# Biomedical Applications of Polymeric Cryogels
## 3 Cryogels in Medical Applications
### Capturing of Target Molecules
In a typical molecular imprinting process, the functional monomers and the template molecules are interacted to form complexes and then, the complexes are polymerized with appropriate crosslinkers. After the removal of template molecules selective cavities are obtained which are complementary to template molecules in dimension, shape and functional groups. [PERSON] and co-workers added human serum into the monomer solutions to synthesize molecularly imprinted polymers; thus, some abundant proteins were imprinted in the polyacrylamide cryogels. Albumin, serotransferrin, and most globulins were depleted with the columns packed with the molecularly imprinted polymers. Meanwhile, enrichment of less abundant proteins was carried out. After depletion, less abundant proteins were revealed by SDS-PAGE, peptide fingerprint analysis, and identified by Matrix Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF-MS). This is an example that a \"per se imprint\" protocol enables to gradually dimidiate proteomes, simplify sample complexities, and facilitate further proteome profiling or biomarker discovery [30]. In Table 1 some different technologies for the separation of proteins published were listed. Figure 3: SEM images of PHEMA cryogels (**a**), and SDS-PAGE of IgG separation on the cryogel (Lane 1: Molecular mass markers, Lane 2: After adsorption of human plasma diluted (1/10), Lane 3: Before adsorption human plasma, and Lane 4: Bound eluted fractions (**b**) [29]. Besides the separation and removal of proteins, removal of metal ions plays important role in the treatment of diseases. The toxic effects of many heavy metals are hazardous to human health. Aluminum is a known neurotoxicant which can contribute to Alzheimer's disease [42]. Aluminum enters the brain through the blood-brain barrier, contributing to [PERSON]'s disease and other neurodegenerative diseases. [PERSON] et al. prepared Al(III)-imprinted poly(hydroxyethyl methacrylate-\(N\)-methacryloyl-Lglutamic acid) (PHEMAGA-Al(III)) supermacroporous beads by a suspension polymerization technique for removal of Al(III). They reported maximum Al(III) adsorption capacity as 0.76 mg/g. They also reported relative selectivity coefficients of the PHEMAGA-Al(III) supermacroporous beads for Al(III)/Fe(III), Al(III)/Cu(II) and Al(III)/Zn(II) as 4.49, 8.95 and 32.44 times greater than those of the non-imprinted PHEMAGA beads, respectively. [PERSON] et al. [43] prepared iron imprinted PHEMA cryogel to remove excess Fe(III) ions from beta-thalassemia patient plasma. \(\beta\)-thalassemia is an autosomal recessive disorder characterized by a deficiency in the synthesis of \(\beta\)-chains. Therefore, impaired production of \(\beta\)-chain and unbalanced synthesis of \(\alpha\) and \(\beta\)-chains leads to the destruction of red blood cells (RBCs). Chronic iron overload may occur in thalassemia. Iron intoxication is a life-threatening form of poisoning. They complexed Fe(III) ions with \(N\)-methacryloyl-L-cysteine (MAC) monomer and the resulting MAC-Fe(III) complex were cryopolymerized in the presence of HEMA monomer. They reported maximum Fe(III) adsorption capacity onto cryogel as 75 \(\mu\)g/g. The Fe(III) imprinted poly(hydroxyethyl  
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methacrylate-\(N\)-methacryloyl-l-cysteine (PHEMA-MAC) cryogel was shown to be selective for the Fe(III) ions. They also reported relative selectivity as 10.5 and 2.3 for Fe(III)/Cd(II) and Fe(III)/Ni(II), respectively. The cryogels offer great alternatives via advantages of large pores, short diffusion path, low-pressure drop, and very short residence times for both adsorption and elution. Some different technologies for the removal of metal ions are listed in Table 2. It should be noted that there are many different approaches such as specific interactions, group-specific affinity, and molecular imprinting technology applied to remove metal ions. [PERSON] and co-workers synthesized novel cryogels for the depletion of hemoglobin from human blood.