4. The T g at each drying point can be estimated by using a
Gordon-Taylor fit for trehalose-water data according to:
T g ¼
1 À x
ð
ÞT g,Tre þ kxT g,w
1 À x
ð
Þþkx
where x is the mass fraction of water, k ¼ 5.2, T g , Tre (T g of
trehalose) is 100
C, and T g,w (T g of water) is À135
C [32].
Table 2
Comparison of the main parameters used for microwave- and laser-assisted drying of different types
of biologics
Microwave-assisted
drying
Laser-assisted
drying
J774.A1 mouse
macrophage cells
Feline germinal
vesicle oocytes
Feline
sperm
Proteins
Instruments
parameters
Full power of 600 W 20% power, SAM
255 microwave
(108 Æ 7 W)
1064 nm laser
at 5 W
Trehalose
solution
preparation
200 mM trehalose
in 1Â PBS buffer
solution
1.1 M trehalose
in Tris-EDTA
buffer
solution
0.3 M trehalose
in Tris-EDTA
buffer
solution
0.2 M trehalose
in 0.33 Â PBS
Trehalose
loading
Fluid phase
endocytosis
10 μg/mL
α-hemolysin
0.5 mg/mL αhemolysin
Dissolved in
trehalose
solution at a
concentration
of 0.5 mg/mL
Volume of
each sample
20 μL droplet
40 μ droplet
40 μL droplet
40 μL droplet
Substrate
22 mm square plastic
over slips
13 mm fiber
filter
13 mm diameter
Thermanox
plastic
coverslips
18 mm diameter
borosilicate glass
coverslips
Drying time
and its
predicted T g
7 min drying
(30 s active heating
period/30 s rest)
to achieve 4.3 g
H 2 O/g DW
(see Note 1)
30 min drying
to achieve
T g ¼ 26.3
C
30 min to
achieve
T g ¼ À7
C
60 min to achieve
T g ¼ À10.3
C
Relative
humidity
Uncontrolled
RH in the range
of 19–22%
1.1 M trehalose
in Tris-EDTA
buffer
solution
0.3 M trehalose
in Tris-EDTA
buffer
solution
1064 nm laser
at 5 W
214
Shangping Wang et al.