A multifunctional nanohybrid based on mesoporous silica nanoparticle and biocompatible polypeptide was fabricated for targeted and dual-responsive therapy of tumor cells. 相似文献
Herein, two electrochemical methods based on potentiometric and impedimetric transductions were presented for albumin targeting, employing screen-printed platforms (SPEs) to make easy and cost-effective sensors with good detection merits. The SPEs incorporated ion-to-electron multi-walled carbon nanotubes (MWCNTs) transducer. Sensors were constructed using either tridodecyl methyl-ammonium chloride (TDMACl) (sensor I) or aliquate 336S (sensor II) in plasticized polymeric matrices of carboxylated poly (vinyl chloride) (PVC-COOH). Analytical performances of the sensors were evaluated using the above-mentioned electrochemical techniques. For potentiometric assay, constructed sensors responded to albumin with −81.7 ± 1.7 (r2 = 0.9986) and −146.2 ± 2.3 mV/decade (r2 = 0.9991) slopes over the linearity range 1.5 μM–1.5 mM with 0.8 and 1.0 μM detection limits for respective TDMAC- and aliquate-based sensors. Interference study showed apparent selectivity for both sensors. Impedimetric assays were performed at pH = 7.5 in 10 mM PBS buffer solution with a 0.02 M [Fe(CN)6]−3/−4 redox-active electrolyte. Sensors achieved detection limits of 4.3 × 10−8 and 1.8 × 10−7 M over the linear ranges of 5.2×10−8–1.0×10−4 M and 1.4×10−6–1.4×10−3 M, with 0.09 ± 0.004 and 0.168 ± 0.009 log Ω/decade slopes for sensors based on TDMAC and aliquate, respectively. These sensors are characterized with simple construction, high sensitivity and selectivity, fast response time, single-use, and cost-effectiveness. The methods were successfully applied to albumin assessment in different biological fluids. 相似文献
A key challenge in the design of magnetic molecular switches is to obtain bistability at room temperature. Here, we show that application of moderate pressure makes it possible to convert a paramagnetic FeIII2CoII2 square complex into a molecular switch exhibiting a full dia‐ to paramagnetic transition: FeIICoIII ? FeIIICoII. Moreover, the complex follows a rare behavior: the higher the pressure, the broader the magnetic hysteresis. Thus, the application of an adequate pressure allows inducing a magnetic bistability at room temperature with predictable hysteresis width. The structural studies at different pressures suggest that the pressure‐enhanced bistability is due to the strengthening of intermolecular interactions upon pressure increase. An original microscopic Ising‐like model including pressure effects is developed to simulate this unprecedented behavior. Overall, this study shows that FeCo complexes could be very sensitive piezo switches with potential use as sensors. 相似文献
The development of new techniques for rapid and continuous monitoring of urea in biomedical and clinical analysis is very important. Thus, conductive polymer-supported carbon nanotube as an effective electrochemical biosensing platform for direct detection of urea in blood samples was designed. For the assay optimization, several conductive polymers were synthesized and tested as electrode modifiers; among the tested polymers, poly-o-toluidine (PoT) showed the highest electrochemical signals. However, after the enzyme immobilization, direct bioelectrochemical signals were not obtained when the PoT was used alone. Due to the lower electrocatalytic feature of PoT, integration of carbon nanotube, to form a composite with the PoT, was exploited to enable the direct electron transfer. Successfully, using the hybrid, the catalytic activity of the immobilized urease enzyme was retained. Consequently, a sensitive and specific chronoamperometric signals were achieved after the bioassay optimization. Eventually, a standard calibration curve for urea determination was obtained. A linear range was found from 0.1 to 11 mM with the limit of detection of 0.03 mM. Successfully, several blood samples were analyzed and urea level was correlated with the reference analytical method.
Graphical abstract Scheme 1: Schematic representation of screen-printed electrode-modified urease biosensors. Three-layer functionalized surface (multi-walled carbon nanotube/poly(o-toluidine) nanocomposite, with glutaraldehyde (cross-linker and urease-immobilized enzyme), was designed for urea biosensors.
The relaxation of the metastable state of the spin-crossover compound [Fe(L)(2)](ClO(4))(2).H(2)O, with L = 2,6-bis(pyrazol-1-ylmethyl)pyridine, populated by the LIESST (light induced excited spin state trapping) effect, has been investigated by magnetic measurements. The time dependence of the relaxation curve at several temperatures, starting from different initial states, is in the shape of stretched exponentials, and the thermal variation of the photostationary state under constant photoexcitation is progressive and reversible. These features are satisfactorily modeled by considering noninteracting two-level systems with a distribution of activation energies. A suggested origin for the distribution is the conformational flexibility of the nonplanar heterocyclic ligands. The effect of the intensity distribution during the LIESST process is also accounted for in a simple way. 相似文献
ESI and CID mass spectra were obtained for two purine nucleoside antiviral agents (acycloguanosine and vidarabine) and one purine nucleotide (vidarabine monophosphate) and the corresponding compounds in which the labile hydrogens were replaced by deuterium gas phase exchange. The number of labile hydrogens, x, was determined from a comparison of ESI spectra obtained with N(2) and with ND(3) as the nebulizer gas. CID mass spectra were obtained for [M+H](+) and [M -H](-) ions and the exchanged analogs, [M(Dx)+D](+) and [M(Dx)-D](-), produced by ESI using a Sciex API-IIIplus mass spectrometer. Compositions of product ions and mechanisms of decomposition were determined by comparison of the CID mass spectra of the undeuterated and deuterated species. Protonated purine antiviral agents dissociate through rearrangement decompositions of base-protonated [M+H](+) ions by cleavage of the glycosidic bonds to give the protonated bases with a sugar moiety as the neutral fragment. Cleavage of the same bonds with charge retention on the sugar moiety gives low abundance ions, due to the low proton affinity of the sugar moiety compared to that of purine base. CID of protonated purine bases [B+H](+) occurs through two major pathways: (1) elimination of NH(3) (ND(3)) and (2) loss of NH(2)CN (ND(2)CN). Minor pathways include elimination of HNCO (DNCO), loss of CO, and loss of HCN (DCN). Deprotonated acycloguanosine and vidarabine exhibit the deprotonated base [B-H](-) as a major fragment from glycosidic bond cleavage and charge delocalization on the base. Deprotonated vidarabine monophosphate, however, shows predominantly phosphate related product ions. CID of deprotonated guanine shows two principal pathways: (1) elimination of NH(3) (ND(3)) and (2) loss of NH(2)CN (ND(2)CN). Minor pathways include elimination of HNCO (DNCO), loss of CO, and loss of HCN (DCN). The dissociation reactions of deprotonated adenine, however, proceed by elimination of HCN and (2) elimination of NCHNH (NCHND). The mass spectra of the antiviral agents studied in this paper may be useful in predicting reaction pathways in other heteroaromatic ring decompositions of nucleosides and nucleotides. 相似文献