Magnetic hyperthermia in cancer therapy, mechanisms, and recent advances: A review.

Hyperthermia therapy refers to the elevating of a region in the body for therapeutic purposes. Different techniques have been applied for hyperthermia therapy including laser, microwave, radiofrequency, ultrasonic, and magnetic nanoparticles and the latter have received great attention in recent years. Magnetic hyperthermia in cancer therapy aims to increase the temperature of the body tissue by locally delivering heat from the magnetic nanoparticles to cancer cells with the aid of an external alternating magnetic field to kill the cancerous cells or prevent their further growth. This review introduces magnetic hyperthermia with magnetic nanoparticles. It includes the mechanism of the operation and magnetism behind the magnetic hyperthermia phenomenon. Different synthesis methods and surface modification to enhance the biocompatibility, water solubility, and stability of the nanoparticles in physiological environments have been discussed. Recent research on versatile types of magnetic nanoparticles with their ability to increase the local temperature has been addressed.

Synthesis and Application of Carbon Quantum Dots Derived from Carbon Black in Bioimaging.

Carbon quantum dots (CQDs) are a new type of fluorescent QDs that consists mainly of carbon atoms. In this research, CQDs were synthesized through harsh oxidizing conditions applied on carbon black and subsequent N-doping using hexamethylenetetramine (Hexamine) and polyethyleneimine (PEI). The synthesized CQDs were characterized using FTIR, AFM, UV-Visible spectroscopy, photoluminescence (PL) spectroscopy, and fluorescence imaging respectively. The AFM images showed that the dots are in the range of 2-8 nm. N-doping of the CQDs increased the PL intensity. The PL enhancement for the CQDs that were N-doped with PEI was higher compared to those N-doped with hexamine. The shift in PL by changing the excitation wavelength has been attributed to the nano-size of the CQDs, functional groups, defect traps, and quantum confinement effect. The in vitro fluorescence imaging revealed that N-doped CQDs can internalize into the cells and be used for fluorescent cell imaging.

Gadolinium-doped fluorescent carbon quantum dots as MRI contrast agents and fluorescent probes.

In this research passivated gadolinium-doped carbon quantum dots (Gd-doped CQDs) were synthesized from starch by a hydrothermal method. The X-ray diffraction (XRD) pattern of the Gd-doped CQDs showed the formation of highly amorphous carbon. The Fourier transform infrared spectroscopy (FTIR) results suggested that the CQDs are functionalized with C-N and N-H bonds. The synthesized CQDs with a size distribution of 2-8 nm have an absorption peak at 271 nm in UV-Visible spectroscopy (UV-Vis). The photoluminescence (PL) in CQDs was dependent on the excitation wavelength. The QY of the synthesized CQDs was calculated to be 13.2%. The Gd-doped CQDs exhibited sustained PL in ionic solutions with different ionic strengths and different temperatures up to 65 °C. Fluorescence imaging on mouse C34/connective tissue-L929 cells confirmed that Gd-doped CQDs could be well distributed over the cytoplasm. The magnetic resonance imaging (MRI) showed that the Gd-doped CQDs have extremely high longitudinal and transverse relaxivity values of as high as 218.28 mM-1 s-1 and 364.68 mM-1 s-1. The synthesized Gd-doped CQDs are promising candidates as multifunctional imaging probes and MRI contrast agents in biomedical diagnosis and brain mapping applications.

In Vitro Study: Synthesis and Evaluation of Fe3O4/CQD Magnetic/Fluorescent Nanocomposites for Targeted Drug Delivery, MRI, and Cancer Cell Labeling Applications.

In the present study, first, Fe3O4 nanoparticles were functionalized using glutaric acid and then composited with CQDs. Doxorubicin (DOX) drug was loaded to evaluate the performance of the nanocomposite for targeted drug delivery applications. The XRD pattern confirmed the presence of characteristic peaks of CQDs and Fe3O4. In the FTIR spectrum, the presence of carboxyl functional groups on Fe3O4/CQDs was observed; DOX (positive charge) is loaded onto Fe3O4/CQDs (negative charge) by electrostatic absorption. FESEM and AFM images showed that the particle sizes of Fe3O4 and CQDs were 23-75 and 1-3 nm, respectively. The hysteresis curves showed superparamagnetic properties for Fe3O4 and Fe3O4/CQDs (57.3 and 8.4 emu/g). The Fe3O4 hysteresis curve showed superparamagnetic properties (Ms and Mr: 57.3 emu/g and 1.46 emu/g. The loading efficiency and capacity for Fe3O4/CQDs were 93.90% and 37.2 mg DOX/g MNP, respectively. DOX release from Fe3O4/CQDs in PBS showed pH-dependent release behavior where after 70 h at pH 5 and 7.4, about 50 and 21% of DOX were released. Fluorescence images of Fe3O4/CQD-treated cells showed that Fe3O4/CQDs are capable of labeling MCF-7 and HFF cells. Also, T2-weighted MRI scans of Fe3O4/CQDs in water exhibited high r2 relaxivity (86.56 mM-1 S-1). MTT assay showed that DOX-loaded Fe3O4/CQDs are highly biocompatible in contact with HFF cells (viability = 95%), but they kill MCF-7 cancer cells (viability = 45%). Therefore, the synthesized nanocomposite can be used in MRI, targeted drug delivery, and cell labeling.

Preparation and in-vitro evaluation of ß-CD/HA nanocomposite as a potential carrier for hydrophobic drugs.

This study aimed to provide a new drug delivery system for hydrophobic compounds. Dexamethasone (DEX) was employed as a hydrophobic model drug, which incorporated into the network of hydroxyapatite (HA)/Cyclodextrin (ß-CD) nanocomposite. Phase analysis, chemical bonding, morphology, and drug release was evaluated using XRD, FTIR, FESEM, and UV-vis spectroscopy, respectively. XRD patterns showed the formation of the crystalline structure and FTIR analysis showed the chemical bonding between organic and inorganic phases. FESEM images accompanied by EDX analysis confirmed the presence of HA nano-flakes. Release of DEX loaded ß-CD/HA was measured to be around 4.6% and 18.7% in pH5.3 and pH 7.4, respectively. In conclusion, the prepared system could be a potential pH sensitive carrier for sustainable release of water-insoluble drugs.

Effects of Dextran-Coated Superparamagnetic Iron Oxide Nanoparticles on Mouse Embryo Development, Antioxidant Enzymes and Apoptosis Genes Expression, and Ultrastructure of Sperm, Oocytes and Granulosa Cells.

BACKGROUND: Although application of superparamagnetic iron oxide nanoparticles (SPIONs) in industry and medicine has increased, their potential toxicity in reproductive cells remains a controversial issue. This study was undertaken to address the response of sperm, oocyte, and resultant blastocyst to dextran-coated SPIONs (D-SPIONs) treatment during murine in vitro fertilization (IVF). MATERIALS AND METHODS: In this experimental study, murine mature oocytes were randomly divided into three groups: control, and low- and high-dose groups in which fertilization medium was mixed with 0, 50 and 250 µg/ml of DSPIONs, respectively. Sperm and/or cumulus oocyte complexes (COCs) were cultured for 4 h in this medium for electron microscopic analysis of sperm and COCs, and assessment of developmental competence and genes expression of Gpx1, Sod1, catalase, Bcl2l1 and Bax in the resultant blastocysts. RESULTS: Ultrastructural study of sperm, oocyte, and granulosa showed destructed mitochondria and membranes in spermatozoa, vacuolated mitochondria and distorted cristae in oocytes, and disrupted nuclei and disorganized cell membranes in granulosa in a dose-dependent manner. Data showed that cleavage and blastocyst rates in the 250 µg/ml of D-SPIONs were significantly lower than in the control group (P<0.05). Gene expression of GPx1, Sod1, catalase, Bcl2l1 and Bax in resultant blastocysts of the high-dose group and catalase and Bax in resultant blastocysts of the low-dose group, was higher than the controls. CONCLUSION: There is considerable concern regarding D-SPIONs toxic effects on IVF, and mitochondrial and cell membrane damage in mouse spermatozoa and oocytes, which may be related to oxidative stress and apoptotic events.

A review on nanostructured carbon quantum dots and their applications in biotechnology, sensors, and chemiluminescence.

Carbon quantum dots (CQDs) are a member of carbon nanostructures family which have received increasing attention for their photoluminescence (PL), physical and chemical stability and low toxicity. The classical semiconductor quantum dots (QDs) are semiconductor particles that are able to emit fluorescence by excitation. The CQDs is mainly referred to photoluminescent carbon nanoparticles less than 10 nm, with surface modification or functionalization. Contrary to other carbon nanostructures, CQDs can be synthesized and functionalized fast and easily. The fluorescence origin of the CQDs is a controversial issue which depends on carbon source, experimental conditions, and functional groups. However, PL emissions originated from conjugated π-domains and surface defects have been proposed for the PL emission mechanisms of the CQDs. These nanostructures have been used as nontoxic alternatives to the classical heavy metals containing semiconductor QDs in some applications such as in-vivo and in-vitro bio-imaging, drug delivery, photosensors, chemiluminescence (CL), and etc. This paper will introduce CQDs, their structure, and PL characteristics. Recent advances of the application of CQDs in biotechnology, sensors, and CL is comprehensively discussed.

Carbon quantum dots and their biomedical and therapeutic applications: a review.

In recent years, nano carbon quantum dots (CQDs) have received increasing attention due to their properties such as small size, fluorescence emission, chemical stability, water solubility, easy synthesis, and the possibility of functionalization. CQDs are fluorescent 0D carbon nanostructures with sizes below 10 nm. The fluorescence in CQDs originates from two sources, the fluorescence emission from bandgap transitions of conjugated π-domains and fluorescence from surface defects. The CQDs can emit fluorescence in the near-infrared (NIR) spectral region which makes them appropriate for biomedical applications. The fluorescence in these structures can be tuned with respect to the excitation wavelength. The CQDs have found applications in different areas such as biomedicine, photocatalysis, photosensors, solar energy conversion, light emitting diodes (LEDs), etc. The biomedical applications of CQDs include bioimaging, drug delivery, gene delivery, and cancer therapy. The fluorescent CQDs have low toxicity and other exceptional physicochemical properties in comparison to heavy metals semiconductor quantum dots (QDs) which make them superior candidates for biomedical applications. In this review, the synthesis routes and optical properties of the CQDs are clarified and recent advances in CQDs biomedical applications in bioimaging (in vivo and in vitro), drug delivery, cancer therapy, their potential to pass blood-brain barrier (BBB), and gene delivery are discussed.