were, after proper washing to remove the template, mixed with 2-hydroxyethyl
methacrylate and polyethylene glycol diacrylate, which was then polymerized at
low temperature.
Binding of human serum albumin (HSA) to the composite cryogel showed a
clear pH-dependence, which could be correlated to the charges on the HSA
molecule. The MIP was 28 times more efficient at binding HSA than was the NIP
(non-imprinted polymer; the same composition and the same treatment, except for
no exposure to HSA). Adsorption studies revealed that the binding of HSA to the
cryogel followed the Langmuir isotherm. When placing the gel plug in a column
and feeding a solution of HSA continuously, a capacity of 98 mg/g of dry polymer
was reported. This was calculated to be close to the theoretical value for the MIPs
used, 103 mg/g. These values are really astonishing because one might expect steric
hindrance when the MIPs are partially entrapped in a tight polymer network. It was
furthermore reported that when HSA from serum was captured, a maximum
capacity of 683 mg/g of dry gel was obtained. To fully understand the mechanism
behind these very high values, further studies will be needed. Values of capacities
in this range are now matching what is reported for conventional adsorbents.
Composites involving MIPs have been extensively studied and Table 4 lists
some of these systems.
11.1 Applications of MIP-Cryogels in Environmental
Biotechnology
11.1.1 Heavy Metal Ions
Heavy metal ions (HMs) constitute a severe environmental problem. High concentrations in leachates from mining activities are usually treated by precipitation.
However, lower concentrations of HMs can also cause severe problems. This is
seen when water is used for irrigation or when water is consumed. Therefore, it is
attractive to remove HMs almost completely from water. So far, this has not been
possible, even if low levels are reported.
Use of chelating gels for capturing HMs turns out to be efficient [109]. MIPs also
offer interesting alternatives. Chelating groups are not selective; they capture all
heavy metals ions, but with somewhat different efficiencies. It is obvious that there
is competitive binding between different heavy metal ions and the chelating groups.
11.1.2 Endocrine Disruptors
An emerging environmental problem is the presence of physiologically active
compounds in very low concentrations (micrograms per liter or lower). Such
compounds are difficult to degrade in the biological steps in wastewater treatment
Cryogels for Biotechnological Applications
271
methacrylate and polyethylene glycol diacrylate, which was then polymerized at
low temperature.
Binding of human serum albumin (HSA) to the composite cryogel showed a
clear pH-dependence, which could be correlated to the charges on the HSA
molecule. The MIP was 28 times more efficient at binding HSA than was the NIP
(non-imprinted polymer; the same composition and the same treatment, except for
no exposure to HSA). Adsorption studies revealed that the binding of HSA to the
cryogel followed the Langmuir isotherm. When placing the gel plug in a column
and feeding a solution of HSA continuously, a capacity of 98 mg/g of dry polymer
was reported. This was calculated to be close to the theoretical value for the MIPs
used, 103 mg/g. These values are really astonishing because one might expect steric
hindrance when the MIPs are partially entrapped in a tight polymer network. It was
furthermore reported that when HSA from serum was captured, a maximum
capacity of 683 mg/g of dry gel was obtained. To fully understand the mechanism
behind these very high values, further studies will be needed. Values of capacities
in this range are now matching what is reported for conventional adsorbents.
Composites involving MIPs have been extensively studied and Table 4 lists
some of these systems.
11.1 Applications of MIP-Cryogels in Environmental
Biotechnology
11.1.1 Heavy Metal Ions
Heavy metal ions (HMs) constitute a severe environmental problem. High concentrations in leachates from mining activities are usually treated by precipitation.
However, lower concentrations of HMs can also cause severe problems. This is
seen when water is used for irrigation or when water is consumed. Therefore, it is
attractive to remove HMs almost completely from water. So far, this has not been
possible, even if low levels are reported.
Use of chelating gels for capturing HMs turns out to be efficient [109]. MIPs also
offer interesting alternatives. Chelating groups are not selective; they capture all
heavy metals ions, but with somewhat different efficiencies. It is obvious that there
is competitive binding between different heavy metal ions and the chelating groups.
11.1.2 Endocrine Disruptors
An emerging environmental problem is the presence of physiologically active
compounds in very low concentrations (micrograms per liter or lower). Such
compounds are difficult to degrade in the biological steps in wastewater treatment
Cryogels for Biotechnological Applications
271