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Freely suspended cellular "backpacks" lead to cell aggregate self-assembly.

Swiston AJ, Gilbert JB, Irvine DJ, Cohen RE, Rubner MF - Biomacromolecules (2010)

Bottom Line: Cellular "backpacks" are a new type of anisotropic, nanoscale thickness microparticle that may be attached to the surface of living cells creating a "bio-hybrid" material.Previous work has shown that these backpacks do not impair cell viability or native functions such as migration in a B and T cell line, respectively.In the current work, we show that backpacks, when added to a cell suspension, assemble cells into aggregates of reproducible size.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

ABSTRACT
Cellular "backpacks" are a new type of anisotropic, nanoscale thickness microparticle that may be attached to the surface of living cells creating a "bio-hybrid" material. Previous work has shown that these backpacks do not impair cell viability or native functions such as migration in a B and T cell line, respectively. In the current work, we show that backpacks, when added to a cell suspension, assemble cells into aggregates of reproducible size. We investigate the efficiency of backpack-cell binding using flow cytometry and laser diffraction, examine the influence of backpack diameter on aggregate size, and show that even when cell-backpack complexes are forced through small pores, backpacks are not removed from the surfaces of cells.

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Schematic overview of backpack fabrication, including the composition and deposition method for each lamellar region.
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fig1: Schematic overview of backpack fabrication, including the composition and deposition method for each lamellar region.

Mentions: Backpacks were assembled on a glass substrate using a photolithographic lift-off technique.13,14 Photoresist was deposited and patterned with 7 or 15 μm circles on a (PDAC4/SPS4)15.5-coated glass slide, which was then coated using a combination of two different methods. A number of sequential, layer-by-layer (LbL) deposition techniques are possible, including spin assembly,(15) spraying,16−18 and dip-coating deposition.19−21 We used traditional dipping LbL deposition for most regions of the backpack system and an airbrush spraying method to create the backpack’s biodegradable PLGA payload region. PLGA is known as an ideal delivery system as it degrades at physiological conditions into bioresorbable products.(22) We added DiO, a hydrophobic fluorescent dye, to the payload region for visualization. Chloroform was chosen as the mutual PLGA/DiO solvent since it did not dissolve the release region (described below) or the patterned photoresist. We are able to build a functional backpack that contains a PLGA payload, along with any functional component that may be integrated into a PLGA homopolymer film. Traditional LbL dipping was used to build the rest of the backpack. An overview of the backpack fabrication process, including which assembly technique was used for each region, is shown in Figure 1. The thicknesses of each region is approximately 250 nm for the release region, 10 nm for the (PLGA+DiO) payload, 100 nm for the (PAH3.0/MNP4.0)10 region, and 30 nm for the (HA3.0/CHI3.0)3 cell-adhesive strata.


Freely suspended cellular "backpacks" lead to cell aggregate self-assembly.

Swiston AJ, Gilbert JB, Irvine DJ, Cohen RE, Rubner MF - Biomacromolecules (2010)

Schematic overview of backpack fabrication, including the composition and deposition method for each lamellar region.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2903013&req=5

fig1: Schematic overview of backpack fabrication, including the composition and deposition method for each lamellar region.
Mentions: Backpacks were assembled on a glass substrate using a photolithographic lift-off technique.13,14 Photoresist was deposited and patterned with 7 or 15 μm circles on a (PDAC4/SPS4)15.5-coated glass slide, which was then coated using a combination of two different methods. A number of sequential, layer-by-layer (LbL) deposition techniques are possible, including spin assembly,(15) spraying,16−18 and dip-coating deposition.19−21 We used traditional dipping LbL deposition for most regions of the backpack system and an airbrush spraying method to create the backpack’s biodegradable PLGA payload region. PLGA is known as an ideal delivery system as it degrades at physiological conditions into bioresorbable products.(22) We added DiO, a hydrophobic fluorescent dye, to the payload region for visualization. Chloroform was chosen as the mutual PLGA/DiO solvent since it did not dissolve the release region (described below) or the patterned photoresist. We are able to build a functional backpack that contains a PLGA payload, along with any functional component that may be integrated into a PLGA homopolymer film. Traditional LbL dipping was used to build the rest of the backpack. An overview of the backpack fabrication process, including which assembly technique was used for each region, is shown in Figure 1. The thicknesses of each region is approximately 250 nm for the release region, 10 nm for the (PLGA+DiO) payload, 100 nm for the (PAH3.0/MNP4.0)10 region, and 30 nm for the (HA3.0/CHI3.0)3 cell-adhesive strata.

Bottom Line: Cellular "backpacks" are a new type of anisotropic, nanoscale thickness microparticle that may be attached to the surface of living cells creating a "bio-hybrid" material.Previous work has shown that these backpacks do not impair cell viability or native functions such as migration in a B and T cell line, respectively.In the current work, we show that backpacks, when added to a cell suspension, assemble cells into aggregates of reproducible size.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

ABSTRACT
Cellular "backpacks" are a new type of anisotropic, nanoscale thickness microparticle that may be attached to the surface of living cells creating a "bio-hybrid" material. Previous work has shown that these backpacks do not impair cell viability or native functions such as migration in a B and T cell line, respectively. In the current work, we show that backpacks, when added to a cell suspension, assemble cells into aggregates of reproducible size. We investigate the efficiency of backpack-cell binding using flow cytometry and laser diffraction, examine the influence of backpack diameter on aggregate size, and show that even when cell-backpack complexes are forced through small pores, backpacks are not removed from the surfaces of cells.

Show MeSH