The influence of applied positive voltage <i>V</i>₁ on the stable coaxial cone-jet mode and the size of resultant droplets.

<p>(a) Sequence of experimental images showing the stable cone-jet structure changing with <i>V</i>₁; (b) The angle of the cone <i>θ</i> as a function of <i>V</i>₁; (c) The diameter of the resultant droplets <i>D</i>_d as a function of <i>V</i>₁. The applied voltages: <i>V</i>₂ = 1.5 kV, <i>V</i>₃ = -8 kV; The outer liquid: 10.0 w% PLGA (Mw = 10,000) in ethyl acetate solution, <i>Q</i>_out = 1.0 mL/h; The inner liquid: 4.0 w% curcumin and 1.0 w% PLGA (Mw = 50,000) in acetone solution, <i>Q</i>_in = 1.0 mL/h; The vertical distances: <i>h</i> = 0.3 mm, <i>H</i>₁ = 2 mm, <i>H</i>₂ = 20 mm, <i>H</i>₃ = 80 mm.</p

Comparison of the curcumin release profiles versus time at different conditions.

<p>(a) Picture of four samples and schematics of corresponding structures of free curcumin, ES and CES MPs; (b) Drug release profile in 40 days of free curcumin and MPs prepared by ES and CES; (c) The enlarged figure of the release profile in first 12 hours.</p

Experimental CES system for fabricating drug-loaded MPs.

<p>(a) Schematic of the CES setup including a droplet generation module (twin syringe pump, coaxial needle, electrodes with high voltage power supplies and ground), a droplet collection module (collector with magnetic stir bar), and a process monitoring module (light source, microscopic lens combined with CCD camera and computer); (b) Pictures of the inner needle, the outer needle and the assembly of the coaxial needle.</p

Mass production of curcumin-loaded PLGA MPs produced by CES.

<p>(a) SEM imaging and (b) size distribution of the MPs for <i>Q</i>_out = <i>Q</i>_in = 1.0 mL/h; (c) SEM imaging and (d) size distribution of the MPs for <i>Q</i>_out = 1.0 mL/h and <i>Q</i>_in = 0.5 mL/h. The applied voltages: <i>V</i>₁ = 4.8 kV, <i>V</i>₂ = 1.5 kV, <i>V</i>₃ = -8 kV; The outer liquid: 10.0 w% PLGA (Mw = 10,000) in ethyl acetate solution; The inner liquid: 4.0 w% curcumin and 1.0 w% PLGA (Mw = 50,000) in acetone solution; The vertical distances: <i>h</i> = 0.2 mm, <i>H</i>₁ = 2.5 mm, <i>H</i>₂ = 20 mm, <i>H</i>₃ = 80 mm.</p

Core-shell structure of curcumin-loaded PLGA droplets produced by CES.

<p>(a) Confocal fluorescence microscopic image of droplets showing the shell shape (Nile red 0.01 w% in outer liquid); (b) Confocal fluorescence microscopic image of MPs showing the core (I), the shell (II) and the core-shell shapes (III) (Nile red 0.01 w% in outer liquid and coumarin-6 0.01 w% in inner liquid). The applied voltages: <i>V</i>₁ = 4.8 kV, <i>V</i>₂ = 1.5 kV, <i>V</i>₃ = -5 kV; The outer liquid: 10.0 w% PLGA (Mw = 10,000) in ethyl acetate solution, <i>Q</i>_out = 1.0 mL/h; The inner liquid: 4.0 w% curcumin and 1.0 w% PLGA (Mw = 50,000) in acetone solution, <i>Q</i>_in = 0.5 mL/h; The vertical distances: <i>h</i> = 0.2 mm, <i>H</i>₁ = 2 mm, <i>H</i>₂ = 20 mm, <i>H</i>₃ = 80 mm.</p

The stable cone-jet mode and the curcumin-loaded PLGA droplets produced by a CES process.

<p>(a) The morphology of the coaxial cone and the coaxial jet; (b) Microscopic image of curcumin-loaded PLGA droplets directly collected by a glass slide, right after the breakup of the coaxial jet; (c) The size distribution of the collected droplets. The applied voltages: <i>V</i>₁ = 4.8 kV, <i>V</i>₂ = 1.5 kV, <i>V</i>₃ = -8 kV; The outer liquid: 10.0 w% PLGA (Mw = 10,000) in ethyl acetate solution, <i>Q</i>_out = 1.0 mL/h; The inner liquid: 4.0 w% curcumin and 1.0 w% PLGA (Mw = 50,000) in acetone solution, <i>Q</i>_in = 1.0 mL/h; The vertical distances: <i>h</i> = 0.2 mm, <i>H</i>₁ = 2.5 mm, <i>H</i>₂ = 20 mm, <i>H</i>₃ = 80 mm.</p

The influence of outer liquid flow rate <i>Q</i>_out on the stable cone-jet mode and the size of resultant droplets.

<p>(a) Sequence of experimental images showing the stable cone-jet structure changing with <i>Q</i>_out; (b) The angle of the cone <i>θ</i> as a function of <i>Q</i>_out; (c) The diameter of the resultant droplets <i>D</i>_d as a function of <i>Q</i>_out. The applied voltages: <i>V</i>₁ = 4 kV, <i>V</i>₂ = 1.5 kV, <i>V</i>₃ = -5 kV; The outer liquid: 10.0 w% PLGA (Mw = 10,000) in ethyl acetate solution; The inner liquid: 4.0 w% curcumin and 1.0 w% PLGA (Mw = 50,000) in acetone solution, <i>Q</i>_in = 0.2 mL/h; The vertical distances: <i>h</i> = 0.3 mm, <i>H</i>₁ = 2 mm, <i>H</i>₂ = 20 mm, <i>H</i>₃ = 80 mm.</p

Characteristics of Artemether-Loaded Poly(lactic-<i>co</i>-glycolic) Acid Microparticles Fabricated by Coaxial Electrospray: Validation of Enhanced Encapsulation Efficiency and Bioavailability

Artemether is one of the most effective drugs for the treatment of chloroquine-resistant and <i>Plasmodium falciparum</i> strains of malaria. However, its therapeutic potency is hindered by its poor bioavailability. To overcome this limitation, we have encapsulated artemether in poly­(lactic-<i>co</i>-glycolic) acid (PLGA) core–shell microparticles (MPs) using the coaxial electrospray method. With optimized process parameters including liquid flow rates and applied electric voltages, experiments are systematically carried out to generate a stable cone-jet mode to produce artemether-loaded PLGA-MPs with an average size of 2 μm, an encapsulation efficiency of 78 ± 5.6%, and a loading efficiency of 11.7%. The in vitro release study demonstrates the sustained release of artemether from the core–shell structure in comparison with that of plain artemether and that of MPs produced by single-axial electrospray without any relevant cytotoxicity. The in vivo studies are performed to evaluate the pharmacokinetic characteristics of the artemether-loaded PLGA-MPs. Our study implies that artemether can be effectively encapsulated in a protective shell of PLGA for controlled release kinetics and enhanced oral bioavailability

Benchtop and Animal Validation of a Projective Imaging System for Potential Use in Intraoperative Surgical Guidance

<div><p>We propose a projective navigation system for fluorescence imaging and image display in a natural mode of visual perception. The system consists of an excitation light source, a monochromatic charge coupled device (CCD) camera, a host computer, a projector, a proximity sensor and a Complementary metal–oxide–semiconductor (CMOS) camera. With perspective transformation and calibration, our surgical navigation system is able to achieve an overall imaging speed higher than 60 frames per second, with a latency of 330 ms, a spatial sensitivity better than 0.5 mm in both vertical and horizontal directions, and a projection bias less than 1 mm. The technical feasibility of image-guided surgery is demonstrated in both agar-agar gel phantoms and an ex vivo chicken breast model embedding Indocyanine Green (ICG). The biological utility of the system is demonstrated in vivo in a classic model of ICG hepatic metabolism. Our benchtop, ex vivo and in vivo experiments demonstrate the clinical potential for intraoperative delineation of disease margin and image-guided resection surgery.</p></div

The experimental images of the stable cone-jet mode for increasing outer liquid flow rate of (a) 0.5 mL/h, (b) 0.7 mL/h, (c) 0.9 mL/h, (d) 1.1 mL/h.

<p>Inner solution: 50:50 v/v distilled water and EG, 0.5 mL/h; Outer solution: 60 mg/mL PLGA in 50:50 v/v dichloromethane and acetonitrile. The applied electric voltages are +5 kV, +3.5 kV, 0 kV, and -5 kV on the coaxial needle, the ring electrode #1, the ground electrode #2 and the bottom ring electrode #3, respectively.</p