Nanoparticle Interactions with Biomolecules: Implications for Disposition

Nanomaterials: Environmental Risks and Benefits and Emerging Consumer Products

NATO-OTAN Advanced Research Workshop

April 27-30, 2008

Alison ElderDepartment of Environmental Medicine,

University of Rochester

Exposures to Nanomaterials: Most Likely Routes

From: Borm et al., 2006

Respiratory tract

GI tract

Skin

Gastrointestinal Tract

• Data suggests that persorption of particles can occur.– Persorption of micron-sized “insoluble” PVC particles

(Volkheimer, 1975).– About 0.0001% Pu dioxide GI tract absorption in humans

(Stather et al., 1979).– No absorption of orally-administered poorly-soluble 15 nm

192Ir particles from GI tract (Kreyling et al., 2002).• Tissue distribution of colloidal Au nanoparticles is

size-dependent following exposures in drinking water for 7 days (Hillyer and Albrecht, 2001).

Does particle density play a role?

Skin Architecture

Basementmembrane

From: Bouwstra et al., 2006

Key Considerations for Studies of Nanomaterials Interactions with Skin

• Surface pH of ~5.0• Lipid lamellae of stratum corneum

Main question: Can nanoparticles breach the stratum corneum and under what conditions?

Tissue Cadmium Content 24 hrs following IntratrachealMicrospray Exposure of Surface-Modified QDots

(Rats, 5 μg Cd sprayed in 3x50 μl)

0.01

0.1

1

10

100

1000

10000

ControlPEGPEG-amine

Note: No Cd was detectable in cerebrum, cerebellum, or olfactory bulbs<L

OQ

<LO

Q

<LO

Q

<LO

Q

<LO

Q

<LOQ <LOQ<LOQ

Carboxyl

Lung HeartBoneMarrow

LiverSpleen KidneyLymphnodes

LavageSup.

LavageCells

Trachea

* *****

**

*

**

p<0.05

**

Cd

Con

tent

, Tot

al n

g

*, vs. control, p<0.05.

Tissue Cadmium Content 24 hrs following IntravenousExposure to Surface-Modified QDots

(Rats, 1.7 μg Cd injected in 200 μl)

0.01

0.1

1

10

100

1000

10000

Lung HeartBoneMarrow

LiverSpleen KidneyLymphnodes

LavageSup.

LavageCells

ControlPEGPEG-amine

<LO

Q

<LO

Q

<LO

Q

<LO

Q

<LO

Q

<LO

Q<LOQ

Blood

<LOQ

*

**#

*

*

*

#

#

#

# #

**

#

**

Carboxyl

Cd

Con

tent

, Tot

al n

g

**

#

*, vs. control, p<0.05;#, vs. all other groups, p<0.05.

Tissue Cd Levels 7 Days after Exposure

Tissue Cadmium Content following IntratrachealMicrospray of Surface-Modified QDots

7 days after Instillation (Rats, 10 μg Cd 3x 150 μl)

Lung Pellet Super Trachea LN-Lung LN-Axil. LN-Illiac Kidney Spleen Liver BM0.01

0.1

1

10

100

Control

100

1000

10000Note: No Cd was detectable in BM, Heart, Blood, Brain tissue

PEG 7DayPEG-amine 7DayCarboxyl 7Day

Cd

Con

tent

, Tot

al n

g

Tissue Cadmium Content following IntraveniousInjection of Surface-Modified QDots

7 days after Injection (Rats, 5 μg Cd 200 μl)

Lung Pellet Super Trachea LN-Lung LN-Axil. LN-Illiac Kidney Spleen Liver BM Heart Blood CSF0.01

0.1

1

10

100

Control

100

1000

10000 Note: No Cd was detectable in cerebrum, cerebellum, or olfactory bulbs

PEG 7DayPEG-amine 7DayCarboxyl 7Day

Cd

Con

tent

, Tot

al n

g

Intratracheal Microspray Intravenous Injection

Liver Cd Levels: Comparison of Exposure Route (and Surface Coating)

0

1000

2000

3000

4000

5000

6000

PEGPEG-amineCarboxyl

Liver Cd Levels following Intravenous Injection of Quantum Dotswith Different Surface Coatings

0 1

Days7

ng C

d

0

50

100

150

Liver Cd Levels following Intratracheal Microspray Delivery of Quantum Dotswith Different Surface Coatings

PEGPEG-amineCarboxyl

1000

1250

1500

1750

2000

ng C

d

0 1

Days7

Intratracheal Intravenous

Tissue Au Content 24 hrs following Intratracheal Microspray Exposure to Colloidal Au Nanoparticles with Different Surface Coatings

0.00

0.05

0.10

0.15

Citrate

PEG 5kSerum albumin

PEG 20k

LALN Bone Marrow BloodSpleen KidneyHeart

0.2

0.3

0.4

0.5

% o

f Adm

inis

tere

d D

ose

(+SD

)

Tissue Au Content 24 hrs following Intravenous Exposure to Colloidal Au Nanoparticles with Different Surface Coatings

0

1

2

3

4

5

Citrate

PEG 5kSerum albumin

PEG 20k

LALN Bone Marrow BloodSpleen KidneyHeart

20

40

60

80

100

120

140

% o

f Adm

inis

tere

d D

ose

(+SD

)

Translocation of Nanogold to the Brain

0.000

0.001

0.002

0.003

0.004

0.005

0.006

Time post exposure

5nm Gold, surface modified:Au in brain after ITM Exposure

1-hour 24-hour

Citrate

PEG 5kSerum albumin

PEG 20k

% o

f Adm

inis

tere

d D

ose

(+SD

)

0.00

0.03

0.06

0.09

0.12

0.15

Time post exposure

5nm Gold, surface modified:Au in brain after IV Exposure

1-hour 24-hour

Citrate

PEG 5kSerum albumin

PEG 20k

% o

f Adm

inis

tere

d D

ose

(+SD

)

Key Cross-Cutting Themes

• Nanoparticle physicochemical characteristics• Properties of portal of entry• Integrity of barrier• Responses caused by NP-cell interactions (e.g.

inflammation) are likely to affect biodistribution

AcknowledgementsAmber Rinderknecht

Nancy CorsonBob GeleinPamela Wade-Mercer

Günter OberdörsterJacob Finkelstein

Grant Support:EPA, NIH/NCIDoD, NSF

Questions?

Summary of Results1. Nanoparticles delivered via the lower respiratory

tract are translocated to extrapulmonary tissues• Dependent on particle physicochemical

characteristics.2. Nanoparticles can be retained in small amounts

by the brain following a single exposure• Dependent on particle physicochemical

characteristics and portal of entry.

Considerations Regarding Nanomaterials Absorption through Skin

• Penetration via hair follicles• Health or condition of skin

– UV radiation, tape stripping facilitate particle access to hair follicles (Sincai et al., 2007; Vogt et al., 2006).

– No penetration without flexion (Tinkle et al., 2003).• Nanoparticle size

– Positively-charged polystyrene beads (20-40 nm) found in follicles at level of epidermis, dermis – particles over 200 nm did not penetrate (Alvarez-Román et al., 2004; Vogt et al., 2007).

– Small percentage of dextran beads penetrate to level of dermis – size cut-off between 1 and 2 μm (Tinkle et al., 2003).

Study Design: Nanoparticle Characteristics

• Characteristics of the QDots:– CdSe/ZnS core-shell particles coated with polymer, ~5

nm core-shell diameter (Invitrogen) – 565 nm emitters– PEG, PEG-amine, or carboxyl conjugated surfaces

• Characteristics of colloidal Au particles:– 5 nm primary particle size (Ted Pella, Inc.)– Coated with albumin, 5 kDa PEG, or 20 kDa PEG

CdSe-ZnS Quantum Dots in 0.9% Saline

PEGylated23 nm

Carboxylated13 nm

PEGamine17 nm

Hydrodynamic Radii of Colloidal Gold Nanoparticles (5 nm)

0

5

10

15

20

25

0.1 1 10 100 1000 10000

Vol

ume

(%)

Size (d.nm)

Citrated AuRSA-AuPEG (5K)-AuPEG (20K)-Au

8 nm19 nm28 nm47 nm

Peak MeanSurface Coating

from: Dr. A. Rinderknecht

Study Design: Nanoparticle Exposures

• Exposures to QDots (dose expressed as Cd content):– Intratracheal microspray (5 μg Cd/150 μl saline)– Intravenous injection (1.7 μg Cd/200 μl saline)

• Exposures to colloidal Au:– Intratracheal microspray (50 μg/150 μl saline)– Intravenous injection (15 μg/200 μl saline)