Seed-mediated synthesis, properties and application of γ-Fe2O3–CdSe magnetic quantum dots

Fe3 O4 @Au@Cu2-x S Heterostructures Designed for Tri-Modal Therapy: Photo- Magnetic Hyperthermia and 64 Cu Radio-Insertion

Here, the synthesis and proof of exploitation of three-material inorganic heterostructures made of iron oxide-gold-copper sulfide (Fe₃ O₄ @Au@Cu_2-x S) are reported. Starting with Fe₃ O₄ -Au dumbbell heterostructure as seeds, a third Cu_2-x S domain is selectively grown on the Au domain. The as-synthesized trimers are transferred to water by a two-step ligand exchange procedure exploiting thiol-polyethylene glycol to coordinate Au and Cu_2-x S surfaces and polycatechol-polyethylene glycol to bind the Fe₃ O₄ surface. The saline stable trimers possess multi-functional properties: the Fe₃ O₄ domain, of appropriate size and crystallinity, guarantees optimal heating losses in magnetic hyperthermia (MHT) under magnetic field conditions of clinical use. These trimers have indeed record values of specific adsorption rate among the inorganic-heterostructures so far reported. The presence of Au and Cu_2-x S domains ensures a large adsorption which falls in the first near-infrared (NIR) biological window and is here exploited, under laser excitation at 808 nm, to produce photo-thermal heat alone or in combination with MHT obtained from the Fe₃ O₄ domain. Finally, an intercalation protocol with radioactive ⁶⁴ Cu ions is developed on the Cu_2-x S domain, reaching high radiochemical yield and specific activity making the Fe₃ O₄ @Au@Cu_2-x S trimers suitable as carriers for ⁶⁴ Cu in internal radiotherapy (iRT) and traceable by positron emission tomography (PET).

Magnetic Fluorescent Quantum Dots Nanocomposites in Food Contaminants Analysis: Current Challenges and Opportunities

The presence of food contaminants can cause foodborne illnesses, posing a severe threat to human health. Therefore, a rapid, sensitive, and convenient method for monitoring food contaminants is eagerly needed. The complex matrix interferences of food samples and poor performance of existing sensing probes bring significant challenges to improving detection performances. Nanocomposites with multifunctional features provide a solution to these problems. The combination of the superior characteristics of magnetic nanoparticles (MNPs) and quantum dots (QDs) to fabricate magnetic fluorescent quantum dots (MNPs@QDs) nanocomposites are regarded as an ideal multifunctional probe for food contaminants analysis. The high-efficiency pretreatment and rapid fluorescence detection are concurrently integrated into one sensing platform using MNPs@QDs nanocomposites. In this review, the contemporary synthetic strategies to fabricate MNPs@QDs, including hetero-crystalline growth, template embedding, layer-by-layer assembly, microemulsion technique, and one-pot method, are described in detail, and their advantages and limitations are discussed. The recent advances of MNPs@QDs nanocomposites in detecting metal ions, foodborne pathogens, toxins, pesticides, antibiotics, and illegal additives are comprehensively introduced from the perspectives of modes and detection performances. The review ends with current challenges and opportunities in practical applications and prospects in food contaminants analysis, aiming to promote the enthusiasm for multifunctional sensing platform research.

Preparation of carbon dots-hematite quantum dots-loaded hydroxypropyl cellulose-chitosan nanocomposites for drug delivery, sunlight catalytic and antimicrobial application

In this project, we studied the thermal and chemical method for the synthesis of carbon dots (CDs)/Hematite (α-Fe₂O₃) quantum dots and the preparation of hydroxypropyl cellulose cross-linked chitosan (HPCCS) and ulvan (UN) was performed by chemical method. Carbon dots/α-Fe₂O₃ quantum dots with size distribution of 3-5 nm were completely encapsulated in the HPCCS/UN NPs to obtain composites, which indicated unique characteristics with respect to antimicrobial, pH-responsive and optical properties. The CDs-HQDs/HPCCS/UN nanocomposites exhibited a single-excitation (440 nm), dual-emission fluorescence property (505 nm and 628 nm for green and red light from CDs-HQDs and HPCCS/UN NPs). The nanocomposites played as a pH-responsive drug delivery process to release ulvan at a fast rate in pH 7.4 buffer solution but at a slow rate in low pH solutions. The CDs-HQDs/HPCCS/UN nanocomposites gained the highest photocatalytic activity for degrading 4-chlorophenol (4-CPh) as a pollutant (>98% during 70 min under sunlight irradiation). Moreover, the nanocomposites indicated great inhibitory influences towards bacterial and fungal.

Designed synthesis and surface engineering strategies of magnetic iron oxide nanoparticles for biomedical applications

Iron oxide nanoparticles (NPs) hold great promise for future biomedical applications because of their magnetic properties as well as other intrinsic properties such as low toxicity, colloidal stability, and surface engineering capability. Numerous related studies on iron oxide NPs have been conducted. Recent progress in nanochemistry has enabled fine control over the size, crystallinity, uniformity, and surface properties of iron oxide NPs. This review examines various synthetic approaches and surface engineering strategies for preparing naked and functional iron oxide NPs with different physicochemical properties. Growing interest in designed and surface-engineered iron oxide NPs with multifunctionalities was explored in in vitro/in vivo biomedical applications, focusing on their combined roles in bioseparation, as a biosensor, targeted-drug delivery, MR contrast agents, and magnetic fluid hyperthermia. This review outlines the limitations of extant surface engineering strategies and several developing strategies that may overcome these limitations. This study also details the promising future directions of this active research field.

Multifunctional PEGylated nanoclusters for biomedical applications

A simple and versatile synthesis method to form water soluble multifunctional nanoclusters using polyethylene glycol (PEG) functionalized poly(maleic anhydride-alt-1-octadecene) amphiphilic brush copolymers (PMAO-g-PEG) was presented. Simply by tuning the core size and the initial nanocrystal concentration, manganese ferrite nanoparticles (MFNPs) were used to demonstrate the versatility of tuning the loading amount of the nanoclusters. The resultant nanoclusters were found to have a well-controlled spherical shape. When Zn-doped AgInS2 quantum dots (AIZS QDs) were loaded together with the MFNP nanocrystals, bi-functional nanoclusters with fluorescent and magnetic behaviors were obtained. Such bi-functional nanoclusters were also successfully demonstrated for cellular bio-imaging. Moreover, the presence of another type of nanocrystals together with MFNPs was found to have a negligible effect on the overall properties of the nanoclusters as demonstrated by the MR relaxivity test. From the time-dependent colloidal stability test, it was found that the presence of the PEG chain grafted onto PMAO was able to reduce protein adsorption onto the nanocluster surface. An in vitro study on NIH/3T3 demonstrated the biocompatibility of the nanoclusters. Such biocompatible and colloidally stable nanoclusters with an approximate size of 80-120 nm were suitable for both MRI and cell labeling applications.