Vaccination of Biological Cellulose Fibers with Glucose: A Gateway to Novel Nanocomposites

This work introduces, for the first time worldwide, the means to preserve and protect the natural nanoporous structure of the never-dried plant cell wall, against the irreversible collapse which occurs due to drying. Simultaneously, these means, used for the above-mentioned aim, provide a gateway to novel nanocomposite materials, which retain the super reactive and super absorbent properties of the never-dried biological cellulose fibers. The present work showed, for the first time worldwide, that glucose can be vaccinated into the cell wall micropores or nanostructure of the never-dried biological cellulose fibers, by simple new techniques, to create a reactive novel nanocomposite material possessing surprising super absorbent properties. Inoculation of the never dried biological cellulose fibers, with glucose, prevented the collapse of the cell wall nanostructure, which normally occurs due to drying. The nanocomposite, produced after drying of the glucose inoculated biological cellulose, retained the super absorbent properties of the never dried biological cellulose fibers. It was found that glucose under certain circumstances grafts to the never dried biological cellulose fibers to form a novel natural nanocomposite material. About 3-8% w/w glucose remained grafted in the novel nanocomposite. novel nanocomposite, produced from the cellulose fibers vaccinated with finds of super absorbent natural fibers for hygienic purposes cellulosic source. Such uses


Introduction and Object :-
Never dried cotton has -for the first time-been isolated from mature green unopened cotton bolls and chemically purified, by us, while it is still in its biological wet state. It was, also, characterized regarding its crystallinity and porosity (1)(2). We further described the use of never dried cotton for preparation of unique cellulose derivatives (3)(4).
In the never dried water-saturated state, cell walls of mature cotton fibers consist of unassociated individual elementary fibrils termed protofibrils of the magnitude 35Å (3.5nanometer). Based on an interpretation of cellulose density measured in water, it has been concluded that the protofibril consists of incompletely crystalline cellulose. When the cell wall dries, protofibrils agglomerate together and cellulose simultaneously becomes almost entirely crystalline (1)(2).
Drying leads to the collapse of the natural nanostructure of the plant cell wall of never dried biological cellulose fibers. Consequently, drying causes the loss of the super absorbent and super reactive properties of the never dried biological cellulose fibers.
The present work is a serious interesting attempt to study how to preserve and protect the original natural nanostructure, of the never-dried biological cotton fibers, against cell wall collapse caused by nature airdrying. It is thought and planned to try special nanoadditves, the building units of the cellulose namely glucose, for this purpose. p 4 of 16 tp Glucose, being the building unit of cellulose and having a suitable size, enters into most of the nanopores of the cell wall of biological cellulose and is entrapped and engrafted easily. When aqueous solutions of glucose are equilibrated with never-dried pulp, the glucose should be able to penetrate into every micropore or nanopore larger than 8 Å (0.8 nanometer), the volume of these glucose accessible pores amounts to 88% of the total pore volume of the micropores. Thus the dissolved glucose molecules should be distributed rather uniformly throughout the fiber cell wall, except for the pores less than 8 Å in size. These The biological cotton used in the present study contained about 63% moisture content when picked from the unopened green cotton bolls.
It was purified, without any previous drying, to 99.6% alpha cellulose.
All the purification steps were carried out without any drying, using a solvent exchange technique (1). The purified biological cellulose fibers were stored immersed in water. A part of the purified biologically swollen fibers were left to dry in air till equilibrium moisture content was reached, which amounted to 6.8%.
Starting from the biologically swollen state, changes in fine structure of the isolated mature cotton fibers -due to drying -were traced by means of p 6 of 16 tp centrifugal water retention value (WRV), and also by density measurements. The results are reported in Table 1.
Several theories about the fine structure of fibers have been presented (5)(6)(7)(8). Such theories about cellulose structure are based on X-ray analysis and electron microscopy. These tools are only applicable to fibers in the dry state (9). Cellulose fibers are, however, worked up in water-swollen state in most industrial processes. In papermaking, all operationstill the last stage of drying the paper sheetare carried out while the fibers are saturated with water. For chemical conversion usually the cellulose fibers have to be pre-swollen with water or other liquids before being subjected to the chemical reaction. Therefore the fine structure of the swollen, respectively water-saturated fibers could be of more bearing on fiber behavior in papermaking and during chemical conversion than the fine structure of dry fibers. Accordingly, the fine structure of fibers in the water-saturated state has attracted the attention of research workers (9). Density measurements were adopted for studying the fine structure of both the dried and the never-dried water saturated states (1); and the interpretation of densities in terms of fiber crystallinity and porosity are laid down. Water uptake can be determined for fibers in both the water-saturated and the dried states. Water uptake can be correlated to pore volume of the swollen cell wall. Accordingly, water p 7 of 16 tp retention value (WRV) was adopted in the present work for studying the fine structure of the swollen and dried cell wall.
A high fiber saturation point (FSP) i.e. WRV of about 120% is ascribed to pure cellulose nature fiber in the never-dried biological state, irrespective of plant origin, as well as to never-dried regenerated cellulose (4).
Consequently, it is clear from Table 1 that water treatment of the air dried cotton fibers -to determine their WRV and density-failed to return the cell wall to its original biological volume, as measured by FSP (WRV). This shows that the basic morphological structural element in air-dry fibers is not the original protofibril but predominantly an aggregate of closely associated microfibrils i.e. compound microfibril. It is, also, clear from Table 1 that drying of the biological cellulose fibers to practically zero moisture content -via oven drying-decreased both the density and the WRV. This is attributed to formation of enclosed pores.
Fahmy and Mobarak were the first to study the fine structure of the biological cellulose i.e. never-dried, native cellulose in a series of research work and articles (1)(2)(3)(4). They have shown that cellulose in the biological, native state is much more reactive than air-dried or conventional cellulose, and that in the biological state, cellulose fibers are as reactive as the never-dried regenerated cellulose. They also indicated that the reactivity of cellulose is correlated to the degree of dissociation of p 8 of 16 tp microfibrils to elementary fibrils or protofibrils of the magnitude 35 Å (3.5 nanometer) rather than to crystallinity (3).
Our recent work (10) on nanoadditives in papermaking, coupled with our interest in studying the fine structure of biological cellulose fibers, and keeping in view the possibility of commercial utilization of never dried cotton, all these facts led us to take the never dried biological cotton -as a new cellulose source-to patenting. In the present work we extended our studies and conducted several trials to preserve and protect the original nanostructure of the never-dried biological cotton fibers from cell wall collapse caused by nature air-drying. This is shown in the following section.

Vaccination of the Never-Dried Biological Cellulose Fibers (i.e. biological cotton staple fibers) with Glucose (the building unit of the cellulose molecule): -
The vaccination was performed in a 250 ml Conical flask with ground joint stopper. In each experiment, 4g of the never dried biological cotton staple fibers were put in the reaction vessel, and left for 1 hour in a sunny summer time at 35ºC. This was followed by addition of 100 ml of water containing the calculated amount of glucose (5,10,15 and 20% w/w).
The mixture was shaken by hand then left overnight at room temperature (30ºC). The vaccinated biological cotton staple fibers were then p 9 of 16 tp centrifuged under the same conditions used for determination of FSP (WRV). The centrifuged vaccinated never dried fibers were then air dried at room temperature. The produced nanocomposite was characterized for water uptake and density. Table 2 shows the results in case of using 20% w/w glucose for vaccination of the never-dried biological cellulose fibers (i.e. never-dried biological cotton staple fibers). It is obvious that vaccination of the neverdried biological cotton staple fibers with glucose, using our simple technique, protected the cell wall nanoporous structure against the attack of collapse due to drying. (Compare FSP values in Table2 and Table1).
Table3, also, illustrates the preservation and protection of the cell wall micropores or nanostructure against the irreversible collapse during drying. This is obvious by comparing the pore volume of the novel nanocomposite, produced after drying of the glucose vaccinated biological cellulose, versus the pore volume of cotton staple fibers dried without vaccination with glucose.
It is most probable that as the glucose-loaded cell wall dries, the glucose molecules prevent neighboring lamellae from collapse. These    Table 3 Relation between pore volume of air-dry fibers and fiber saturation point