Simple method to determine the concentration and incorporation ratio of ruthenium-labeled antibodies

Aim: Ruthenium-labeled antibodies are commonly used detection reagents in bioanalysis assays and must be characterized to ensure quality. The aim of this work was to develop a method to determine the concentration and incorporation ratio (the degree of labeling [DOL]) of ruthenium-labeled antibodies by UV/VIS spectroscopy. Materials & methods: Free SULFO-TAG compound was scanned using UV/VIS and showed an absorbance peak at 292 nm. In contrast, antibodies demonstrate UV absorbance at 280 nm. After experimentally determining the extinction coefficients at 280 and 292 nm of free ruthenium and antibody, we generated a formula based on the Beer–Lambert law that calculates both concentration and DOL of these ruthenium-labeled antibodies. Conclusion: The concentration and DOL values determined by our method were comparable to those determined from bicinchoninic acid and LC/MS for the same reagents. This method creates a faster and more accessible reagent characterization process that uses far less reagent than the more traditional alternatives.

Active Double-Layered Films Enriched with AgNPs in Great Water Dock Root and Pu-Erh Extracts

A novel, eco-friendly, and biocompatible method was applied to form silver nanoparticles (AgNPs) in great water dock (Lapathi radix) (KB) and pu-erh (Camellia sinensis) (PE) extracts. The surface plasma resonance peak of green synthesized AgNPs at 451.8 nm for AgNPs+KB and 440.8 nm for AgNPs+PE was observed via spectral analysis of UV absorbance. In this study, double-layered biopolymer films (FUR/CHIT+HGEL) with AgNPs incorporated in KB solution (AgNPs+KB) and AgNPs in PE solution (AgNPs+PE), were successfully prepared using the casting method. The SEM, XRD, zeta potential and size analyses confirmed the presence of AgNP in the films. The addition of AgNPs in plant extracts improved antimicrobial and antioxidant activity and thermal stability, whereas WVTR experienced a decrease. The nanocomposite films’ orange-brown colour may aid in the protection of food products against UV rays. The composite films demonstrated antibacterial activity against food-borne pathogens and may offer potential in food packaging applications.

Can Spectrophotometry Be Used to Quantify Zingiberene Sesquiterpenoids in Tomato Leaflet Extracts?

The presence of 7-epi zingiberene in wild tomatoes has been associated with arthropod resistance. Consequently, tomato breeders are attempting to introgress 7-epi zingiberene from wild to cultivated tomato requiring quantification of zingiberene. 7-Epi zingiberene likely absorbs UV light due to its conjugated double bonds and others have claimed that measurement of absorbance at 270 nm of tomato leaflet washes can be used to quantify zingiberene. However, this claim has never been critically evaluated. We initially evaluated this claim in an interspecific hybrid tomato generation that was segregating widely for zingiberene. Results indicated that the method does not obey the Beer–Lambert law. Consequently, we examined in detail aspects of the UV-absorbance of isolated zingiberenoids and leaflet washes obtained from parents and interspecific generations that were segregating for 7-epi zingiberene. Results indicated that isolated zingiberenoids, as well as leaflet washes containing zingiberenoids, have broad absorbance spectra with a λmax of 264 nm. For isolated zingiberenoids, the relationship between abundance and absorbance at 264 nm did obey the Beer–Lambert law. Average absorbance spectra for leaflet washes from interspecific generation plants showed subtle λmax shifts. Furthermore, the relationship between absorbance at 264 nm and zingiberenoid content of these generations did not obey the Beer–Lambert law. The use of multiple wavelengths for estimation of zingiberenoids in these breeding generations was explored and the inclusion of additional absorbances at one or two wavelengths always improved estimates. However, identified wavelength(s) differed among generations. Taken together, the results indicate that measurement of absorbance of tomato leaflet washes at a single wavelength is not a reliable quantitative estimate of zingiberenoids in leaflet washes. Estimates can be improved by utilizing absorbance at multiple wavelengths, but the particular wavelengths will vary among generations. Lastly, measurement of absorbance may be useful for identifying those relatively rare individuals in a generation that is widely segregating for zingiberenoid content. However, even in this situation, the determination of the actual 7-epi zingiberene content would need to be backstopped by a valid quantitative method.

Zinc oxide-induced changes to sunscreen ingredient efficacy and toxicity under UV irradiation

Sunscreen safety and efficacy is generally evaluated based upon the properties of the individual chemicals in a formulation. However, the photostability of sunscreens has been shown to be highly dependent on the mixture of chemicals present. To better understand how sunscreen formulation influences stability, and to establish a foundation for probing the influence of zinc oxide additives, we formulated five different small-molecule based ultraviolet-filter (UV-filter) mixtures with a Sun Protection Factor (SPF) of 15. These mixtures contained active ingredients approved in either the United States or European Union and were designed to represent formulations of actual products on the market. We evaluated the photostability and toxicity of these mixtures in the absence and presence of zinc oxide after UV exposure for two hours. Changes in UV absorbance were minimal for all five small-molecule-based mixtures without zinc oxide. The presence of either micro- or nano-sized zinc oxide caused significant small-molecule photodegradation and the degraded mixtures exhibited higher levels of toxicity in embryonic zebrafish assays. This study suggests that caution must be taken when formulating sunscreens containing both zinc oxide and small-molecule UV-filters to avoid unintended consequences during use. Graphic abstract

Preparation of chitosan-glucosamine derivatives (Maillard reaction products) by gamma Co-60 irradiation method and investigation of antibacterial activity

The mixture solutions of glucosamine and chitosan with different molecular weights(123.5; 40.7 and 6.1 kDa) were irradiated by Co-60 gamma ray at dose of 50 kGy to prepare chitosanglucosamine Maillard reaction products (MRPs). The formation of MRPs was determined by measuring UV absorbance (at 284) nm and browning (at 420 nm). The reaction efficiency was calculated based on the ratio of reacted glucosamine and total added glucosamine. The antibacterial activity of chitosan-glucosamine MRPs against Escherichia coli was also investigated. The obtained results showed that the chitosan-glucosamine MRPs exhibited strong antibacterial activity, in which chitosan-glucosamine MRPs prepared from 123.5 kDa chitosan could reduce up to 4 log CFU/ml in comparison with the control (45 × 106 CFU/ml). Therefore, the chitosan-glucosamine MRPs prepared by the Co-60 gamma irradiation method can be potentially applied as a natural preservative for food, cosmetics and substituted for banned chemical preservatives.

Water Treatment in Hybrid Connection of Coagulation, Ozonation, UV Irradiation and Adsorption Processes

In recent years, conventional water treatment systems have been supported by ozonation or UV irradiation processes. The efficiency of four hybrid processes: (1) coagulation and adsorption, (2) ozonation and coagulation, (3) ozonation, coagulation and adsorption, (4) ozonation, UV irradiation, coagulation and adsorption of inorganic and organic pollutants removal was analysed. In the presented study, the content of organic matter in natural water was evaluated as colour, oxidisability (OXI), total and dissolved organic carbon (TOC and DOC) content and UV absorbance at the wavelength of 254 nm for natural and modified water. Additionally, removal of Ni2+, Cd2+and Pb2+ ions during the treatment processes was analysed. The coagulation process with the use of polyaluminium chloride removed 45% of colour and 39, 26% and 45% of OXI, TOC and UV absorbance, respectively. Using the ozonation before coagulation increased efficiency of colour and UV254 absorbance reduction by 33% and 25%, respectively. Coagulation with both UV irradiation and adsorption had insignificant results on the analysed factors value. The coagulation process was the most efficient for metal ions removal (40–78%). The ozonation process before coagulation increased removal up to 55–85%. Additional irradiation with UV or using of the adsorbent during coagulation of initially ozonated water had an insignificant impact on metal ions concentration in water.