l ouisiana t ech u niversity college of engineering and science encapsulated silica colloidal...

LOUISIANA TECH UNIVERSITYCollege of Engineering and Science

Encapsulated silica colloidal particles using layer by-layer electrostatic self-assembly of polyelectrolytes and fluorescent dye

Benjamin Holden Department of Biological Engineering, University of Arkansas,

D. Patrick O’Neal, Ph. D. | Biomedical Engineering Department


• Nanoparticles for cancer therapy1. Small >150 nm

2. Highly fluorescent

3. Compatible with drug delivery

Benjamin Holden | Biological Engineering Department University of Arkansas


Flow of particles thru Leaky Vasculature of Tumors

TumorCells

BloodSupply

Normal flow of particles


Nanoparticles with Encapsulated TamoxifenNanoparticles with Encapsulated Tamoxifen

SEM Images: Tamoxifen nanoparticles of approximately (b) 122 and (c) 134 nm after 20 minute sonication in a polycation bath. Samples images are taken 48 hours after LbL process is complete.

Y. Lvov, in collaboration with V. Torchilin



Near-infrared window into tissue

Tissue Optical WindowTissue Optical Window

http://www.ctl.com.pl/art/art4b.html 400 500 600 700 800 900 1000 1100

NIR-664

ICG


• RESEARCH OBJECTIVE – devolve a technique to coat nanoparticles using layer by layer with a fluorescent dye.– Methods

• Adding dye to polyelectrolyte• Layer by layer• Coating a slide• Coating nanoparticles



Problems with ICG

1. Aggregation 2. Solubility 3. Stability4. Photo-bleaching

Benefits of ICG

1. FDA approved2. Inside tissue optical window



Instability of ICG

0.15

0.17

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0.25

0.27

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0.31

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0.35

0 50 100 150 200 250 300

Time (min)

Ab

s

In Dark

In light



+Benjamin Holden | Biological Engineering Department University of Arkansas

-0.5

0

0.5

1

1.5

2

2.5

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3.5

400 500 600 700 800 900 1000 1100

Wavelength (nm)

NIR-664_PDDA

NIR-664-PEI

NIR-664-PAH

-0.05

0

0.05

0.1

0.15

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0.25

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0.35

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Wavelenght (nm)

ICG-P AH

ICG-P DDA

ICG-P E I

Addition of dye to polyelectrolyteAbsorption spectra of ICG-PDDA (blue line), ICG-PEI (red line), and ICG-PAH (black line) in

0.1 M sodium bicarbonate

Absorption spectra of NIR-664-PDDA (blue line), NIR-664--PEI (red line), and NIR-664-PAH (black line) in DI H2O


-0.01

0

0.01

0.02

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0.04

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0.06

400 500 600 700 800 900 1000 1100

Wavelength (nm)

5 layers

4 layers

3 layers

2 layers

Absorption spectra of glass slide with increasing intensity with increasing dye-polyion layers

Glass slide coated with ICG using layer by layer assembly



(a) (b) (c)

(f) (e) (d)


Layer by layer assembly on silica particles


0

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12000

675 685 695 705 715 725 735 745

Wavelen ght ( n m)

NI R_664 Coat 2

NI R-664 Coat 1

Surface Charge

Baseline Layers

≈DiameterBaseline

Layer ≈DiameterH2O sol

- Silica 124 nm Colloidal silica

124 nm

+ PDDA 158 nm PDDA 168 nm

- PSS 160 nm PSS 158 nm

+ PDDA 186 nm PDDA-NIR-664

204 nm

- PSS 191 nm PSS 209 nm

+ PDDA 205 nm PDDA-NIR-664

645 nm

Layer by in DI H2O and NaCl, particle size and surface charge of colloidal silica particles.

Silica particle layer thickness

Silica fluorescence



Discussion

• What are some possible causes for the aggregation of particles?

• Possible solutions for aggregation.



Conclusion

• Objective accomplishments • What’s next?



Questions ?


Acknowledgments

I thank Dr. P. O’Neal for his guidance and many helpful discussions. I would also like to thank Saleh Ramazani and Greg for there help in the day to day operation of my project. Special thanks to Dr Jones, Dr Lvov, and the National Science foundation. I am grateful to the staff of the IFM and BME buildings for the use of there facilities

and equipment

l ouisiana t ech u niversity college of engineering and science encapsulated silica colloidal...

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