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Rapid qualitative and quantitative analysis of 4-methylimidazole (4-MEI) in caramel and beverage samples is demonstrated using the paper spray form of ambient ionization mass spectrometry. The minimum level of pure 4-MEI detectable using multiple reaction monitoring (MRM) in a triple quadrupole instrument was 3 pg μL⁻¹ in neat solvent and 5 pg μL⁻¹ in a matrix containing caramel. This method was used to analyze 11 caramel samples for 4-MEI. After implementing effective quality control protocols, average relative standard deviations for paper spray triple quadrupole MS were less than 15% and the linear dynamic range was three orders of magnitude. Results obtained on three different days by two different analyst groups agreed closely. An ion trap tandem MS method of approximate quantitative analysis is also described and it gave similar precision to the triple quadrupole experiment when fluctuations in ion currents were cancelled by simultaneously isolating the analyte and internal standard and fragmenting both in an ion trap simultaneous MRM experiment. As another alternative, a rapid qualitative screening method based on the use of high-resolution measurements instead of tandem mass spectrometry using an Orbitrap was also tested and found to give a detection limit of 100 pg μL⁻¹.

In this paper, a rigid scaffold imposes the photophysics of chromophores with a benzylidene imidazolidinone core by mimicking the β-barrel structure of the green fluorescent protein (GFP) and its analogs. The designed artificial frameworks maintain fluorescence responses and, therefore, conformational rigidity of typically non-emissive GFP-related chromophores. To replicate a small weight percent of the chromophore inside the natural GFP, two synthetic approaches were utilized: coordinative immobilization and non-coordinative inclusion. Despite low chromophore loading in the rigid matrix, both approaches resulted in formation of photoluminescent hybrid materials. Furthermore, the rigid scaffold dictates chromophore fluorescence by replicating its behavior in solution or the solid state. The presented results open an avenue for utilization of rigid scaffolds in the engineering of materials with tunable photoluminescence profiles for a variety of practical applications.

The synthesis and anti-cancer activity evaluation of fused imidazoquinoline compounds is reported in this paper. Yb(OTf)3 has been utilized as a catalyst for the synthesis of 1,4-diaryl substituted imidazo[4,5-c]quinolines via a modified Pictet-Spengler approach. The desired imidazole ring was synthesized from imines using TosMIC (toluenesulfonylmethyl isocyanide) and subsequently functionalized at the C-4 position yielding an imidazoquinoline skeleton. Importantly, the final step was carried out without the aid of any prefunctionalization to obtain the resultant compounds in good yields. The synthesized compounds, when screened for anti-cancer activity, revealed the highest activity with 4-(2-bromophenyl)-1-phenyl-1H-imidazo[4,5-c]quinoline (IC50: 103.3 μM).

In this paper, a kind of aminopropyl imidazole-modified silica sorbent was synthesized and used as a solid-phase extraction (SPE) sorbent for the determination of carboxylic acid compounds and polycyclic aromatic hydrocarbons (PAHs). The resultant aminopropyl imidazole-modified silica sorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA) to ensure the successful binding of aminopropyl imidazole on the surface of silica gel. Then the aminopropyl imidazole-modified silica sorbent served as a SPE sorbent for the enrichment of carboxylic acid compounds and PAHs. The new sorbent exhibited high extraction efficiency towards the tested compounds and the results show that such a sorbent can offer multiple intermolecular interactions: electrostatic, π-π, and hydrophobic interactions. Several parameters affecting the extraction recovery, such as the pH of sample solution, the pH of eluent, the solubility of eluent, the volume of eluent, and sample loading, were also investigated. Under the optimized conditions, the proposed method was applied to the analysis of four carboxylic acid compounds and four PAHs in environmental water samples. Good linearities were obtained for all the tested compounds with R(2) larger than 0.9903. The limits of detection were found to be in the range of 0.0065-0.5 μg L(-1). The recovery values of spiked river water samples were from 63.2% to 112.3% with relative standard deviations (RSDs) less than 10.1% (n = 4).

This paper reports for the first time in situ crystal growth of ZIF-8 on electrospun polyurethane (PU) nanofibers. In SEM images, continuous and compact ZIF-8 nanocrystals grow along electrospun PU nanofibers. The highest loading capacity of ZIF-8 on PU reaches 63%. By N2 adsorption-desorption, ZIF-8-PU shows a high surface area of 566 cm(2) g(-1). Combining the good flexibility of PU with the high adsorption properties of ZIF-8, ZIF-8-PU can be easily tailored into clothes or other forms as adsorption material. Furthermore, the gas adsorption ability of ZIF-8-PU was measured for H2, N2, O2 and CO2 at room temperature (20 °C) under different pressure gradients. The results show that the adsorption capacity of ZIF-8-PU for CO2 is nearly 11 times that for H2, 50 times that for O2 and 75 times that for N2 at 800 mmHg.

This paper describes a convenient approach to quantitative removal of the synthetic host cucurbit[8]uril (Q8) from aqueous mixtures using a sepharose resin coated in memantine groups to selectively sequester Q8 in the presence of competing hosts and guests. The "Q8 sponge" can separate Q8 from Q6 and reverse the Q8-mediated dimerization of peptides.

Naphthoimidazolium groups can form unique ionic hydrogen bonds with anions as imidazolium moieties, and in addition, they are fluorescent, so no further elaborative synthesis is needed to introduce a fluorescent group. In this paper, three naphthoimidazolium derivatives were synthesized and studied for the recognition of nucleotides. Compound 1 composed of a single naphthoimidazolium group and quaternary ammonium group did not show any significant fluorescent changes with various anions and nucleotides, such as ATP, GTP, CTP, TTP, UTP, ADP and AMP. A tripodal compound 3 bearing three naphthoimidazolium groups and three quaternary ammonium groups, respectively, showed large fluorescence enhancements with UTP, CTP and TTP and moderate fluorescence enhancements with ATP and pyrophosphate and a fluorescence quenching effect with GTP. On the other hand, compound 2 bearing two naphthoimidazolium groups and two quaternary ammonium groups displayed a selective fluorescence enhancement with ATP and a selective fluorescence quenching effect with GTP in 100% aqueous solution.

This paper presents a pH-sensitive bifunctional crosslinker that enables facile conjugation of small molecule therapeutics to macromolecular carriers for use in drug delivery systems. This N-ethoxybenzylimidazole (NEBI) bifunctional crosslinker was designed to exploit mildly acidic, subcellular environments to trigger the release of therapeutics upon internalization in cells. We demonstrate that an analog of doxorubicin (a representative example of an anticancer therapeutic) conjugated to human serum albumin (HSA, a representative example of a macromolecular carrier) via this NEBI crosslinker can internalize and localize into acidic lysosomes of ovarian cancer cells. Fluorescence imaging and cell viability studies demonstrate that the HSA-NEBI-doxorubicin conjugate exhibited improved uptake and cytotoxic activity compared to the unconjugated doxorubicin analog. The pH-sensitive NEBI group was also shown to be relatively stable to biologically-relevant metal Lewis acids and to serum proteins, supporting that these bifunctional crosslinkers may be useful for constructing drug delivery systems that will be stable in biological fluids such as blood.

In this paper, we described the electrogenerated chemiluminescence (ECL) processes of tris(2,2'-bipyridine) ruthenium(II) (Ru(bpy)(3)(2+)) in room-temperature ionic liquid (RTIL). The results showed that ECL signals in RTIL, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF(4)), were stronger than those obtained in aqueous solutions, which means that the RTIL could be used as a good solvent for ECL. The effect of tri-n-propylamine (TPrA) on the ECL process in [Bmim]BF(4) was also investigated and the results showed that the ECL peak occurred at 1.9 V, which is more positive than the previous reports in aqueous solutions, and the ECL intensity reached the maximum when the scan rate of CV is 200 mV s(-1). Moreover, the ECL signal can be quenched by oxygen due to the reaction of oxygen with TPrA* and Ru(bpy)(3)(+). Finally, the inhibition of Ru(bpy)(3)(2+) ECL by water-insoluble analyte, naphthol, was carried out and the results showed that the ECL signal can be quenched completely by naphthol at a very low concentration (1.0 x 10(-6) M).