Catalytically active individual gold (Au) and cerium oxide (CeO) nanoparticles (NPs) are well known to exhibit specific enzyme-like activities, such as natural catalase, oxidase, superoxide dismutase, and peroxidase enzymes. These activities have been maneuvered to design several biological applications such as immunoassays, glucose detection, radiation and free radical protection and tissue engineering. In biological systems, multienzyme complexes are involved in catalyzing important reactions of essential metabolic processes such as respiration, biomolecule synthesis, and photosynthesis. It is well known that metabolic processes linked with multienzyme complexes offer several advantages over reactions catalyzed by individual enzymes. A functional nanozyme depicting multienzyme like properties has eluded the researchers in the nanoscience community for the past few decades. In the current report, we have designed a functional multienzyme in the form of Gold (core)-CeO (shell) nanoparticles (Au/CeO CSNPs) exhibiting excellent peroxidase, catalase, and superoxide dismutase enzyme-like activities that are controlled simply by tuning the pH. The reaction kinetic parameters reveal that the peroxidase-like activity of this core-shell nanozyme is comparable to natural horseradish peroxidase (HRP) enzyme. Unlike peroxidase-like activity exhibited by other nanomaterials, Au/CeO CSNPs showed a decrease in hydroxyl radical formation, suggesting that the biocatalytic reactions are performed by efficient electron transfers. A significant enzyme-like activity of this core-shell nanoparticle was conserved at extreme pH (2-11) and temperatures (up to 90 °C), clearly suggesting the superiority over natural enzymes. Further, the utility of peroxidase-like activity of this core-shell nanoparticles was extended for the detection of glucose, which showed a linear range of detection between (100 µM to 1 mM). It is hypothesized that the proximity of the redox potentials of Au/Au and Ce (III)/Ce (IV) may result in a redox couple promoting the multienzyme activity of core-shell nanoparticles. Au/CeO CSNPs may open new directions for development of single platform sensors in multiple biosensing applications.

In this study, a serotonin−stearic acid (ST-SA)-based bioconjugate was synthesized for the surface modification of manganese oxide-based nanocuboids (MNCs) for delivering of anticancer drug (i.e., doxorubicin hydrochloride (DOX)) to human liver cancer cells. MNCs were synthesized by chemical precipitation method, and their surface was modified with ST-SA bioconjugate for targeting of MNCs to cancer cells. The ST-SA@MNCs along with DOX showed good colloidal stability, high drug encapsulation (98.3%), and drug loading efficiencies (22.9%) as well as pH-responsive biodegradation. Coating with ST-SA conjugate provided a shield to MNCs which sustained their degradation in an acidic environment. The release of DOX was higher (81.4%) in acidic media than under the physiological conditions (20.5%) up to 192 h. The in vitro antiproliferation assay showed that ST-SA@MNCs exhibit higher cell growth inhibition compared to that of pure DOX after 48 h of treatment. The cellular uptake and apoptosis studies revealed the enhanced uptake of ST-SA@MNCs in contrast to the MNCs due to overexpressed ST receptor on hepatocellular carcinoma cells and triggered the generation of reactive oxygen species in the cells. Therefore, these results indicated that the DOX-loaded, ST-SA stabilized MNCs improved the therapeutic index of DOX and would be a promising therapeutic candidate for tumor therapy.

Globally, prostate cancer is the fifth major cancer type and the second leading cause of cancer-related death in men. In 2018, about 1.3 million prostate cancer cases were reported worldwide. It is reported that loss of PTEN (tumor suppressor gene) expression leads to hyperactivation of the PI3K/AKT pathway and thus induces uncontrolled cell proliferation. Loss or mutation in regular PTEN expression is reported to occur in ∼30% of primary prostate cancer cases and ∼65% of metastatic cancer cases. Restoring the PTEN expression could inhibit the PI3K/AKT/mTOR signaling pathway, thus avoid the growth of prostate cancer cells. In this work, we have synthesized a multifunctional nanoliposomal formulation incorporating PTEN plasmid, AKT3 siRNA, and antioxidant cerium oxide nanoparticles (CeNPs). The nanoliposomes were able to successfully internalize in prostate cancer (PC-3) cells, restore the expression of PTEN protein, and knock down AKT3 mRNA. Further, the multifunctional nanoliposomes induce DNA damage and apoptosis in prostate cancer cells. The investigation of the PI3K/AKT/mTOR signaling pathway revealed that PTEN protein and apoptosis-specific proteins are overexpressed, leading to the inhibition of oncoproteins and, thus, prostate cancer.

Prostate cancer is the second leading cause of cancer death in men and about one in nine will be diagnosed in his lifetime. Loss of PTEN has been considered as one of the major factors leading to the origin of prostate cancer through modulating PI3K/AKT signaling pathways. In this study, we have prepared a multifunctional antioxidant nanoliposome containing PTEN plasmid and cerium oxide nanoparticles (CeNPs). The efficient delivery of PTEN plasmid to human prostate cancer cells (PC-3) leads to restoration of the expression of lost PTEN protein in the cell cytoplasm. The delivered superoxide dismutase (SOD)-mimetic CeNPs were also found to decrease the cytoplasmic free radical levels in prostate cancer cells. The above two activities induced DNA fragmentation and micronucleus formation in prostate cancer cells. Furthermore, it was also found that these multifunctional antioxidant nanoliposomes inhibit the PI3K/AKT signaling pathway to negatively regulate the cell viability of prostate cancer cells. The mRNA expression pattern of other relevant proteins predominantly involved in cancer cell proliferation and apoptosis suggested that the high PTEN expression could control the synthesis of oncogenic proteins. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3152-3164, 2018.

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Calcium carbonate micro-and nanoparticles are considered as chemically inert materials. Therefore, they are widely considered in the field of biosensing, drug delivery, and as filler material in plastic, paper, paint, sealant, and adhesive industries. The unusual properties of calcium carbonate-based nanomaterials, such as biocompatibility, high surface-to-volume ratio, robust nature, easy synthesis, and surface functionalization, and ability to exist in a variety of morphologies and polymorphs, make them an ideal candidate for both industrial and biomedical applications. Significant research efforts have been devoted for developing novel synthesis methods of calcium carbonate particles in micrometer and nanometer dimensions. This review highlights different approaches of the synthesis of calcium carbonate micro-and nanoparticles, such as precipitation, slow carbonation, emulsion, polymer-mediated method, including in-situ polymerization, mechano-chemical, microwave-assisted method, and biological methods. The applications of these versatile calcium carbonate micro-and nanoparticles in the biomedical field (such as in drug delivery, therapeutics, tissue engineering, antimicrobial activity, biosensing applications), in industries, and environmental sector has also been comprehensively covered.