Abraham Wolcott
Owen & Englund Research Group
Department Of Chemistry, APAM and Electrical Engineering
Columbia University
Neuronal Activity Believed to Be
“Emergent”
And BAM Envisions This over a
15 year Plan
Nanodiamond and Neurons at Columbia
University/MIT
What is used
now to image
neurons?
Rafael Yuste- Nueuroscience
Neuronal Staining and Action Potential Measurements
Dirk Englund- Physics
Fluorescent Center Physics (Nitrogen Vacancy Center)
Jonathan Owen- Chemistry
Nanocrystal Surface Science and Modification
+
+
=
State of the Art Neuronal Imaging
Ca2+ Imaging Limitations:
Direct Voltage Imaging :
-Requires Suprathreshold Signals
-Cellular Processes are faster than calcium
dynamics
-Suffers from saturation affects
-Measure the potential of 100 mV over 5 nm=
2*105 V/cm2
- An E-field sensitive chromophore localization is
critical
-- Photodamage of cell membrane is issue
-
The Fluorescent Center in Diamond-The
Nitrogen Vacancy Center
Nitrogen Impurities next to carbon
vacancy
- States: NV+, NV0 and NV-NV-= Ground State Triplet
-
Tracking in cell for over 3 minutes
Chang et al, Mass production and dynamic imaging with fluorescent nanodiamonds, Science, 2008
Hollenberg et al, Nature Nanotechnology, 2011, 6, 358-363
Detection Protocol for Neural
Activity:
Use Phospholipids to
Intercalate Cell
Membrane
 Detect Voltage Drops
Across Cell During
Neural Activity
 100 mV drop over 5
nm (E=200kV/cm)
 Estimated NV E-Field
Resolution 10kV/cm

Proposed Linking Chemistry:
Exploit Carboxylate
Groups
 Synthesize Diaminoethyleneglycol oligomers

Phosphatetriester
Hydrolysis
Phosphatidylethoxyamine
Terminated Surface

Ox. HPHT
NDs
Raman
NEXAFS
FTIR
TEM
NEXAFS/XPS
HPHT Nanodiamonds and Their Purification
Peak(cm-1)
Assignment
ent
1280
111 Dimer mode
& 110 surface
chain mode
1332
 Phonon
mode
1370, 1400
110 Subsurface
Dimer Mode
1620, 1660
Dumbbell
Interstitial,
Oleifinic Chain
Etching of Diamond

C-O Vibrations Dominate DRIFTS
and C=O Sparse
 Found an alcohol rich surface
30:1
Minor
component of higher oxidation
states of carbon (acid anhydrides, acids)
Alcohol:Acid
90:1 Alcohol:Acid After Piranha+Ox
Near Edge X-Ray Absorption Fine
Structure
Probes 1sp-projected
states with  and  symmetry
(1sLUMO)


l= 1 (dipole selection rules)
HPHT : C-O species and Diamond
Readily
see 1Cs
Exciton from
Diamond;Not seen
in Detonation NDs
Can
Identify
LUMO Orbitals with
p-orbitals ( and 
symmetry)
HPHT NDs Similar to Bulk-Like Diamond at
5-50 nm
Direct
Surface
Studies Conclude a
Alcohol Rich
Surface on 111
Minor CO2 Desorption on HPHT NDs Up To
700C Acid Anhydride to
Ketone Vibrational
Signature
HPHT
is High Quality Diamond
Nanoscale Material
But will the HPHT Nanodiamond
 Phononic,
Electronic
and
Support
a Nitrogen
Vacancy Center
Unlike Its Detonation Nanodiamond
Crystallographic
Coherence
Counterpart?
 Alcohol Rich Surface
 Can Be Handled As Powder and As
Colloids
We Have High Quality Diamond:
Leading To Stable NV Centers
Single Quantum Emitter Spin
Manipulation
  t
g1 (t )   Ak exp  
   k
k



k



g 2 (t )  1  g1 t 
2
Optically Detected Magnetic
Resonance (ODMR)
Alternative Linking Chemistry :
Silanization, Amination and Boronation
 Siloxane Chemistry produces
O-Si-O-Si Network + Fxn Group of
Interest
Amination
traditionally uses preChlorination step followed by Amination
(gas phase)
R-BH2 + NDs
Open Challenges In Diamond Chemistry
Very high density of atoms
 C-X bonds should be of
similar atomic radii
 C has diverse bonding
(amorphous carbon)
 Surface chemistry not well
understood

Facet
100
110
111
Carbon
15.8
22.3
18.2
atoms/
nm2
atoms/
nm2
atoms/
nm2
5.41
7.6
6.4
atoms/
nm2
atoms/
nm2
atoms/
nm2
CdSe
Ferrari and Robertson, Interpretation of Raman Spectra of Disordered and Amorphous
Carbon, Phys. Rev. B, 2000
Direct Amination of Surface
50% NH3 atmosphere;
Nitrogen incorporation
significant up to 1100C
-C-H vibrational modes
readily seen in FTIR
R-C=N (Imines at 397)
C=C-R (Pyridine-like at
400 eV)
C-NH2 (405 eV)
Hellgren et al, Nitrogen bonding structure in carbon nitride thin films studied
by soft x-ray spectroscopy, APL, 2001
Diamonds at The Beach: SiO2
Growth
TEOS as a priming
molecule on diamond
with alcohols
Na2SiO3(Liquid Glass) is
then added to increase
SiO2 shell thickness
Decoration with Polyethylene
Glycol as Stabilizer
Why Use SiO2 What
Are the
Advantages???
Before SiO2 plus PEG
After SiO2 plus PEG
Simulations of ND+SiO2+Au NPs (Alex Meng
and Prof. Richard Osgood)
 Fluorescent Center: Nitrogen Vacancy
Center with 6 electron configuration:
 Cube of HPHT
10
Goal:
nm
Simulate the fluorescence
enhancement of a dipole emitter embedded in
a diamond matrix with varying thicknesses of
SiO2 with a Au nanoparticle at its surface.
The
ND with 10nm + SiO2. Under a laser
radiation, due to the high refractive index, the light
can barely get into the nanodiamond.
Plasmon Resonance Produces Electric Field
Enhancement (Antenna Effect)
Au NPs enhance electric field around NVC and enhance
absorption. The excited NV center will now radiate more. However,
a portion of the energy it radiated will be absorbed by gold as
ohmic loss (heat loss/energy transfer).
Dimer Modeling Has Further Enhancement
Au dimer enhances PL further. But more gold
means more energy radiated by NV center will be
absorbed.
NDs@SiO2+Au= Light*7
7
single
dimer
PL Enhancement
6
5
4
3
2
1
0
0
2
4
6
8
SiO Thickness (nm)
10
12
2
The
maximum PL enhancement is at SiO2 = 5nm
PL enhance factor is ~7.
The simulation is performed at 1nm resolution.
Need Controlled Au and ND
HOTSPOT
Interaction
Regional
Control
PL Enhancement Will Take Nanometer
Summary, Conclusions and Musings
HPHT NDs
with
Alcohols
Bulk Like
Material at 530 nm
PL Enhancement with
Au or Biospecific
Labeling (ie.
Neuronal Membrane)
Active
NVC
SiO2 Growth +
Decoration or
Amine Chemistry
Acknowledgements and Thanks:
Edward Chen (MIT)
Prof. Dirk Englund (MIT)
Matt Trusheim (MIT)
Prof. Rafael Yuste (CU)
Chris Dupre (CU)
Prof. Jon Owen (CU)
Alex Meng (CU)
Prof. Richard Osgood (CU)
Dr. Theanne Shiros (CU)
BNL-CFN, NSLS, SSRL,
MRSEC
Dr. Dennis Nordlund (SSRL)
Keck Foundation
Dr. Rosa Diaz (BNL-CFN
MURI
Dr. Darcy Peterka (CU)
EFRC
Dr. Ophir Gaathon (MIT)
Thank You For Your Attention