethyl‐pyrazolylmethyl)amine) catalyze the formation of 2,5‐disubstituted oxazoles from carbonyl azides and terminal alkynes in a direct manner. This process represents a novel procedure for the synthesis of this valuable heterocycle from readily available starting materials, leading exclusively to the 2,5‐isomer, attesting to a completely regioselective transformation. Experimental evidence and computational studies have allowed the proposal of a reaction mechanism based on the initial formation of a copper–acyl nitrene species, in contrast to the well‐known mechanism for the copper‐catalyzed alkyne and azide cycloaddition reactions (CuAAC) that is triggered by the formation of a copper–acetylide complex.     

Analysis of human transferrin glycopeptides by capillary electrophoresis and capillary liquid chromatography-mass spectrometry. Application to diagnosis of alcohol dependence

In this study, capillary electrophoresis and capillary liquid chromatography coupled to mass spectrometry (CE-TOF-MS and μLC-TOF-MS) were used to detect and characterise human transferrin (Tf) glycopeptide glycoforms obtained by tryptic digestion. After selecting μLC-TOF-MS because of improved performance in analysis of N₄₁₃ and N₆₁₁ glycopeptide glycoforms, the proposed methodology was applied to serum samples. Two immunoaffinity columns were employed to isolate Tf from serum samples. Both columns were activated with the same anti-Tf antibody but using two different bonding chemistries. After immunoaffinity purification and digestion, serum samples from a teetotal individual (as control) and from individuals with low and high alcohol dependence were analysed by μLC-TOF-MS. Relative abundance of each glycoform was useful to estimate the degree of alcohol dependence of each individual. Finally, the established methodology was used to analyse serum samples from specific individuals with an unknown degree of alcohol dependence.     

An Application of Capillary Electrophoresis for the Analysis of Algal Toxins from the Aquatic Environment

In this work capillary electrophoresis (CE) with UV detection has been applied to the analysis of different natural toxins produced in the aquatic environment. This technique is presented as an alternative to other chemical techniques such as HPLC, and the optimisation of analytical methodologies was carried out for diverse marine toxins including Paralytic and Amnesic and some polyether toxins, such as Yessotoxins, as well as for certain microcystin toxins produced by cyanobacteria present in freshwaters. Sample preparation steps were optimised and adequate electrophoretic conditions developed for achieving a complete separation of compounds with similar structures involved in such contamination. The influence of the biological matrices where they are involved has also been studied and the potential use of CE-UV as a tool for monitoring these aquatic toxins is also discussed.     

A natural selection from the core of a TU game: the core-center

We present a new allocation rule for the class of games with a nonempty core: the core-center. This allocation rule selects a centrally located point within the core of any such game. We provide a deep discussion of its main properties.     

Complex formation in Mn-doped GaP samples

It is known that Mn in n-type GaP undergoes complexation upon annealing at temperatures close to 1000° C. An investigation of the optical properties of annealed Mn-doped GaP is carried out by several techniques. Photoluminescence (PL) and time-resolved spectroscopy (TRS) are combined with lifetime measurements at different temperatures. A new broad photoluminescence band peaking at 2.03 eV at low temperatures is investigated. This band has the characteristics of a bound exciton and is interpreted as due to a nearest-neighbour Mn complex with a donor.     

Multisyringe ion chromatography with chemiluminescence detection for the determination of oxalate in beer and urine samples

The first multisyringe-based low-pressure ion chromatographic method is presented. It is based on the use of short surfactant coated octadecyl-silica monolithic columns. As a first application, we have determined oxalate in beer and human urine via post-column chemiluminescence detection. Oxalate is separated from the sample matrix in the monolithic column by precise programmable fluid handling, and then detected by reaction with on-line generated tris(2,2??-bipyridyl)ruthenium(III). Column coating, un-coating, ion chromatography and chemiluminescence detection are quickly performed by using a simple low-pressure multi-burette. The factors influencing the separation of oxalate and its subsequent detection, including the column coating with surfactants and its stability have been studied. The chromatographic behavior of the oxalate in presence of potentially interfering species also was assessed. The method has limits of detection and quantification of 0.025 and 0.035?mg?L^?1, respectively, a relative standard deviation of 3.1% (for 10 consecutive measurements without column re-coating) and a throughput of 48?h^?1. The results obtained with real samples were validated by using an enzymatic spectrophotometric test. The method is critically compared to recent methods for the determination of oxalate.

Band gap tuning of Cu(In,Ga)Se2 thin films by electrodeposition and their subsequent selenization using a rapid thermal annealing system

Journal of Solid State Electrochemistry - Band gap tuning of electrodeposited Cu(In1-x,Gax)Se2 thin films through varying In3+ and Ga3+ concentrations in the electrolytic bath is demonstrated....