The Three-region Method of Color Matching in the Presence of Fluorescent Whitening Agents

An expression of reflectance of fluorescent dyes in emission region was used in this article. Through the analysis of the spectral radiance factor of fluorescent whitening agents(FWA), the color matching of FWA was studied and the three-region method of color matching method was put forward. The method was proved to be reliable for the dyes used and was easy to apply for the color matching of FWAs.

Spectrofluorometric Study of the Inclusion Complexation of Fluorescent Whitening Agents and β-Cyclodextrins

The inclusion complexation behavior of 2,5-Bis(5-tert-butyl-benzoxazol-2yl)-thiophene (UVOB) with native β-cyclodextrin (βCD) and βCD-monochlorotriazinyl (βCD-MCT) was evaluated by fluorescence spectroscopy. The association constant (Ks), stoichiometry, , and were evaluated at 25℃ ± 0.1℃ in phosphate buffer solution (pH = 10.5, 0.1 mo•dm–3) in order to find out the complex formation ability and stability. Fluorescence enhancement for UVOB and UVBNB with both CDs has been observed as a result of the complex formation. A stoichiometry 1:1 for UVOB in both CDs was observed;a stoichiometry 3:1 for UVBNB in both CDs has been observed. The Ksvalues for UVOB were 4916 ± 137 M–1 and 655 ± 19 M–1 (acetone: water 90/10, v/v) with βCD and βCD-MCT, respectively. The value obtained indicates a spontaneous and stable complex formation, but the complex βCD-UVOB showed high Ks value as an indicative of a high concentration of complex formed. Additionally, Ks and thermodynamic parameters and were evaluated in a commercial product UVBNB (UVOB, 13%, v/v). In aqueous solution, the values obtained were 2552 ± 115 and 1787 ± 75 M–1 respectively. Complexation of UVOB with CDs is an interesting approach for utilization of UVOB in aqueous systems without the need of solvents and or surfactants used in commercial product (UVBNB).

Perylene-Based Fluorescent Sizing Agent for Precise Evaluation of Permeability and Coating Property of Sizing Paste

Warp sizing is considered as the most important process of weaving preparation in the textile field.The quality of sized warp yarns is directly determined by the permeation and coating of sizing paste into/on warp yarns.However,many significant flaws of the current method of permeability and coating property of sizing paste,such as low accuracy and narrow variety adaptability for sizing agents and warp yarns,have emerged in the evaluation process.In order to eliminate the inherent flaws in the current method,the investigation chose chitosan(CS)as a representative of common sizing agents,introduced various amounts of perylene units onto molecular chains of the CS,and prepared a new functional sizing agent-fluorescent CS with different labeling degrees of perylene.Furthermore,PVA-perylene was synthesized to evaluate the permeability and coating property of PVA sizing paste.Then,three indexes to indicate the permeability and coating property of sizing paste,i.e.permeation percentage,coating percentage and integrity percentage of sizing film,were evaluated using the CS-perylene and PVA-perylene derivatives prepared.Due to the fluorescence emitted by the perylene units,the three indexes can be determined accurately and conveniently depending on only fluorescent microscope and common image processing software.The investigation efficiently solves the difficult problem of evaluating permeation and coating property of the pastes of both bio-based and petroleum-based sizing agents with appropriate degrees of labeling and has a significant guiding function on accurate determination of the quality of sized yarns.

Direct Determination of Migration Amount of Fluorescent Whitening Agents in Facial Mask

Facial mask is a kind of skin care cosmetics, in which fluorescent whitening agents（FWAs） were added to make face skin look whiter and brighter. In this work, pig skin was used instead of human skin to test the methods. Three methods, including pig skin migration fluorescent spectrophotometry（FS）, fiber paper migration FS, and fiber paper migration visual colourimetry（VC）, were developed for determining the migration amount of FWAs from facial mask to pig skin. In the methods, a self-assembly light source and fluorescence collecting unit was used. The unit can be easily moved and the measurement was very convenient. Some experimental conditions were optimized. The fiber paper migration VC can give semi-quantitative results and was the simplest one in the three methods because collec- tion, separation and detection of the fluorescence were not needed. Both the pig skin migration FS and fiber paper migration FS can give quantitative results and compared with fiber paper migration FS, the pig skin migration FS could give more practical results by simulating the real way of using facial mask. The limits of detection for disodium 4,4＇-bis[（4-anilino-6-hydroxyethylamion-1,3,5-triazin-2-yl）amion]stilbene-2,2＇-disulphonate（VBL） obtained by pig skin migration FS and fiber paper migration FS were 0.03 and 0.05 mg/m2, respectively. 96 kinds of samples were analyzed and the migration amounts of FWAs in 21 kinds of samples were detectable. Correlations between migration amounts obtained by the three methods were very good. Experimental results indicate that the present methods can be applied to the determination of migration amount of FWAs in facial masks.

A Plasma Membrane Polarity Sensor Harnessing Conjoined Twisted Intramolecular Charge Transfer Modulation and Charge Number Control Strategy

Polarity is a critical microenvironmental factor of the plasma membrane,which can offer valuable insights into various biological processes.Herein,we proposed a novel strategy for the construction of fluorescent agents to measure plasma membrane polarity by conjoining twisted intramolecular charge transfer(TICT)modulation and charge number control.It is shown that compounds with a stronger TICT tendency are more sensitive to polarity shifts due to the number of dialkylated amino groups present(from 1 to 3),and the molecules with two or more charged centers remain in the plasma membrane.Therefore,we developed two fluorescent agents with high polarity sensitivity,excellent turn-on ratios,and superior ability,to target the plasma membrane.In the wash-free fluorescence imaging and fluorescence lifetime tests,our designed agent could detect plasma membrane polarity with high precision,allowing effective distinction between cancer cells and normal cells based on their differences in plasma membrane polarity.Moreover,both fluorescence and fluorescence lifetime changes of the plasma membrane in the ferroptosis model established by Sorafenib confirmed an increase in plasma membrane polarity during cell ferroptosis.

Ovalbumin-stabilized gold nanoclusters with ascorbic acid as reducing agent for detection of serum copper

Ovalbumin-stabilized gold nanoclusters （OVA@AuNCs） were prepared with ascorbic acid as a reducing agent. This strategy could realize the synthesis of water-soluble OVA@AuNCs within 20 min. The asprepared fluorescent probe showed a red fluorescence emission at 630 nm. Moreover, the properties of the OVA@AuNCs were characterized by transmission electron microscope, dynamic light scattering, ultraviolet-visible spectroscopy, fluorescent spectroscopy. Based on the surface electron density decrease-induced fluorescence quenching mechanism, the OVA@AuNCs provided high sensitivity and selectivity for sensing copper ions. A good linear relationship was obtained between the fluorescence intensity of OVA@AuNCs and the concentration of copper ions in the range of 5.0-100.0pumol/L （R2z0.999） with a detection limit of 640 nmol/L. Furthermore, the rat serum copper contents were determined by using the OVA@AuNCs based assay, indicating great potential of fluorescent probes for application in biological and clinical analysis.

Polymeric dual-modal imaging nanoprobe with two-photon aggregation-induced emission for fluorescence imaging and gadolinium-chelation for magnetic resonance imaging

Nanoprobes that offer both fluorescence imaging(FI)and magnetic resonance imaging(MRI)can provide supplementary information and hold synergistic advantages.However,synthesis of such dual-modality imaging probes that simultaneously exhibit tunability of functional groups,high stability,great biocompatibility and desired dual-modality imaging results remains challenging.In this study,we used an amphiphilic block polymer from(ethylene glycol)methyl ether methacrylate(OEGMA)and N-(2-hydroxypropyl)methacrylamide(HPMA)derivatives as a carrier to conjugate a MR contrast agent,Gd-DOTA,and a two-photon fluorophore with an aggregation-induced emission(AIE)effect,TPBP,to construct a MR/two-photon fluorescence dual-modality contrast agent,Gd-DOTA-TPBP.Incorporation of gadolinium in the hydrophilic chain segment of the OEGMA-based carrier resulted in a high r_(1)value for Gd-DOTA-TPBP,revealing a great MR imaging resolution.The contrast agent specifically accumulated in the tumor region,allowing a long enhancement duration for vascular and tumor contrast-enhanced MR imaging.Meanwhile,coupling TPBP with AIE properties to the hydrophobic chain segment of the carrier not only improved its water solubility and reduced its cytotoxicity,but also significantly enhanced its imaging performance in an aqueous phase.Gd-DOTA-TPBP was also demonstrated to act as an excellent fluorescence probe for two-photon-excited bioimaging with higher resolution and greater sensitivity than MRI.Since high-resolution,complementary MRI/FI dual-modal images were acquired at both cellular and tissue levels in tumor-bearing mice after application of Gd-DOTA-TPBP,it has great potential in the early phase of disease diagnosis.