**1. Introduction**

194 Cellulose – Medical, Pharmaceutical and Electronic Applications

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Cellulose, a natural polymer, has been widely used in blood purification due to its good biocompatibility, and excellent processing which can be easily formulated into beads, membranes and hollow fibers. Sorbent-perfusion is a novel approach of blood purification which can specifically remove endogenous and exogenous pathogenic toxins from the blood of patients [1]. The technique involves passing whole blood or plasma of the patient through a cartridge filled with an adsorbent which can easily adsorb the toxin molecules, see **Figure 1 a,b**. According to selectivity, generally adsorbents can be classified as broad spectrum, affinity adsorbents and immuno-adsorbents, of which the latter has the highest selectivity [2-5]. Materials, most commonly used are activated charcoal [6], porous resins and fibers. The pathogenic substances in the blood of patients are adsorbed by the adsorbent via hydrophilic (electro-static forces) or hydrophobic interactions. Macroporous resins usually show high adsorption capacities especially for the removal of high molecular weight or "middle molecules" toxins [7-9].

© 2013 Wang and Yu, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Wang and Yu, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

## **2. Preparation and activation of cellulosic beads**

#### **2.1. Preparation of cellulosic beads [10, 11]**

One hundred grams of cotton (medical grade) was soaked in a flask containing 19% NaOH solution for 3 h at room temperature. The cotton was squeezed and weighed then placed in a 1500 ml conical flask at 25℃ for 3 days. Fifty milliliters of carbon disulfide was added to the conical flask which was then sealed and aged for 5 h to convert the cellulose into a viscose solution, which was then diluted to 1000 ml with 6% NaOH solution to make a 10% viscous solution of cellulose. In a reactor equipped with a stirrer, a mixture of 800 ml chlorobenzene, 200 ml carbon tetrachloride and 2.0 g of potassium oleate was stirred for 30 min at 300 rpm under room temperature. Then 300.0 ml of 10% cellulose viscose solution was added to the reactor slowly and continued stirring for 30 min until the liquid particles were dispersed uniformly. Thereupon, the temperature was slowly raised to 90℃ and kept for 2.5 h, after which it was cooled to room temperature to solidify the liquid particles into resin beads. Cellulosic beads were filtered (20–40 mesh) and washed thoroughly with alcohol and distilled water to remove all the impurities.

Compared to the gel type cellulosic beads, macroporous beads can greatly enhance the adsorption capacity for middle and high molecules in the therapeutic embolization of meningiomas [12-15]. It can be synthesized according to reference [16, 17]. In brief, a certain amount of pore-forming agent such as calcium carbonate granules, with an average diameter of about 0.2mm was added to a 10% viscous solution of cellulose, then mixed and dispersed to form cellulosic beads. After washing with dilute HCl to remove the poreforming agent, various kinds of porous adsorbents could be prepared. Alternatively, macroporous cellulose beads could also be prepared from cellulose solution in ionic liquid by double emulsification [18, 19].

Recently, cellulosic microspheres with a particle size below 5μm have been widely adopted in blood purification [20, 21], which can be an excellent matrix for the preparation of adsorbent.

Bead porosity and density are calculated by the following equations: [10, 17]

$$P = \frac{\rho\_s \times Q}{\rho\_s Q + (1 - Q)\rho\_{H\_2O}} \times 100\% \tag{1}$$

$$D\_P = \frac{wt\_w}{V\_W} \tag{2}$$

Bioactive Bead Type Cellulosic Adsorbent for Blood Purification 197

(4)

OCH2 C

CH2 OCH2CH

OH

OCH2 CH

H

OH

CH2OH

O

CH2

CH2O

Adsorption percentage and capacity can be calculated by the following equations,

*C C AP C*

the volume of plasma used during adsorption.

**2.2. Activation of cellulose beads** 

competes in the reactions, see **Figure 3.**

OH + ClCH2 <sup>C</sup>

ONa + OCH2 <sup>C</sup>

OCH2 C

**Figure 2.** Activation reaction of cellulosic beads

H

O

CH2

H

O

H

O

CH2

NaOH

epoxy reaction

cross linking

ring-opening reaction

[] [] 100%

([ ] [ ] ) *ACC C V B AP* (5)

Where *AP* and *AC* stand for adsorption percentage and adsorption capacity respectively; *[C]B* is the concentration before adsorption, *[C]A* is the concentration after adsorption, *VP* is

Cellulose can be easily activated by reaction with epichlorohydrin which is frequently used for the preparation of cellulosic adsorbent [10,22,23].Briefly, 10 grams of cellulosic beads was activated with 10ml epichlorohydrin in 20ml 2mol/l sodium hydroxide solution. The mixture was stirred at 40℃ for 4 h. Then the epoxy-activated cellulosic beads was washed thoroughly with distilled water and further reacted with amino acids or proteins, see **Figure 2.** The concentration of sodium hydroxide solution used in the condensation reaction plays an important role on the amount of activated expoxy groups linked onto cellulose. This is attributed to the condensation and ring opening reaction of epichlorohydrin molecule that

[ ] *B A B*

$$Q = \frac{\pi v t\_w - \pi v t\_d}{\pi v t\_w} \times 100\% \tag{3}$$

where *P* stands for porosity percentage; *rs* stands for skeleton density; *Q* stands for water content; *ρH2O* stands for density of water; *wtw* stands for weight of wet beads; *wtd* stands for weight of dried beads; *Vw* stands for volume of wet beads; *Dp* stands for packing density.

Adsorption percentage and capacity can be calculated by the following equations,

$$AP = \frac{[\text{C}]\_{\text{B}} - [\text{C}]\_{\text{A}}}{[\text{C}]\_{\text{B}}} \times 100\% \tag{4}$$

$$AC = ([\mathbf{C}\_B] - [\mathbf{C}]\_A) \times V\_P \tag{5}$$

Where *AP* and *AC* stand for adsorption percentage and adsorption capacity respectively; *[C]B* is the concentration before adsorption, *[C]A* is the concentration after adsorption, *VP* is the volume of plasma used during adsorption.

#### **2.2. Activation of cellulose beads**

196 Cellulose – Medical, Pharmaceutical and Electronic Applications

**2.1. Preparation of cellulosic beads [10, 11]** 

**2. Preparation and activation of cellulosic beads** 

alcohol and distilled water to remove all the impurities.

by double emulsification [18, 19].

adsorbent.

One hundred grams of cotton (medical grade) was soaked in a flask containing 19% NaOH solution for 3 h at room temperature. The cotton was squeezed and weighed then placed in a 1500 ml conical flask at 25℃ for 3 days. Fifty milliliters of carbon disulfide was added to the conical flask which was then sealed and aged for 5 h to convert the cellulose into a viscose solution, which was then diluted to 1000 ml with 6% NaOH solution to make a 10% viscous solution of cellulose. In a reactor equipped with a stirrer, a mixture of 800 ml chlorobenzene, 200 ml carbon tetrachloride and 2.0 g of potassium oleate was stirred for 30 min at 300 rpm under room temperature. Then 300.0 ml of 10% cellulose viscose solution was added to the reactor slowly and continued stirring for 30 min until the liquid particles were dispersed uniformly. Thereupon, the temperature was slowly raised to 90℃ and kept for 2.5 h, after which it was cooled to room temperature to solidify the liquid particles into resin beads. Cellulosic beads were filtered (20–40 mesh) and washed thoroughly with

Compared to the gel type cellulosic beads, macroporous beads can greatly enhance the adsorption capacity for middle and high molecules in the therapeutic embolization of meningiomas [12-15]. It can be synthesized according to reference [16, 17]. In brief, a certain amount of pore-forming agent such as calcium carbonate granules, with an average diameter of about 0.2mm was added to a 10% viscous solution of cellulose, then mixed and dispersed to form cellulosic beads. After washing with dilute HCl to remove the poreforming agent, various kinds of porous adsorbents could be prepared. Alternatively, macroporous cellulose beads could also be prepared from cellulose solution in ionic liquid

Recently, cellulosic microspheres with a particle size below 5μm have been widely adopted in blood purification [20, 21], which can be an excellent matrix for the preparation of

> (1 ) *s s H O*

> > *wt <sup>D</sup>*

*P*

2

*w*

*W*

*w d* 100% *w wt wt <sup>Q</sup> wt*

where *P* stands for porosity percentage; *rs* stands for skeleton density; *Q* stands for water content; *ρH2O* stands for density of water; *wtw* stands for weight of wet beads; *wtd* stands for weight of dried beads; *Vw* stands for volume of wet beads; *Dp* stands for packing density.

  100%

(1)

*<sup>V</sup>* (2)

(3)

Bead porosity and density are calculated by the following equations: [10, 17]

*<sup>Q</sup> <sup>P</sup> Q Q* 

Cellulose can be easily activated by reaction with epichlorohydrin which is frequently used for the preparation of cellulosic adsorbent [10,22,23].Briefly, 10 grams of cellulosic beads was activated with 10ml epichlorohydrin in 20ml 2mol/l sodium hydroxide solution. The mixture was stirred at 40℃ for 4 h. Then the epoxy-activated cellulosic beads was washed thoroughly with distilled water and further reacted with amino acids or proteins, see **Figure 2.** The concentration of sodium hydroxide solution used in the condensation reaction plays an important role on the amount of activated expoxy groups linked onto cellulose. This is attributed to the condensation and ring opening reaction of epichlorohydrin molecule that competes in the reactions, see **Figure 3.**

ring-opening reaction

**Figure 2.** Activation reaction of cellulosic beads

Bioactive Bead Type Cellulosic Adsorbent for Blood Purification 199

Shenqi Wang and Yaoting Yu et al [24] studied the mechanism of recognition and interactions of low density lipoprotein cholesterol(LDL-C) with different charged ligands on the adsorbents. Tryptophan, lysine residues and carboxyl terminus on LDL were chemically modified by PP,EDC and NBS respectively. Due to the effectiveness of L-lysine in the removal of LDL-C, it was selected to study the interaction of ligand with the modified LDL. Experimental results show that positive charge on the surface of LDL interacted with the negatively charged carboxyl groups of L-lysine by electrostatic force, thus resulting in the adsorption of LDL by the absorbent. We also found that increasing the positive charge on the surface of LDL could enhance the adsorption capacity of the adsorbent. On the contrary, increasing the negative charge could decrease the adsorption ability. Thus, different adsorbents containing sulfonic groups, phosphoric groups, L-lysine and carboxyl groups as the ligand were synthesized for investigating the effect of electric charge on their adsorption capacity. Results show that the adsorption capacity increases with the increase of

TC LDL-C

Adsorption percentage (%) Adsorption capacity (mg/ ml)

Adsorption capacity (mg /ml)

―SO3 2- 52.58 1.998 60.9 1.432 ―PO4 3- 43.86 1.667 44.25 1.039 PP―PO4 3- 40.39 1.535 39.51 0.928 DNA―PO43- 34.94 1.328 33.14 0.778 L-lysine―COO - 31.68 1.203 27.98 0.657 ―COO - 26.02 0.989 13.75 0.323

**Table 1.** Adsorption capacity and percentage of total cholesterol(TC), LDL-C by cellulosic beads having

0.778

123456

3- PP-PO4

3- -PO4

3- -SO3 2-

Electronegativity of ligands immobilized on the addsorebnt

**Figure 4.** The relationship of absorption capacity versus electronegativity of ligands immobilized on the

0.928

1.039

1.432

the electro-negativity of the ligand on the adsorbent. See **Table1**

Adsorption percentage (%)

Source: Wang S Q et al, Reactive & Functional Polymers (2008), 68: 261-267

0.323

(From Wang S Q et al, Reactive & Functional Polymers (2008), 68: 261-267, adapted)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Adsorption capacity(mg/ml)

0.657


Terminus group of adsorbent

different terminus groups

adsorbent

**Figure 3.** Amount of epoxy groups on cellulose versus concentration of NaOH
