g 2 q; t
ð Þ ¼ A 1 þ β g 1 q; t
ð Þ
j
j
2
ð1Þ
where t is the decay time, A is a measured baseline, β is the coherence factor, and
g 1 (q,t) is the normalized first-order electric field time correlation function related to
the measured relaxation rate Γ according to Eq. (2):
g 1 q; t
ð Þ ¼ e
ÀΓt
¼
ð
G Γ
ð Þ e
ÀΓt dΓ
ð2Þ
Deconvolution of the measured intensity autocorrelation was achieved by the
DTS software. For a pure diffusive relaxation, Γ is related to the translational
diffusion coefficient D at q ! 0 and c ! 0 according to Eq. (3):
D ¼ Γ=q
2
ð3Þ
The hydrodynamic radius R h is calculated by the Stokes–Einstein equation as
R h ¼
k B T
.
6πηD
with q, k B , T and η being the scattering vector, the Boltzmann
constant, absolute temperature, and solvent viscosity, respectively. A hydrodynamic radius distribution was calculated from the Laplace inversion of g 1 (t) by
using the CONTIN procedure. Thermoresponsivity of nanogels was investigated
between 10 and 55
C. In order to check the reversibility of the hydrodynamic radius
with temperature transition, five heating and subsequent cooling cycles were
performed. Influence of pH was investigated at 20
C.
2.9 Circular Dichroism Spectroscopy
Circular dichroism (CD) measurements were carried out with an Olis 17 DSM; a
Cary 17 monochromater was used with a spectral output of 184–260 nm. CD
spectra were measured at protein concentrations of 0.5 mg/mL using a cell with
0.090 mm light path in the wavelength range of 190–260 nm, with a bandwidth of
2.00 nm and with number of increments of 50 with an integration time of 20 s at
20
C. CD spectra were expressed in terms of mean residue ellipticity (deg cm
2
dmol
À1 ). The depicted data represent an average of five scans.
2.10 Enzymatic Degradation
Degradation of microgels was investigated in 5 mM elastase in PBS buffer at 37
C
and followed by measuring the hydrodynamic radius of the microgels by dynamic
light scattering (DLS) after every 180 s for a total time of 24 h.
Stimuli-Sensitive Microgels from Native Elastin: An Easy Approach for a Drug. . .
421
ð Þ ¼ A 1 þ β g 1 q; t
ð Þ
j
j
2
ð1Þ
where t is the decay time, A is a measured baseline, β is the coherence factor, and
g 1 (q,t) is the normalized first-order electric field time correlation function related to
the measured relaxation rate Γ according to Eq. (2):
g 1 q; t
ð Þ ¼ e
ÀΓt
¼
ð
G Γ
ð Þ e
ÀΓt dΓ
ð2Þ
Deconvolution of the measured intensity autocorrelation was achieved by the
DTS software. For a pure diffusive relaxation, Γ is related to the translational
diffusion coefficient D at q ! 0 and c ! 0 according to Eq. (3):
D ¼ Γ=q
2
ð3Þ
The hydrodynamic radius R h is calculated by the Stokes–Einstein equation as
R h ¼
k B T
.
6πηD
with q, k B , T and η being the scattering vector, the Boltzmann
constant, absolute temperature, and solvent viscosity, respectively. A hydrodynamic radius distribution was calculated from the Laplace inversion of g 1 (t) by
using the CONTIN procedure. Thermoresponsivity of nanogels was investigated
between 10 and 55
C. In order to check the reversibility of the hydrodynamic radius
with temperature transition, five heating and subsequent cooling cycles were
performed. Influence of pH was investigated at 20
C.
2.9 Circular Dichroism Spectroscopy
Circular dichroism (CD) measurements were carried out with an Olis 17 DSM; a
Cary 17 monochromater was used with a spectral output of 184–260 nm. CD
spectra were measured at protein concentrations of 0.5 mg/mL using a cell with
0.090 mm light path in the wavelength range of 190–260 nm, with a bandwidth of
2.00 nm and with number of increments of 50 with an integration time of 20 s at
20
C. CD spectra were expressed in terms of mean residue ellipticity (deg cm
2
dmol
À1 ). The depicted data represent an average of five scans.
2.10 Enzymatic Degradation
Degradation of microgels was investigated in 5 mM elastase in PBS buffer at 37
C
and followed by measuring the hydrodynamic radius of the microgels by dynamic
light scattering (DLS) after every 180 s for a total time of 24 h.
Stimuli-Sensitive Microgels from Native Elastin: An Easy Approach for a Drug. . .
421