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In this paper, a miniature fluidic synthesis platform utilizing millimeter dimension channels for the synthesis of cadmium sulfide (CdS) quantum dots and nanocrystals is demonstrated. Traditional nanoparticle synthesis techniques involve macroscopic flasks where reaction conditions may vary at different positions inside the vessel. Therefore challenges in terms of batch reproducibility for large scale production are of great concern. Here, we show that it is possible to replicate reaction conditions so as to produce nanoparticles with similar optical characteristics across different batches using the same reaction parameters. Particle size control was established by varying the flow rate of the precursors, yielding gradually increasing nanocrystal sizes from 2.4 nm to 3.7 nm with increasing residence time. The as-synthesized CdS nanoparticles exhibited tunable photoluminescence by adjusting the molar ratio of the cadmium and sulfur precursors, giving rise to greenish-blue and orange-red emissions under ultraviolet light illumination. The particles were then studied and characterized using transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) absorbance, photoluminescence, X-ray diffraction (XRD) and selected area electron diffraction (SAED) techniques. Lastly, bioimaging of RAW264.7 mice macrophage cells using ligand exchanged CdS nanoparticles is presented.

Correction for ‘Millifluidic synthesis of cadmium sulfide nanoparticles and their application in bioimaging’ by Liying Hong, Tai-Lok Cheung et al., RSC Adv., 2017, 7, 36819–36832.

Due to the high demand for near infrared (NIR) optical nanoprobes, with emissions which are absorbed to a lesser extent by biological tissues, for diagnosing diseases (e.g. cancer) which occur under deep tissue, we present a one-pot synthesis of highly monodispersed (full width at half maximum: 70 nm) NIR core–shell type II CdTe–CdS quantum dots (QDs), encapsulated in a highly biocompatible polymer, for in vivo sentinel lymph node and tumour imaging.

Quantum dots (QDs) exhibit unique optical properties including size-tunable fluorescence, superior brightness, broad absorption and tiny emission bandwidth. These properties have made QDs promising candidates for bioimaging and biosensing applications. In this work, CdTe QDs were synthesized in aqueous phase using both mercaptopropionic acid (MPA) and Cysteine (Cys) as capping agents. Growth kinetics and optical properties of the resulted QDs were found to be dependent on both species and concentration of surfactant molecules. Considering the distinct nature and advantages of MPA and Cys, a mixed-ligands system was proposed as a potential approach to fabricate QDs with specific optical property and functions for in vitro and in vivo bioimaging applications.

In this paper we report the development of multifunctional nanoprobes based on InP–ZnS quantum dots (QDs) for high contrast multimodal imaging and other applications for cancer in vitro and in vivo. These theranostic nanoprobes were synthesized by co-encapsulating InP–ZnS QDs and anticancer drug molecules within PEGylated phospholipid micelles covalently linked with DOTA-chelated Gd3+. Luminescent biocompatible InP–ZnS QDs and Gd3+ chelates can be used for fluorescence microscopy and magnetic resonance imaging (MRI), respectively. The nanoprobes showed both optical and MRI capabilities. The therapeutic effect of the theranostic nanoprobes was evaluated using cell viability assays and the toxic effect of the released anticancer drugs from the probes was confirmed on the cancer cells. For targeted delivery in vitro, the micelle-encapsulated QDs were conjugated with transferrin and anti-claudin-4 antibody, which target the transferrin- and claudin-4-receptors overexpressed in cancer cells, respectively. Employing in vivo optical imaging of mice bearing pancreatic cancer xenografts, we have demonstrated that systemically-delivered anti-claudin-4 conjugated QD nanoprobes can target and label the tumors with high contrast. These studies suggest that the developed theranostic InP–ZnS QD nanoprobes have the potential to be translated in clinical research for targeted multimodal diagnosis and therapy of cancer.