Formation of Biological Formation of Biological Microspheres Using Ink Microspheres Using Ink

Jetting and Laser TransferJetting and Laser Transfer

Yong HuangYong Huang

Associate Professor of Mechanical EngineeringAssociate Professor of Mechanical Engineering

Adjunct Associate Professor of BioengineeringAdjunct Associate Professor of Bioengineering

Clemson University, Clemson, SC 29634Clemson University, Clemson, SC 29634

http://http://www.ces.clemson.edu/camsilwww.ces.clemson.edu/camsil//

2

Background

Fabrication Methods

Results and Conclusions

Summary and Future Collaborations

Acknowledgements

Outline

3

Introduction and Motivation

Biomedical applications of microspheres:

Controlled drug/cell delivery

Cell encapsulation for transplantation

Cellular spheroid-based tissue engineering

Challenges in microsphere fabrication

Formability of size controllable microspheres using various low and high low and high viscosity biological materialsviscosity biological materials

Monodisperse distribution of fabricated microspheres

Matrix material

(polymer)

Encapsulated materials (drug or cell)

MicrosphereMicrosphere

4

Nozzle jetting-based

Nozzlelessjetting-based

Potential Fabrication Technologies

Clog freeGood for viscous materials

Size controllabilityGood for low viscosity

materials

Ink jetting (thermal and piezoelectric)

Modified LIFT (Laser-InducedForward Transfer)

5

Background

Fabrication Methods

Results and Conclusions

Summary and Future Collaborations

Acknowledgements

Outline

6

1. Vibration-Assisted Ink Jetting

Fluid reservoir

Nozzle

Air gapMicrospheres

Orifice

Pressure pulse via piezoelectric

device

Chamber with liquid solution

Piezoelectrictransducer

Stir bar

Dd

Nd

Drop-on-demand jetting schematic

For low viscosity materials

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2. Modified LIFT (Laser)

Workpiece/substrate Vacuum

chuck

Quartz

DemagnifiedUV laser pulse

System setup

Transparent quartz support

Cell/protein coating

Optional energy conversion layer

MechanismMechanism

Focused UV laser pulse

Excimer UV laser pulse (12 ns)

Objective

Laser pulse

Flexible foil

Forming dropletCells

Adhesive conversion

layer

Quartz support

CaCl2 solution

Direct-writing height

NaAlg suspension

Proposed metallic foil-assisted LIFT

For high viscosity materials

8

Background

Fabrication Methods

Results and Conclusions

Summary and Future Collaborations

Acknowledgements

Outline

9

Vibration-Assisted Inkjet-Based MethodF

orm

abili

ty

Sodium alginate concentration (%)

100 µm

100 µm

100 µm

Goo

dB

ad

Microsphere formability as a function of sodium alginate concentration (and other operating conditions)

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(cont’d)

100 µm

Encapsulated fluorescent beads

Microspheres (alginate-based)

Encapsulated monodisperse microsphere can be formed as a function of sodium alginate concentration

and other operating conditions

Vibration-Assisted Inkjet-Based Method

11Effect of NaAlg concentration

Sodium alginate (NaAlg) concentration: (A) 2 %; (B) 4 %; (C) 6 %(w/v) under laser fluence: 3858±34 mJ/cm2

NaAlgconcentration

Size uniformity

Microsphere size

A B C

Slightly

Laser-Based Method

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A

C

B

D

Laser fluence Number of

satellite droplets

Microsphere size

Effect of laser fluence

Laser fluence: (A) 2030±29; (B) 3858±34; (C) 5734±43; (D) 7436±48 mJ/cm² uisng 6 % (w/v) NaAlg solution

Laser-Based Method (cont’d)

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Using modified LIFT Using proposed metallic foil -assisted LIFT

2 % (w/v) NaAlg solution with 1.8 ×106 beads/ml

Laser-Based Method (cont’d)

Better encapsulation effect using proposed metallic foil-assisted LIFT (laser-based)

14

Background

Fabrication Methods

Results and Conclusions

Summary and Future Collaborations

Acknowledgements

Outline

15

Summary Encapsulated biological microspheres can be effectively fabricated

using proposed vibration-assisted ink jetting (for low viscosity materials) and laser transfer (for high viscosity materials) based approaches

Future work - size control and size distribution control (monodispersity)

Future collaborations envisioned Encapsulated microspheres for controlled drug delivery

Tissue microspheroids for cell transplantation and organ printing

Encapsulated cellular microspheroids for controlled stem cell differentiation study under matrix material-defined microenvironments

More …

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Background

Fabrication Methods

Results and Conclusions

Summary and Future Collaborations

Acknowledgements

Outline

17

Acknowledgements

Financial support: the National Textile Center, the National Science Foundation (CMMI-CAREER and EPS), the National Institutes of Health (P20), and the South Carolina EPSCoR/IDeA office (CCD grant).

Special thanks: Dr. Scott Little of the State EPSCoRoffice, Dr. Douglas B. Chrisey of RPI, Drs. Roger Markwald, Vladimir Mironov, and Joann Sullivan of MUSC, and Dr. Jeremy Tzeng of Clemson

Students: Yafu Lin, Leigh Herran, Wei Wang, Nicole Coutris, and Wenxuan Chai