Droplet-based microfluidic method for robust preparation of gold nanoparticles in axisymmetric flow focusing device

A novel microfluidic mixing strategy was developed and used to prepare polyvinylpyrrolidone (PVP) capped gold nanoparticles (AuNPs). In this process, 1 mM tetrachloroauric acid (HAuCl4) stream containing 1% (w/v) PVP was injected through the inner capillary tube and mixed with 20 mM L-ascorbic acid solution delivered co-currently through the outer coaxial capillary. The reaction mixture was hydrodynamically flow focused by the environmentally friendly oil Miglyol 840 delivered from the opposite side of the outer capillary, which resulted in the generation of reaction droplets in a tapered collection tube. The reactants were rapidly mixed within droplets by internal circulating flows induced by hydrodynamic interactions of fluids inside the droplets with the carrier oil. The size of the prepared AuNPs was measured by both dynamic light scattering and transmission electron microscopy and was found to decrease with decreasing the droplet size and increasing the difference in velocity between the two reactant streams, which improved mixing efficiency within droplets. The smallest nanoparticles were obtained when the outlet section of the injection tube was positioned at the entry section of the collection tube due to the highest shear at the liquid interface. The carrier oil formed a hydrophobic barrier between the droplets and the reactor walls preventing deposition of the synthesised particles. As a result, the size of the AuNPs was smaller than in the co-flow mixer operated with two continuous reactant streams

Towards a novel microfluidic device for synthesis of gold nanoparticles for drug delivery

Towards a novel microfluidic device for synthesis of gold nanoparticles for drug deliver

Mixing in microfluidic devices as a new strategy for fabrication of nanoparticles

Mixing in microfluidic devices as a new strategy for fabrication of nanoparticle

Production of biocompatible gold nanoparticles for drug delivery using droplet based glass capillary microfluidic [Abstract]

Production of biocompatible gold nanoparticles for drug delivery using droplet based glass capillary microfluidic [Abstract

Continuous synthesis of PVP stabilized biocompatible gold nanoparticles with a controlled size using a 3D glass capillary microfluidic device

A reliable glass capillary microfluidic method was developed for a continuous production of well-controlled gold nanoparticles (AuNPs) capped with polyvinylpyrrolidone (PVP) of different molecular weights (PVP K15, PVP K30 and PVP K90). A two-phase co-flow glass capillary microfluidic device with an injection orifice diameter ranging between 100 and 240 µm was used to synthesise 100–240 µm was used to synthesise AuNPs via the chemical reduction between tetrachloroaurate trihydrate (HAuCl4·3H2O) and ascorbic acid. AuNPs with an average diameter between 48 and 135 nm were synthesised, as determined by DLS measurements. Decreasing the injection orifice diameter, increasing the flow rate of ascorbic acid stream and its pH resulted in smaller AuNPs. The polydispersity index (PDI) was found to be independent on the injection orifice diameter or the molecular weight of PVP, but increased with the increase of flow rate and the pH of ascorbic acid stream. The stability study over 6-week period confirmed that PVP K30 with an average Mw of 40000 g/mol was the best capping agent to synthesize and stabilise smaller AuNPs. The reactor fouling due to deposition of AuNPs on reactor walls and orifices was mitigated by hydrophobization of reactor/capillary walls with octadecyltrimethoxisilane and the use of ascorbic acid solution of higher pH

Prediction and control of drop formation modes in microfluidic generation of double emulsions by single-step emulsification

Hypothesis - Predicting formation mode of double emulsion drops in microfluidic emulsification is crucial for controlling the drop size and morphology. Experiments and modelling - A three-phase Volume of Fluid-Continuum Surface Force (VOF–CSF) model was developed, validated with analytical solutions, and used to investigate drop formation in different regimes. Experimental investigations were done using a glue-free demountable glass capillary device with a true axisymmetric geometry, capable of readjusting the distance between the two inner capillaries during operation. Findings - A non-dimensional parameter (ζ) for prediction of double emulsion formation mode as a function of the capillary numbers of all fluids and device geometry was developed and its critical values were determined using simulation and experimental data. At logζ > 5.7, drops were formed in dripping mode; the widening jetting occurred at 5 < logζ < 5.7; while the narrowing jetting was observed at logζ < 5. The ζ criterion was correlated with the ratio of the breakup length to drop diameter. The transition from widening to narrowing jetting was achieved by increasing the outer fluid flow rate at the high capillary number of the inner fluid. The drop size was reduced by reducing the distance between the two inner capillaries and the minimum drop size was achieved when the distance between the capillaries was zero

Continuous synthesis of bio-compatible gold nanoparticles using glass capillary microfluidic devices [conference poster]

Continuous synthesis of bio-compatible gold nanoparticles using glass capillary microfluidic devices [conference poster

Production of biocompatible gold nanoparticles using glass capillary microfluidic devices for drug delivery applications - presentation

These are the slides for a paper presented at the Fluid Mechanics of Nanostructructured Materials, 1st Special Interest Group Meeting, 14 September 2017, Queen Mary University of London

Production of biocompatible gold nanoparticles using glass capillary microfluidic devices for drug delivery applications [Powerpoint Presentation]

Production of biocompatible gold nanoparticles using glass capillary microfluidic devices for drug delivery applications [Powerpoint Presentation

Supplementary files for "Continuous synthesis of PVP stabilized biocompatible gold nanoparticles with a controlled size using a 3D glass capillary microfluidic device"

Supplementary files for Continuous synthesis of PVP stabilized biocompatible gold nanoparticles with a controlled size using a 3D glass capillary microfluidic device.<div><br></div><div>Abstract:</div><div>A reliable glass capillary microfluidic method was developed for a continuous production of well-controlled gold nanoparticles (AuNPs) capped with polyvinylpyrrolidone (PVP) of different molecular weights (PVP K15, PVP K30 and PVP K90). A two-phase co-flow glass capillary microfluidic device with an injection orifice diameter ranging between 100 and 240 µm was used to synthesise 100–240 µm was used to synthesise AuNPs via the chemical reduction between tetrachloroaurate trihydrate (HAuCl₄·3H₂O) and ascorbic acid. AuNPs with an average diameter between 48 and 135 nm were synthesised, as determined by DLS measurements. Decreasing the injection orifice diameter, increasing the flow rate of ascorbic acid stream and its pH resulted in smaller AuNPs. The polydispersity index (PDI) was found to be independent on the injection orifice diameter or the molecular weight of PVP, but increased with the increase of flow rate and the pH of ascorbic acid stream. The stability study over 6-week period confirmed that PVP K30 with an average M_w of 40000 g/mol was the best capping agent to synthesize and stabilise smaller AuNPs. The reactor fouling due to deposition of AuNPs on reactor walls and orifices was mitigated by hydrophobization of reactor/capillary walls with octadecyltrimethoxisilane and the use of ascorbic acid solution of higher pH.<br></div