Preparation of fluorescent sensor based on Zn metal-organic framework for detection and determination of raloxifene as an anticancer drug

Breast cancer is the second leading cause of death for women worldwide. Raloxifene (RLX) is a somewhat effective drug in lowering cholesterol, preventing and treating invasive breast cancer in postmenopausal women with osteoporosis, and does not interfere with breast tissue. Nevertheless, considering the possibility of risk in biological function due to excessive use of anticancer drugs and the adverse effects of drugs in wastewater on plants, animals, and aquatic, it is useful to determine the concentration of RLX in water and human body fluids. Here, a fluorescent metal-organic framework (MOF) nanoparticle based on trinuclear zinc clusters called Zn-MOF was presented, which is a high-performance and fast-response fluorescent chemosensor that can be used to detect RLX based on the fluorescence quenching medium in water. FTIR, XRD, SEM, and EDS analyses were used to identify the functional group and determine the structure and morphology of Zn-MOF. pH range 3-10. The prepared nanoparticles showed symmetric emission with excitation at a wavelength of 310.0 nm. The performance of the proposed fluorescent nanosensor was proportional to the quenching of the fluorescent signal with increasing RLX concentration at 404.0 nm; the quenching fluorescence response was linear in RLX concentration from 0.7 to 350 ng/mL with a significant detection limit equal to 0.485 nM.

Unraveling lignin degradation in fibre cement via multidimensional fluorometry

Pulp fibre reinforced cement (fibre cement) has the potential to become a forerunner in mitigating the carbon dioxide (CO2) footprint of non-structural materials for residential and commercial structures. However, one of the significant bottlenecks in fibre cement is its poor chemical stability in the alkaline cement matrix. To date, probing the health of pulp fibre in cement is lengthy and laborious, requiring mechanical and chemical separations. In this study, we have demonstrated that it is possible to understand the chemical interactions at the fibre-cement interfaces by tracking lignin in a solid state without using any additional chemicals. For the first time, multidimensional fluorometry is employed for the rapid assessment of the structural change (degradation) of lignin in fibre cement as an indicator of pulp fibre health; providing an excellent platform for the germination of resilient fibre cement with high content of natural lignocellulosic fibre.

Photochemistry in IUPAC: the Committee (1976–2001) and the Sub-Committee (2001–)

The history of the IUPAC Photochemistry Committee since its creation in 1976 and its transition in 2001 to the IUPAC Photochemistry Sub-Committee are reviewed as well as the connections of Committee and Sub-Committee to the various photochemical associations (European Photochemical Association, EPA, Inter-American Photochemical Society, I-APS and Asian and Oceanian Photochemistry Association, APA). The participants in both the Commission and the Sub-Committee over the years are listed as well as the Recommendations and Technical Reports produced since the creation of the Committee until the present days.

Utilizing inner filter effect in resonance Rayleigh scattering technique: a case study with silver nanocubes as RRS probe and several analytes as absorbers

It was demonstrated that the mechanism of the inner filter effect (IFE) can emerge well in the resonance Rayleigh scattering (RRS) technique and be utilized as a new analytical method in the design of innovative IFE-based sensors. To prove this process, silver nanocubes (Ag NCs) with tunable extinction spectra were selected as RRS probes, and three analytes, doxorubicin (DOX), sunitinib (SUN), and Alizarin Red S (ARS), were considered as the typical absorbers. In addition, in the presence of SUN as a typical analyte, the quenching of the RRS signal of Ag NCs, with λ_max of 419 nm, was linear in the range 0.01 to 2.5 µM of SUN. The limit of detection (LOD) was 0.0025 µM. The introduced method was then used to develop a dual-signal assay for the ratiometric determination of Al³⁺ ions. The suggested dual-signal assay was based on the color changes of ARS caused by Al³⁺ and the IFE between ARS and Ag NCs. The obtained results showed that the two characteristics of response sensitivity and linear dynamic range are very satisfactory for sensing Al³⁺ ions. The findings of this study demonstrate that the newly developed IFE mechanism can be employed as an attractive and highly efficient analytical technique for measuring different analytes.

Analyzing protein conjugation reactions for antibody-drug conjugate synthesis using polarized excitation emission matrix spectroscopy

Antibody-drug conjugates (ADCs) are promising anticancer therapeutics, which offer important advantages compared to more classical therapies. There are a variety of ADC critical quality attributes (CQAs) such as the protein structure, aggregation, and drug-to-antibody ratio (DAR), which all impact on potency, stability, and toxicity. Production processes can destabilize antibodies via a variety of physical and chemical stresses, and or by increased aggregation after conjugation of hydrophobic drugs. Thus, a proper control strategy for handling, production, and storage is necessary to maintain CQA levels, which requires the use of in-process quality measurements to first identify, then understand, and control the variables which adversely affect ADC CQAs during manufacturing. Here, we show how polarized excitation emission matrix (pEEM) spectroscopy, a sensitive, nondestructive, and potentially fast technique, can be used for rapidly assessing aggregation and DAR in a single measurement. pEEM provides several sources of information for protein analysis: Rayleigh scatter for identifying aggregate/particle formation and fluorescence emission to assess chemical and structural changes induced by attachment of a linker and/or a small molecule drug payload. Here, we used a nontoxic ADC mimic (monoclonal antibody with linker molecule) to demonstrate efficacy of the measurement method. Emission changes caused via light absorption by the attached linker, allowed us to predict DAR with good accuracy using fluorescence signal from the final purified products (6% relative error of prediction [REP]) and also from unpurified alkylation intermediates (11% REP). pEEM changes could also be correlated with size (hydrodynamic radius, R_h ) and aggregate content parameters obtained from dynamic light scattering and size exclusion chromatography (SEC). For the starting material and purified product samples, pEEM correlated better with R_h (R²  = 0.99, 6% REP) than SEC determined aggregate content (18% REP). Combining both fluorescence and light scatter signals also enabled in-process size quantification (6% REP). Overall, combining polarized measurements with EEM and Rayleigh scatter provides a single measurement, multi-attribute test method for ADC manufacturing.

Antioxidant assessment of agricultural produce using fluorescence techniques: a review

The study of bioactive compounds like food antioxidants is getting huge attention and curiosity by researchers and other relevant stakeholders (e.g., food and pharmaceutical industries) due to their health benefits. However, the currently available protocols to estimate the antioxidant activity of foods are time-consuming, destructive, require complex procedures for sample preparation, need technical persons, and not possible for real-time application, which are very important for large-scale or industrial applications. On the other hand, fluorescence spectroscopy and imaging techniques are relatively new, fast, mostly nondestructive, and possible to apply real-time to detect the antioxidants of foods. However, there is no review article on fluorescence techniques for estimating antioxidants in agricultural produces. Therefore, the present review comprehensively summarizes the overview of fluorescence phenomena, techniques (i.e., spectroscopy and computer vision), and their potential to monitor antioxidants in fruits and vegetables. Finally, opportunities and challenges of fluorescence techniques are described toward developing next-generation protocols for antioxidants measurement. Fluorescence techniques (both spectroscopy and imaging) are simpler and faster than available traditional methods of antioxidants measurement. Moreover, the fluorescence imaging technique has the potential to apply in real-time antioxidant identification in agricultural produce such as fruits and vegetables. Therefore, this technique might be used as a next-generation protocol for qualitative and quantitative antioxidants measurement after improvements like new material technologies for sensor (detector) and light sources for higher sensitivity and reduce the cost of implementing real-world applications.

Advanced Spectroscopy and APBS Modeling for Determination of the Role of His190 and Trp103 in Mouse Thymidylate Synthase Interaction with Selected dUMP Analogues

A homo-dimeric enzyme, thymidylate synthase (TS), has been a long-standing molecular target in chemotherapy. To further elucidate properties and interactions with ligands of wild-type mouse thymidylate synthase (mTS) and its two single mutants, H190A and W103G, spectroscopic and theoretical investigations have been employed. In these mutants, histidine at position 190 and tryptophan at position 103 are substituted with alanine and glycine, respectively. Several emission-based spectroscopy methods used in the paper demonstrate an especially important role for Trp 103 in TS ligands binding. In addition, the Advanced Poisson-Boltzmann Solver (APBS) results show considerable differences in the distribution of electrostatic potential around Trp 103, as compared to distributions observed for all remaining Trp residues in the mTS family of structures. Together, spectroscopic and APBS results reveal a possible interplay between Trp 103 and His190, which contributes to a reduction in enzymatic activity in the case of H190A mutation. Comparison of electrostatic potential for mTS complexes, and their mutants, with the substrate, dUMP, and inhibitors, FdUMP and N4-OH-dCMP, suggests its weaker influence on the enzyme-ligand interactions in N4OH-dCMP-mTS compared to dUMP-mTS and FdUMP-mTS complexes. This difference may be crucial for the explanation of the "abortive reaction" inhibitory mechanism of N4OH-dCMP towards TS. In addition, based on structural analyses and the H190A mutant capacity to form a denaturation-resistant complex with N4-OH-dCMP in the mTHF-dependent reaction, His190 is apparently responsible for a strong preference of the enzyme active center for the anti rotamer of the imino inhibitor form.

Development of a rapid polarized total synchronous fluorescence spectroscopy (pTSFS) method for protein quantification in a model bioreactor broth

Protein quantification during bioprocess monitoring is essential for biopharmaceutical manufacturing and is complicated by the complex chemical composition of the bioreactor broth. Here we present the early-stage development and optimization of a polarized total synchronous fluorescence spectroscopy (pTSFS) method for protein quantification in a hydrolysate-protein model (mimics clarified bioreactor broth samples) using a standard benchtop laboratory fluorometer. We used UV transmitting polarizers to provide wider range pTSFS spectra for screening of the four different TSFS spectra generated by the measurement: parallel (||), perpendicular (⊥), unpolarized (T) intensity spectra and anisotropy maps. TSFS_|| (parallel polarized) measurements were the best for protein quantification compared to standard unpolarized measurements and the Bradford assay. This was because TSFS_|| spectra had a better analyte signal to noise ratio (SNR), due to the anisotropy of protein emission. This meant that protein signals were better resolved from the background emission of small molecule fluorophores in the cell culture media. SNR of >5000 was achieved for concentrations of bovine serum albumin/yeastolate 1.2/10 g L^-1 with TSFS_|| . Optimization using genetic algorithm and interval partial least squares based variable selection enabled reduction of spectral resolution and number of excitation wavelengths required without degrading performance. This enables fast (<3.5 min) online/at-line measurements, and the method had an LOD of 0.18 g L^-1 and high accuracy with a predictive error of <9%.