Microwave Synthesis of Chitosan Capped Silver-Dysprosium Bimetallic Nanoparticles: A Potential Nanotheranosis Device

Fluorescently-tagged magnetic protein nanoparticles for high-resolution optical and ultra-high field magnetic resonance dual-modal cerebral angiography

Extremely small paramagnetic iron oxide nanoparticles (FeMNPs) (<5 nm) can enhance positive magnetic resonance imaging (MRI) contrast by shortening the longitudinal relaxation time of water (T₁), but these nanoparticles experience rapid renal clearance. Here, magnetic protein nanoparticles (MPNPs) are synthesized from protein-conjugated citric acid coated FeMNPs (c-FeMNPs) without loss of the T₁ MRI properties and tagged with fluorescent dye (f-MPNPs) for optical cerebrovascular imaging. The c-FeMNPs shows average size 3.8 ± 0.7 nm with T₁ relaxivity (r₁) of 1.86 mM^-1 s^-1 and transverse/longitudinal relaxivity ratio (r₂/r₁) of 2.53 at 11.7 T. The f-MPNPs show a higher r₁ value of 2.18 mM^-1 s^-1 and r₂/r₁ ratio of 2.88 at 11.7 T, which generates excellent positive MRI contrast. In vivo cerebral angiography with f-MPNPs enables detailed microvascular contrast enhancement for differentiation of major blood vessels of murine brain, which corresponds well with whole brain three-dimensional time-of-flight MRI angiograms (17 min imaging time with 60 ms repetition time and 40 μm isotropic voxels). The real-time fluorescence angiography enables unambiguous detection of brain capillaries with diameter < 40 μm. Biodistribution examination revealed that f-MPNPs were safely cleared by the organs like the liver, spleen, and kidneys within a day after injection. Blood biochemical assays demonstrated no risk of iron overload in both rats and mice. With hybrid neuroimaging technologies (e.g., MRI-optical) on the rise, f-MPNPs built on this platform can generate exciting neuroscience applications.

Multimodal molecular imaging in the second near-infrared window

Near-infrared-II (NIR-II) fluorescence imaging has rapidly developed for the noninvasive investigation of physiological and pathological activities in living organisms with high spatiotemporal resolution. However, the penetration depth of fluorescence restricts its ability to provide deep anatomical information. Scientists integrate NIR-II fluorescence imaging with other imaging modes (such as photoacoustic and magnetic resonance imaging) to create multimodal imaging that can acquire detailed anatomical and quantitative information with deeper penetration by using multifunctional probes. This review offers a comprehensive picture of NIR-II-based dual/multimodal imaging probes and highlights advances in bioimaging and therapy. In addition, seminal studies and trends in multimodal imaging probes activated by NIR-II laser are summarized and several key points regarding future clinical translation are elucidated.

Chitosan-based Dy2O3/CuFe3O4 bio-nanocomposite development, characterization, and drug release kinetics

Chitosan (CS)/metal oxide (MO) nano-carriers have recently attracted attention due to their great integration into several biomedical applications. Herein, CS and dysprosium oxide based bio-nanocomposites (Dy₂O₃/CuFe₃O₄/CS) were prepared using a citrate sol-gel route for biomedical settings at large and drug delivery, in particular. The chemical structure, average crystallite size, and surface morphology of Dy₂O₃/CuFe₃O₄/CS bio-nanocomposites were characterized using spectroscopic techniques, including FT-IR, PXRD, and SEM. The prepared nano composite's drug loading or release kinetics were investigated by FT-IR, zeta potential (ZP), and ultraviolet-visible spectroscopy (UV-Vis). In the FT-IR spectrum, the peaks in the range of 800-400 cm^-1 confirmed the formation of meta-oxides, while amide bands at 1661 and 1638 cm^-1 revealed the existence of CS in the bio-nanocomposite. The peaks at 2θ = 35.46 and 28.5, 39.4 indicated the presence and chemical interaction of Dy₂O₃ and CuFe₃O_4, respectively. The crystallite size was <20 nm. The model drug used in the loading and in vitro release assays was ciprofloxacin hydrochloride. Ciprofloxacin's CF stretch caused a modest peak to be seen at 1082 cm^-1 and changed in zeta potential value from 7.90 mV to 8.88 mV endorsing that the drug had been loaded onto the nanomaterial. The loading efficiency (%) of CIP onto the composite was from 25 to 30 %, calculated from optical density measurements. Different kinetic models, such as zero-order, first-order, Higuchi, Hixon-Crowell, and Korsmeyer-Peppas, were determined to confirm the drug release mechanism. The percent (%) of drug release from the surface of Dy₂O₃/CuFe₃O₄/CS in PBS (pH 7.4), acidic (pH 2.2) and basic (pH 9.4) dissolution media were found to be 70, 28 and 20 %, respectively. Drug kinetics showed that mainly the release is fickian type followed "Fick's law of diffusion", slightly deviated from fickian release (dissolution-dependent system). Korsmeyer-Peppas (R² 0.9773, n < 0.4) and Higuchi's (R² 0.9846) models were the best for fitting controlled drug release data. The results revealed that the Dy₂O₃/CuFe₃O₄/CS bio-nanocomposite has good potential for a controlled drug delivery system.

Anti-microbial and anti-cancer activities of Mn0.5Zn0.5DyxFe2-xO4 (x ≤ 0.1) nanoparticles

Combining two or more nanoparticles is a promising approach. Previously we have reported synthesis of nanoparticles Dysprosium (Dy) substituted with manganese (Mn) zinc (Zn) by using ultrasonication method. The five different nanoparticles (NPs) Mn_0.5Zn_0.5Dy_xFe_2-xO₄ (x ≤ 0.1) have been structurally and morphologically characterized but there is no report on the biological application of these NPs. In the present study, we have examined the anti-cancer, anti-bacterial, and anti-fungal activities of Mn_0.5Zn_0.5Dy_xFe_2-xO₄ (x ≤ 0.1) NPs. Human colorectal carcinoma cells (HCT-116) were tested with different concentrations of NPs by using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. In addition, the impact of NPs was also examined on normal cells such as human embryonic kidney cells, HEK-293. After 48 h of treatment, Mn_0.5Zn_0.5Dy_xFe_2-xO₄ NPs (x = 0.02, 0.04 and 0.06) showed no inhibitory action on cancer cell's growth and proliferation, whereas Mn_0.5Zn_0.5Dy_xFe_2-xO₄ NPs (x = 0.08 and 0.1) showed profound inhibitory action on cancer cell's growth and proliferation. However, the treatment of Mn_0.5Zn_0.5Dy_xFe_2-xO₄ NPs on the normal cells (HEK-293) did not show cytotoxic or inhibitory action on HEK-293 cells. The treatment of Mn_0.5Zn_0.5Dy_xFe_2-xO₄ NPs (x ≤ 0.1) also inhibited both the bacteria (Escherichia coli ATCC35218 and Staphylococcus aureus) with lowest MIC and MBC values of 4 and 8 mg/mL and fungus (Candida albicans) with MIC and MFC values of 4 and 8 mg/mL on treatment with x = 0.08 and 0. 1.

Multifunctional theranostic nanoparticles for biomedical cancer treatments - A comprehensive review

Modern-day search for the novel agents (their preparation and consequent implementation) to effectively treat the cancer is mainly fuelled by the historical failure of the conventional treatment modalities. Apart from that, the complexities such as higher rate of cell mutations, variable tumor microenvironment, patient-specific disparities, and the evolving nature of cancers have made this search much stronger in the latest times. As a result of this, in about two decades, the theranostic nanoparticles (TNPs) - i.e., nanoparticles that integrate therapeutic and diagnostic characteristics - have been developed. The examples for TNPs include mesoporous silica nanoparticles, luminescence nanoparticles, carbon-based nanomaterials, metal nanoparticles, and magnetic nanoparticles. These TNPs have emerged as single and powerful cancer-treating multifunctional nanoplatforms, as they widely provide the necessary functionalities to overcome the previous/conventional limitations including lack of the site-specific delivery of anti-cancer drugs, and real-time continuous monitoring of the target cancer sites while performing therapeutic actions. This has been mainly possible due to the association of the as-developed TNPs with the already-available unique diagnostic (e.g., luminescence, photoacoustic, and magnetic resonance imaging) and therapeutic (e.g., photothermal, photodynamic, hyperthermia therapy) modalities in the biomedical field. In this review, we have discussed in detail about the recent developments on the aforementioned important TNPs without/with targeting ability (i.e., attaching them with ligands or tumor-specific antibodies) and also the strategies that are implemented to increase their tumor accumulation and to enhance their theranostic efficacies for effective biomedical cancer treatments.

One-pot green and simple synthesis of actinian nickel-doped carbon nanoflowers for ultrasensitive sensing of quercetin

In this contribution, a one-pot method possessing the advantages of easy preparation, rapidness, efficiency and environmental friendliness has been developed for the first time for the facile synthesis of highly fluorescent actinian nickel-doped carbon nanoflowers (Ni-CNFWs) by using nickel(ii)acetylacetonate as a metal-carbon source. Various characterization studies indicate that metal nickel atoms have been successfully doped into carbon nanoflower frameworks with a weight percentage of 1.46 wt%. The Ni-CNFWs showed a "shell-core" actinian structure with ∼400 nm diameter and highly efficient fluorescence quenching ability in the presence of quercetin (Qut) due to the formed Meisenheimer complexes via the conjugation effect of p, π-electrons between Ni-CNFWs and Qut, which allowed the analysis of Qut in a very facile method. Under the optimal conditions, the decreased fluorescence of Ni-CNFWs showed a good linear relationship with the concentration of Qut ranging from 0.5 to 300.0 μM, and the limit of detection was 0.137 μM (3σ/k). Finally, the content of Qut in bovine serum was successfully detected with the novel on-off sensor, and the recoveries were 97.3-101.9%, which indicate that the constructed on-off sensor has a high selectivity and accuracy.

Next-generation nanotheranostics targeting cancer stem cells

Cancer is depicted as the most aggressive malignancy and is one the major causes of death worldwide. It originates from immortal tumor-initiating cells called 'cancer stem cells' (CSCs). This devastating subpopulation exhibit potent self-renewal, proliferation and differentiation characteristics. Dynamic DNA repair mechanisms can sustain the immortality phenotype of cancer to evade all treatment strategies. To date, current conventional chemo- and radio-therapeutic strategies adopted against cancer fail in tackling CSCs. However, new advances in nanotechnology have paved the way for creating next-generation nanotheranostics as multifunctional smart 'all-in-one' nanoparticles. These particles integrate diagnostic, therapeutic and targeting agents into one single biocompatible and biodegradable carrier, opening up new avenues for breakthroughs in early detection, diagnosis and treatment of cancer through efficient targeting of CSCs.

Microwave-Driven Synthesis of Iron-Oxide Nanoparticles for Molecular Imaging

Here, we present a comprehensive review on the use of microwave chemistry for the synthesis of iron-oxide nanoparticles focused on molecular imaging. We provide a brief introduction on molecular imaging, the applications of iron oxide in biomedicine, and traditional methods for the synthesis of these nanoparticles. The review then focuses on the different examples published where the use of microwaves is key for the production of nanoparticles. We study how the different parameters modulate nanoparticle properties, particularly for imaging applications. Finally, we explore principal applications in imaging of microwave-produced iron-oxide nanoparticles.

Transition Metal Ion (Mn2+, Fe2+, Co2+, and Ni2+)-Doped Carbon Dots Synthesized via Microwave-Assisted Pyrolysis: A Potential Nanoprobe for Magneto-fluorescent Dual-Modality Bioimaging

Heteroatom-doped carbon dots (C-dots) have captured widespread research interest owing to high fluorescence and biocompatibility for multimodal bioimaging applications. Here, we exemplify a rapid, facile synthesis of ethylenediamine (EDA)-functionalized transition metal ion (Mn²⁺, Fe²⁺, Co²⁺, and Ni²⁺)-doped C-dots via one-pot microwave (MW)-assisted pyrolysis at 800 W within 6 min using Citrus limon (lemon) extract as a carbon source. During MW pyrolysis, the precursor extract undergoes simultaneous carbonization and doping of metal ions onto C-dot surfaces in the presence of EDA. The EDA-functionalized transition metal ion-doped C-dots (i.e., Mn/C, Fe/C, Co/C, and Ni/C-dots) are collectively termed as TMCDs. The water-soluble TMCDs exhibited a size of 3.2 ± 0.485 nm and were enriched with amino and oxo functionalities and corresponding metal-oxide traces on the surfaces, as revealed from Fourier transfer infrared and X-ray photoelectron spectroscopy analyses. Interestingly, TMCDs demonstrated excitation-wavelength-dependent emission with brighter photoluminescence (PL) at 460 nm. Compared to pristine C-dots with a PL quantum yield (QY) of 48.31% and a fluorescence lifetime of 3.6 ns, the synthesized Mn/C, Fe/C, Co/C, and Ni/C-dots exhibited PL QY values of 35.71, 41.72, 75.07, and 50.84% as well as enhanced fluorescence lifetimes (τ_av) of 9.4, 8.6, 9.2, and 8.9 ns, respectively. The TMCDs significantly exhibited enhanced biocompatibility in human colon cancer cells (SW480) for fluorescence bioimaging and showed ferromagnetic and superparamagnetic behavior with vibrant T₁-contrast ability. Interestingly, the maximum longitudinal (r₁) relaxivity of 0.341 mM^-1 s^-1 was observed for Mn/C-dots in comparison to that of 3.1-3.5 mM^-1 s^-1 of clinically used Gd-DTPA magnetic resonance (MR)-contrast agent in vitro (1.5 T). Similarly, the maximum longitudinal relaxivity (r₁) of 0.356 mM^-1 s^-1 was observed for Ni/C-dots (1.5 T) with respect to 4.16 ± 0.02 mM^-1 s^-1 attained for Gd-DTPA in vivo (8.45 T). Thus, the rapid, energy-efficient MW-assisted pyrolysis presents lemon extract derived, EDA-functionalized TMCDs with enhanced PL and efficient T₁ contrast as potential magneto-fluorescent nanoprobes for dual-modality bioimaging applications.

A Bimetallic Silver-Neodymium Theranostic Nanoparticle with Multimodal NIR/MRI/CT Imaging and Combined Chemo-photothermal Therapy

An engineered metallic nanostructure is an excellent candidate for "theranosis" of cancer, having intrinsic properties of multimodal imaging and therapy. Toward this target, the development of silver-neodymium bimetallic nanoparticles (Ag-Nd BNPs) via microwave-assisted polyol synthesis is presented. The resultant Ag-Nd BNPs exhibit good monodispersity with average size of 10 nm, fluorescence in the near-infrared (NIR) region, and magnetic properties. The Ag-Nd BNPs also validate MRI, CT, and NIR trimodal imaging ability and enunciate valuable temperature response upon irradiation under a NIR laser. Aided by chitosan functionalization on the surface, the Ag-Nd BNPs deliver good biocompatibility and also promote the loading of paclitaxel, an anticancer drug. Isothermal titration calorimetry affirms the combination of strong binding affinity of drug and high loading efficiency of 7 drug molecules per nanoparticle. Moreover, Ag-Nd BNPs also illustrate a highly efficient photothermal effect in PBS. Therefore, the synergistic effects of paclitaxel and the photothermal effect make BNPs excellent "combined therapeutic agents", and also give them the important ability to destroy cancer cells in vitro at very low dose in comparison to single therapy. Thus, the Ag-Nd BNPs unveil a combination of MRI/CT/NIR imaging and chemo-photothermal therapy that ensures accurate diagnosis at an early stage and comprehensive eradication of tumor cells without affecting healthy cells.