Highly stable multi-anchored magnetic nanoparticles for optical imaging within biofilms

Assessing the Biocompatibility of Multi-Anchored Glycoconjugate Functionalized Iron Oxide Nanoparticles in a Normal Human Colon Cell Line CCD-18Co

We have previously demonstrated that iron oxide nanoparticles with dopamine-anchored heterobifunctional polyethylene oxide (PEO) polymer, namely PEO-IONPs, and bio-functionalized with sialic-acid specific glycoconjugate moiety (Neu5Ac(α2-3)Gal(β1-4)-Glcβ-sp), namely GM3-IONPs, can be effectively used as antibacterial agents against target Escherichia coli. In this study, we evaluated the biocompatibility of PEO-IONPs and GM3-IONPs in a normal human colon cell line CCD-18Co via measuring cell proliferation, membrane integrity, and intracellular adenosine triphosphate (ATP), glutathione GSH, dihydrorhodamine (DHR) 123, and caspase 3/7 levels. PEO-IONPs caused a significant decrease in cell viability at concentrations above 100 μg/mL whereas GM3-IONPs did not cause a significant decrease in cell viability even at the highest dose of 500 μg/mL. The ATP synthase activity of CCD-18Co was significantly diminished in the presence of PEO-IONPs but not GM3-IONPs. PEO-IONPs also compromised the membrane integrity of CCD-18Co. In contrast, cells exposed to GM3-IONPs showed significantly different cell morphology, but with no apparent membrane damage. The interaction of PEO-IONPs or GM3-IONPs with CCD-18Co resulted in a substantial decrease in the intracellular GSH levels in a time- and concentration-dependent manner. Conversely, levels of DHR-123 increased with IONP concentrations. Levels of caspase 3/7 proteins were found to be significantly elevated in cells exposed to PEO-IONPs. Based on the results, we assume GM3-IONPs to be biocompatible with CCD-18Co and could be further evaluated for selective killing of pathogens in vivo.

Potential of nano-phytochemicals in cervical cancer therapy

Cervical cancer is common among women with a recurrence rate of 35% despite surgery, radiation, and chemotherapy. Patients receiving chemotherapy or radiotherapy routinely experience several side effects including toxicity, non-targeted damage of tissues, hair loss, neurotoxicity, multidrug resistance (MDR), nausea, anemia and neutropenia. Phytochemicals can interfere with almost every stage of carcinogenesis to prevent cancer development. Many natural compounds are known to activate/deactivate multiple redox-sensitive transcription factors that modulate tumor signaling pathways. Polyphenols have been found to be promising agents against cervical cancer. However, applications of phytochemicals as a therapeutic drug are limited due to low oral bioavailability, poor aqueous solubility and requirement of high doses. Nano-sized phytochemicals (NPCs) are promising anti-cancer agents as they are required in minute quantities which lowers overall treatment costs. Several phytochemicals, including quercetin, lycopene, leutin, curcumin, green tea polyphenols and others have been packaged as nanoparticles and proven to be useful in nano-chemoprevention and nano-chemotherapy. Nanoparticles have high biocompatibility, biodegradability and stability in biological environment. Nano-scale drug delivery systems are excellent source for enhanced drug specificity, improved absorption rates, reduced drug degradation and systemic toxicity. The present review discusses current knowledge in the involvement of phytochemical nanoparticles in cervical cancer therapy over conventional chemotherapy.

Magnetic nanoparticles in cancer diagnosis, drug delivery and treatment

In recent years, magnetic nanoparticles (MNPs) have demonstrated marked progress in the field of oncology. General nanoparticles are widely used in tumor targeting, and the intrinsic magnetic property of MNPs makes them the most promising nanomaterial to be used as contrast agents for magnetic resonance imaging (MRI) and induced magnetic hyperthermia. The properties of MNPs are fully exploited when they are used as drug delivery agents, wherein drugs may be targeted to the desired specific location in vivo by application of an external magnetic field. Early diagnosis of cancer may be achieved by MRI, therefore, individualized treatment may be combined with MRI, so as to achieve the precise definition and appropriate treatment. In the present review, research on MNPs in cancer diagnosis, drug delivery and treatment has been summarized. Furthermore, the future perspectives and challenges of MNPs in the field of oncology are also discussed.

Controlled aggregation and cell uptake of thermoresponsive polyoxazoline-grafted superparamagnetic iron oxide nanoparticles

Hydrophilic polymer-coated iron oxide nanoparticles are potential materials for a plethora of applications in the biotechnological field. Typical such polymers, e.g. dextran or poly(ethylene glycol), lack the ability to tailor the biological response to an environmental trigger, while common responsive polymers such as poly(N-isopropylacrylamide) or poly(acrylic acid) are not suitable for biomedical applications. We present the synthesis and characterization of superparamagnetic iron oxide nanoparticles with thermoresponsive polyoxazoline brushes grafted at unprecedented density using nitrodopamine anchor chemistry. Reversible aggregation/deaggregation is observed in water and biological medium, confirming control over the colloidal stability. Thermal switching of the solubility could only be achieved by global heating of the sample, while local magnetothermal heating did not produce a sufficiently strong temperature gradient through the brush. Varying the polymer composition allows for tuning of the lower critical solution temperature (LCST) as well as the average nanoparticle cluster size obtained upon heating. The LCST of polyoxazolines and the thermal colloidal stability are shown to be greatly affected by ion concentration, by polymer grafting density and also by the presence of serum protein; this shows that transition temperatures of free polymers in water can be very misleading for the design of polymer-coated nanomaterials for biomedical applications. Finally, the thermoresponsive SPION are shown to be non-cytotoxic and with a low cell uptake scaling with the hydration of the polymer brush, which is tuned by the polymer composition. Thus, we demonstrate that pozylated nanoparticles provide the advantages of PEG- and PNIPAM-grafted nanoparticles, but provide a tunable and more easily functionalizable platform for further development.

Quantitative Measurement of Ligand Exchange with Small-Molecule Ligands on Iron Oxide Nanoparticles via Radioanalytical Techniques

Ligand exchange on the surface of hydrophobic iron oxide nanoparticles is a common method for controlling surface chemistry for a desired application. Furthermore, ligand exchange with small-molecule ligands may be necessary to obtain particles with a specific size or functionality. Understanding to what extent ligand exchange occurs and what factors affect it is important for the optimization of this critical procedure. However, quantifying the amount of exchange may be difficult because of the limitations of commonly used characterization techniques. Therefore, we utilized a radiotracer technique to track the exchange of a radiolabeled ¹⁴C-oleic acid ligand with hydrophilic small-molecule ligands on the surface of iron oxide nanoparticles. Iron oxide nanoparticles functionalized with ¹⁴C-oleic acid were modified with small-molecule ligands with terminal functional groups including catechols, phosphonates, sulfonates, thiols, carboxylic acids, and silanes. These moieties were selected because they represent the most commonly used ligands for this procedure. The effectiveness of these molecules was compared using both procedures widely found in the literature and using a standardized procedure. After ligand exchange, the nanoparticles were analyzed using liquid scintillation counting (LSC) and inductively coupled plasma-mass spectrometry. The labeled and unlabeled particles were further characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS) to determine the particle size, hydrodynamic diameter, and zeta potential. The unlabeled particles were characterized via attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and vibrating sample magnetometry (VSM) to confirm the presence of the small molecules on the particles and verify the magnetic properties, respectively. Radioanalytical determination of ¹⁴C-oleic acid was used to calculate the total amount of oleic acid remaining on the surface of the particles after ligand exchange. The results revealed that the ligand-exchange reactions performed using widely cited procedures did not go to completion. Residual oleic acid remained on the particles after these reactions and the reactions using a standardized protocol. A comparison of the ligand-exchange procedures indicated that the binding moiety, multidenticity, reaction time, temperature, and presence of a catalyst impacted the extent of exchange. Quantification of the oleic acid remaining after ligand exchange revealed a binding hierarchy in which catechol-derived anchor groups displace the most oleic acid on the surface of the nanoparticles and the thiol group displaces the least amount of oleic acid. Thorough characterization of ligand exchange is required to develop nanoparticles suitable for their intended application.

Gold nanoparticles: A critical review of therapeutic applications and toxicological aspects

Gold (Au) compounds have been utilized as effective therapeutic agents for the treatment of some inflammatory diseases such as rheumatoid arthritis. However, Au compound use has become limited due to associated high incidence of side effects. Recent development of nanomaterials for therapeutic use with Au-containing drugs is improving the beneficial actions and reducing toxic properties of these agents. Lower toxicity in conjunction with anti-inflammatory and antiangiogenic effects was reported to occur with gold nanoparticles (AuNP) treatment. However, despite this therapeutic potential, safety of AuNP remains to be determined, since the balance between therapeutic properties and development of adverse effects is not well established. Several variables that drive this benefit-risk balance, including physicochemical characteristics of nanoparticles such as size, shape, surface area, and chemistry, are poorly described in the scientific literature. Moreover, therapeutic and toxicological data were obtained employing nonstandardized or poorly described protocols with different experimental settings (animal species/cell type, route and time of exposure). In contrast, effective and safe application of AuNP may be established only after elucidation of various physicochemical properties of each specific AuNP, and determination of respective kinetics and interaction of compound with target tissue. This critical review conveys the state of the art, the therapeutic use, and adverse effects mediated by AuNP, with primary emphasis on anti-inflammatory and antiangiogenic potential, highlighting the limitations/gaps in the scientific literature concerning important points: (i) selection of experimental designs (in vitro and in vivo models) and (ii) consideration of different physicochemical properties of AuNP that are often disregarded in many scientific publications. In addition, prospects and future needs for research in this area are provided.