We demonstrated citrate-capped gold nanoparticles assisted characterization of amine functionalized polystyrene plate and glass slide surfaces through AuNPs staining method. The effect of AuNPs concentration on the characterization of amine modified surfaces was also studied with different concentration of AuNPs (ratios 1.0–0.0). 3-Aminopropylyl triethoxy silane has been used as amine group source for the surface modification. The interactions of AuNPs on modified and unmodified surfaces were investigated using atomic force microscopy and the dispersibility, and the aggregation of AuNPs was analyzed using UV–visible spectrophotometer. Water contact angle measurement and X-ray photoelectron spectroscopy (XPS) were used to further confirmation of amine modified surfaces. The aggregation of AuNPs in modified multiwell plate leads to the color change from red to purple and they are found to be adsorped on the modified surfaces. Aggregation and adsorption of AuNPs on the modified surfaces through the electrostatic interactions and the hydrogen bonds were revealed by XPS analysis. Remarkable results were found even in the very low concentration of AuNPs (ratio 0.2). This AuNPs staining method is simple, cost-effective, less time consuming, and required very low concentration of AuNPs. These results can be read out through the naked eye without the help of sophisticated equipments.

Background/Objectives: Phloroglucinol (PHL), a phenolic compound extracted from the brown alga Rosenvingea intricata, exhibits potent antioxidant and anticancer properties. This study aims to extract, purify, and characterize PHL, and further develop functionalized zinc oxide nanoparticles (ZnO NPs) loaded with PHL to enhance its therapeutic potential. Methods: PHL was extracted using acetone and purified through Sephadex LH-20 column chromatography, yielding a highly enriched fraction (F-3). The purified compound was characterized by FTIR, HPLC, NMR, and LC-MS. ZnO NPs were synthesized, PEGylated, and conjugated with PHL, forming ZnO-PEG-PHL NPs. Their characterization included DLS, zeta potential, XRD, SEM-EDAX, and encapsulation efficiency studies. Antioxidant assays (DPPH, FRAP, ABTS, RPA) were performed and in vitro cytotoxicity on A549 lung cancer cells were determined to evaluate the therapeutic efficacy of PHL. Results: The purified PHL fraction showed a high phenolic content (45.65 PHL mg/g), which was was confirmed by spectral analysis. The ZnO-PEG-PHL NPs increased in size from 32.36 nm to 46.68 nm, with their zeta potential shifting from −37.87 mV to −26.82 mV. The antioxidant activity was superior for the ZnO-PEG-PHL NPs in all assays, while the in vitro cytotoxicity tests showed an IC₅₀ of 40 µg/mL compared to 60 µg/mL for the ZnO NPs and 70 µg/mL for PHL. Apoptotic studies revealed significant cell cycle arrest and apoptosis induction. Conclusions: The synthesized ZnO-PEG-PHL NPs demonstrated enhanced antioxidant and anticancer properties, making them promising candidates for cancer therapy and antioxidant applications.

In the original publication of the article, the subheadings of Table 1 were incorrectly published. The correct version of Table 1 is given below.