Distinct morphological MgO nanoparticles (MgONPs) were synthesized using biomasses of Saussurea costus roots. The biomass of two varieties of Saussurea costus (Qustal hindi and Qustal bahri) were used in the green synthesis of MgONPs. The physical and chemical features of nanoparticles were confirmed by spectroscopic and microscopic techniques. The surface morphology of the obtained nanoparticles was detected at different magnifications by SEM and TEM microscopy and the size of nanoparticles were found to be 30 and 34 nm for Qustal hindi and Qustal bahri, respectively. The antimicrobial activity of the prepared MgONPs was screened against six pathogenic strains. The synthesized nanoparticles by Qustal bahri biomass exerted significant inhibition zones 15, 16, 18, 17, 14, and 10 mm against E. coli, P. aeruginosa, C. tropicalis and C. glabrata, S. aureus and B. subtilis as compared to those from Qustal hindi 12, 8 and 17 mm against B. subtilis, E. coli and C. tropicalis, respectively. MgONPs showed a potential cytotoxicity effect against MCF-7 breast cancer cell lines. Cellular investigations of MgONPs revealed that the prepared nanoparticles by Qustal bahri exhibited high cytotoxicity against MCF-7 cancer cell lines. IC 50 values in MCF-7 cells were found to be 67.3% and 52.1% for MgONPs of Saussurea costus biomasses, respectively. Also, the photocatalytic activity of MgONPs of each Saussurea costus variety was comparatively studied. They exhibited an enhanced photocatalytic degradation of methylene blue after UV irradiation for 1 h as 92% and 59% for those prepared by Qustal bahri and Qustal hindi, respectively. Outcome of results revealed that the biosynthesized MgONPs showed promising biomedical potentials.

The clinical detection of carbohydrate antigen 19-9 (CA 19-9), a tumor marker in biological samples, improves and facilitates the rapid screening and diagnosis of pancreatic cancer. A simple, low cost, fast, and green synthesis method to prepare a viable carbon quantum dots/gold (CQDs/Au) nanocomposite fluorescence immunosensing solution for the detection of CA 19-9 was reported. The present method is conducted by preparing glucose-derived CQDs using a microwave-assisted method. CQDs were employed as reducing and stabilizing agents for the preparation of a CQDs/Au nanocomposite. The immobilized anti-CA 19-9-labeled horseradish peroxidase enzyme (Ab–HRP) was anchored to the surface of a CQDs/Au nanocomposite by a peptide interaction between the carboxylic and amine active groups. The CA 19-9 antigen was trapped by another monoclonal antibody that was coated on the surface of microtiter wells. The formed sandwich capping antibody–antigen–antibody enzyme complex had tunable fluorescence properties that were detected under excitation and emission wavelengths of 420 and 530 nm. The increase in fluorescence intensities of the immunoassay sensing solution was proportional to the CA 19-9 antigen concentration in the linear range of 0.01–350 U mL−1 and had a lower detection limit of 0.007 U mL−1. The proposed CQDs/Au nanocomposite immunoassay method provides a promising tool for detecting CA 19-9 in human serum.

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