Magnetite/CdTe magnetic-fluorescent composite nanosystem for magnetic separation and bio-imaging

Magnetic Hydroxyapatite Nanoparticles in Regenerative Medicine and Nanomedicine

This review focuses on the latest advancements in magnetic hydroxyapatite (mHA) nanoparticles and their potential applications in nanomedicine and regenerative medicine. mHA nanoparticles have gained significant interest over the last few years for their great potential, offering advanced multi-therapeutic strategies because of their biocompatibility, bioactivity, and unique physicochemical features, enabling on-demand activation and control. The most relevant synthetic methods to obtain magnetic apatite-based materials, either in the form of iron-doped HA nanoparticles showing intrinsic magnetic properties or composite/hybrid compounds between HA and superparamagnetic metal oxide nanoparticles, are described as highlighting structure-property correlations. Following this, this review discusses the application of various magnetic hydroxyapatite nanomaterials in bone regeneration and nanomedicine. Finally, novel perspectives are investigated with respect to the ability of mHA nanoparticles to improve nanocarriers with homogeneous structures to promote multifunctional biological applications, such as cell stimulation and instruction, antimicrobial activity, and drug release with on-demand triggering.

Corroboration and efficacy of Magneto-Fluorescent (NiZnFe/CdS) Nanostructures Prepared using Differently Processed Core

The selected and controlled preparation of core@shell nanostructures, which unite the multiple functions of ferromagnetic Ni-Zn ferrite core and CdS shell in a single material with tuneable fluorescence and magnetic properties, have been proposed by the seed mediated aqueous growth process. The shell particle thickness and core of nanostructures were precisely tuned. Current work exhibits the comparative study of core@shell multifunctional nanostructures where core being annealed at two different temperatures. The core@shell nanostructure formation was confirmed by complementary structural, elemental, optical, magnetic and IR measurements. Optical and magnetic characterizations were performed to study elaborative effects of different structural combinations of core@shell nanostructures to achieve best configuration with high-luminescence and magnetic outcomes. The interface of magnetic/nonmagnetic NiZnFe₂O₄/CdS nanostructures was inspected. Unexpectedly, in some of the core@shell nanostructures presence of substantial exchange-bias was observed in spite of the non-magnetic nature of CdS QDs which is clearly an “optically-active” and “magnetically-inactive” material. Presence of “exchange-bias” was confirmed by the change in “magnetic-anisotropy” as well as shift in susceptibility derivative. Finally, successful formulation of stable and efficient core@shell nanostructures achieved, which shows no exchange-bias and shift. Current findings suggest that these magneto-fluorescent nanostructures can be used in spintronics; and drug delivery-diagnosis-imaging applications in nanomedicine field.

SERS-fluorescence joint spectral encoded magnetic nanoprobes for multiplex cancer cell separation

A new kind of cancer cell separation method is demonstrated, using surface-enhanced Raman scattering (SERS) and fluorescence dual-encoded magnetic nanoprobes. The designed nanoprobes can realize SERS-fluorescence joint spectral encoding (SFJSE) and greatly improve the multiplexing ability. The nanoprobes have four main components, that is, the magnetic core, SERS generator, fluorescent agent, and targeting antibody. These components are assembled with a multi-layered structure to form the nanoprobes. Specifically, silica-coated magnetic nanobeads (MBs) are used as the inner core. Au core-Ag shell nanorods (Au@Ag NRs) are employed as the SERS generators and attached on the silica-coated MBs. After burying these Au@Ag NRs with another silica layer, CdTe quantum dots (QDs), that is, the fluorescent agent, are anchored onto the silica layer. Finally, antibodies are covalently linked to CdTe QDs. SFJSE is fulfilled by using different Raman molecules and QDs with different emission wavelengths. By utilizing four human cancer cell lines and one normal cell line as the model cells, the nanoprobes can specifically and simultaneously separate target cancer cells from the normal ones. This SFJSE-based method greatly facilitates the multiplex, rapid, and accurate cancer cell separation, and has a prosperous potential in high-throughput analysis and cancer diagnosis.

Magnetic quantum dots in biotechnology--synthesis and applications

Quantum dots (QDs) have great promise in biological imaging, and as this promise is realized, there has been increasing interest in combining the benefits of QDs with those of other materials to yield composites with multifunctional properties. One of the most common materials combined with QDs is magnetic materials, either as ions (e.g. gadolinium) or as nanoparticles (e.g. superparamagnetic iron oxide nanoparticles, SPIONs). The fluorescent property of the QDs permits visualization, whereas the magnetic property of the composite enables imaging, magnetic separation, and may even have therapeutic benefit. In this review, the synthesis of fluorescent-magnetic nanoparticles, including magnetic QDs is explored; and the applications of these materials in imaging, separations, and theranostics are discussed. As the properties of these materials continue to improve, QDs have the potential to greatly impact biological imaging, diagnostics, and treatment.

EGF receptor-targeted nanocarriers for enhanced cancer treatment

The 'nanomedicine' approach has revolutionized cancer therapy by enabling the packaging of therapeutic agents within engineered nanovehicles that can specifically accumulate within the tumor stroma and then be internalized within cancer cells, to render site-selective action while minimizing nonspecific uptake and harmful side effects. While the specific accumulation within the tumor stroma is rendered by the ability of the nanovehicles to passively permeate through the tumor's leaky vasculature, the cellular internalization is often achieved by exploiting receptor-mediated active endocytotic mechanisms using receptor-specific ligand decoration on the vehicle surface. To this end, a highly important receptor found in several cancers is the EGF receptor, which has been implicated in tumor aggression and proliferation. In this context, we provide a comprehensive review of the various approaches of ligand decorations on nanovehicles for active targeting to EGF receptors, and discuss their pros and cons towards optimizing the design of EGF receptor-targeted nanomedicine systems.

CdTe-TiO2 nanocomposite: an impeder of bacterial growth and biofilm

The resurgence of infectious diseases and associated issues related to antibiotic resistance has raised enormous challenges which may possibly be confronted primarily by nanotechnology routes. One key need of critical significance in this context is the development of an agent capable of inhibiting quorum sensing mediated biofilm formation in pathogenic organisms. In this work we examine the possible use of a nanocomposite, CdTe-TiO2, as an impeder of growth and biofilm. In the presence of CdTe-TiO2, scanning electron microscopy (SEM) analysis shows exposed cells without the surrounding matrix. Confocal laser scanning microscopy shows spatially distributed fluorescence, a typical indication of an impeded biofilm, as opposed to the control which shows matrix-covered cells and continuous fluorescence, typical of biofilm formation. Quantitatively, the inhibition of biofilm was ∼57%. CdTe-TiO2 also exhibits good antibacterial properties against Gram positive and Gram negative organisms by virtue of the generation of reactive oxygen species inside the cells, reflected by a ruptured appearance in the SEM analysis.

General one-pot strategy to prepare multifunctional nanocomposites with hydrophilic colloidal nanoparticles core/mesoporous silica shell structure

A general and facile strategy was developed to coat hydrophilic inorganic nanoparticles directly with mesoporous silica nanoparticles (MSNs). The cationic surfactant of cetyltrimethylammonium bromide (CTAB) was adsorbed to various negatively charged CdTe quantum dots, Fe(3)O(4) nanocrystals or Au nanoparticles, introducing the bilayer of CTAB overcoating with positive charge. The subsequent sol-gel reaction of TEOS with the basic catalyst resulted in uniform nanocomposites. The concentration of CTAB and NH(4)OH in the recipe strongly influenced the number of inorganic nanoparticles in the nanocomposites and the homogeneity of MSNs shell. One dimensional Au nanorods and larger size of solid SiO(2) nanoparticles were also able to coat with MSNs using a similar synthetic procedure. The proposed method was greatly simplified without the help of any mediators or silane coupling agents and excellent mesostructural performance was readily achieved. Compared to the methods known from the literatures for the coating of hydrophobic nanoparticles, this efficient way is especially useful for trapping different hydrophilic nanoparticles with arbitrary sizes and shapes into MSNs. These highly versatile multifunctional nanocomposites, together with the pH-responsible drug release behaviors, non-toxicity to normal cells and ease of uptake into cancer cells, are expected to be utilized as drug delivery system for simultaneous imaging and therapeutic applications.

Recent trends in molecular beacon design and applications

A molecular beacon (MB) is a hairpin-structured oligonucleotide probe containing a photoluminescent species (PLS) and a quencher at different ends of the strand. In a recognition and detection process, the hybridization of MBs with target DNA sequences restores the strong photoluminescence, which is quenched before hybridization. Making better MBs involves reducing the background photoluminescence and increasing the brightness of the PLS, which therefore involves the development of new PLS and quenchers, as well as innovative PLS-quencher systems. Heavy-metal complexes, nanocrystals, pyrene compounds, and other materials with excellent photophysical properties have been applied as PLS of MBs. Nanoparticles, nanowires, graphene, metal films, and many other media have also been introduced to quench photoluminescence. On the basis of their high specificity, selectivity, and sensitivity, MBs are developed as a general platform for sensing, producing, and carrying molecules other than oligonucleotides.