Introduction

Bacteria are single-celled microorganisms that exist in a variety of environments and can have both positive and negative effects on human health and society. While some bacteria are beneficial and necessary for the human body's functioning, others can cause serious infections and diseases. (Altveş et al. 2020) The actual problem with bacteria is the increasing prevalence of antibiotic resistance, which means that certain strains of bacteria have evolved to become resistant to the antibiotics commonly used to treat infections. Antibiotic-resistant bacteria can cause a range of infections, from relatively minor conditions like urinary tract infections and skin infections to more serious illnesses like pneumonia and sepsis increasing also the risk of death. This problem can lead to longer-lasting illnesses and hospital stays, which can result in higher healthcare costs for patients and healthcare systems (Church and McKillip 2021). Different approaches have been applied, for instance the use of antibiotics is key to fight this problem. Their mechanisms involve: (1) damaging the cell wall and membrane, (2) altering the synthesis and structure of proteins and enzymes, and even (3) affecting nucleic acid synthesis. However, microorganism develop resistant by (1) inactivation of the antibiotic by degrading it through enzymes produced by the bacteria. (2) mutation/protection of the antibiotic's target, and (3) reduction of cell wall permeability, preventing the accumulation of the antibiotic inside the cell (Blair et al. 2015). Another approach to fight against this problem consisted in the incorporation of active nanoparticles into inactive polymeric matrix. For instance, oxides such as titanium dioxide and zinc oxide, among others, have been incorporated as inorganic antimicrobial fillers. These particles produced reactive oxygen species (ROS) that induced oxidative stress in the bacteria (Li et al. 2012). The drawback of this approach is the potential of the microorganism to become resistant, as it occurred with antibiotics.

One of the strategies being investigated to solve the problem of microorganisms' resistance to antibiotics is the development of polymers with inherent antimicrobial polymers. (Muñoz-Bonilla and Fernández-García 2012)(Jain et al. 2014) Among the different types, cationic polymers are the ones generating the most interest in recent years. The mode of action of cationic polymers is associated with their dual cationic and amphiphilic nature as a key role to interact, on one hand, with the negative net charge present in the bacterial cell envelope and, on the other hand, with the hydrophobic interior of the bacterial membrane, leading to a mechanism of cellular disruption that ultimately results in cell death (Muñoz-Bonilla and Fernández-García 2012; Yang et al. 2017).

Antimicrobial cationic polymers have a wide range of biomedical applications such as prostheses, stents, sutures, masks, skin wound dressings, and they are also used for food packaging, wearables, textiles, etc. (Škrlová et al. 2019; Umair et al. 2015; Wang et al. 2023; Hooshmand et al. 2022; Cheng et al. 2022; Chiloeches et al. 2022; Cottet et al. 2021)(Sun et al. 2023). Many of the applications are of a single use -disposable- (dressings, masks, protective textiles, food packaging…), therefore, it is necessary for these materials to be biodegradable in order to avoid the environmental impact they may cause. This fact, together with the pressing need to decrease the dependence on non-biodegradable synthetic polymers derived from fossil fuels resources has driven the growing interest on the use of natural and biobased polymers for the development of antimicrobial polymers.

In this context polysaccharides such as chitosan and cellulose are promising alternatives, being biocompatible and biodegradable, can be used in diverse applications as the mentioned before. In the case of chitosan, this natural polymer has antimicrobial character provided by the presence of amino groups. This amino groups are positively charged, and therefore with antimicrobial activity, in aqueous media at pH values below 6.5. (Rabea et al. 2003) In order to enhance the antimicrobial character of chitosan to physiological conditions, modification and quaternization of the amine group is probably the strategy that has been used the most. In this way permanent positive charges are formed (Oyervides-Muñoz et al. 2017; Phuangkaew et al. 2022; Muñoz-Nuñez et al. 2023).

When it comes to cellulose, this natural polymer as chitosan is a promising alternative to synthetic polymers. Being biodegradable, at the end of the life-cycle, it can be recycled minimizing the damage to the environment. Besides, cellulose is all around us: it is the most abundant natural polymer, the structural component of plant cell walls and represents one of the most important natural resources. (Yang et al. 2017) However, cellulose lacks of inherent antimicrobial activity. To overcome this limitation, researchers have explored various approaches to provide cellulose with antimicrobial property. (Muñoz-Bonilla et al. 2019) For instance, antimicrobial organic compounds such as essential oils have been mixed with to cellulose-based matrices, which are sometimes connected to the usage of stabilizer or interfacial agents. (Espitia et al. 2011; Casalini and Giacinti Baschetti 2023; Liakos et al. 2015, 2017) Yet, this approach can result in the migration of the molecule itself or stabilizing agent used to protect and keep the essential oil within the matrix. This migration cause damage to the environment or human health. (Chen et al. 2015) The incorporation of antimicrobial metal or metal-oxide nanoparticles (NPs), including Ag, Au, Cu, ZnO, and TiO2 NPs into cellulose matrix have also been explored (Malis et al. 2019). Among all, silver nanoparticles (AgNP) have attracted much attention due to their potent and broad inhibitory activity against a variety of antibiotic-resistant bacteria and other microorganisms (Gautam et al. 2021)(Mukha et al. 2013). Despite their effectiveness, research has shown that the unique properties that make AgNPs desirable for nanotechnology applications, such as their small size, large surface area, and chemical composition, can be harmful to the human body. Specifically, their nanometric size may enable them to cross biological barriers and penetrate delicate organs, including the cranioencephalic barrier (Costa et al. 2010; Teleanu et al. 2018). Besides, it has been also reported the presence of resistant bacteria to these metals (Teleanu et al. 2018).

In order to provide intrinsic antimicrobial activity to cellulose the followed strategies consisted in the chemical modification/functionalization to covalently attach polymers, peptides or moieties with antimicrobial character(Nie et al. 2021; Shahbazi et al. 2021; He et al. 2021; Sperandeo et al. 2020). For instance, in a recent study Sperandeo et al. have functionalized microcrystalline cellulose with two antimicrobial peptides with strong activity at very low concentrations against Gram-positive and Gram-negative bacteria. Such antimicrobial activity was also maintained in the cellulose-peptide polymer (Sperandeo et al. 2020). There are also examples of cellulose based polymers modified with Epsilon-poly-L-lysine (EPL), which is a cationic polypeptide produced by industrial fermentation and a proven broad spectrum antimicrobial agent (Nie et al. 2021; Shahbazi et al. 2021; He et al. 2021). He et al. (2021) prepared a series of dialdehyde microcrystalline cellulose crosslinked with EPL, which showed broad-spectrum antibacterial activity. The obtained materials were proposed as novel antimicrobial packaging bio-material. But considering that cellulose has the advantage of being cost-effective, in addition to the aforementioned benefits, then the use of peptides and EPL to modify cellulose will derive in an expensive product. An alternative approach involves covalently modifying cellulose with antimicrobial moieties such as N-halamines (Kong et al. 2019; An et al. 2023; Littunen et al. 2016), aminoalkyl groups (Roy et al. 2008; Do et al. 2023) and quaternary ammonium salts (QUAS) (Fei et al. 2018; Nemeş et al. 2022; Littunen et al. 2016). Specifically, the inspiration for modifying cellulose with cationic moieties comes from the successful performance of antimicrobial cationic polymers mentioned previously.

In this study, we report the chemical modification of microcrystalline cellulose with 1-methylimidazole to provide cellulose with antimicrobial properties. Imidazole heterocycle is widespread in nature, and its functional importance is vital in numerous structures within the human body, particularly as histamine and histidine, and DNA-based structures (Verma et al. 2013). In the literature, various biological activities have been reported for imidazole derivatives, including antibacterial, antitumor, antihypertensive and antioxidant, among others (Siwach and Verma 2021; Anderson and Long 2010). In this work, the modification process involved the covalent bonding of 1-methylimidazolium chloride to the cellulose structure. The resulting cationic polymer possessed both a positively charged group and a nonpolar alkyl chain, crucial for conferring antimicrobial activity and accomplish the mechanism of action described above for cationic polymers. The obtained cationic cellulose antimicrobial activity was assessed against both Gram-positive and Gram-negative bacteria.

Experimental part

Materials

Purified microcrystalline cellulose Avicel® PH-101 (MCC) was purchased from Sigma-Aldrich (Madrid, Spain). For the modification of MCC, N,N-dimethylformamide (DMF), thionyl chloride and 1-methylimidazole were obtained from Sigma-Aldrich (Madrid, Spain); and ammonium hydroxide was procured from PanReac. All chemicals employed were of analytical reagent grade. For the antimicrobial assay, Columbia agar (5% sheep blood) plates were obtained from BioMérieux. American Type Culture Collection (ATCC): Pseudomonas aeruginosa (P. aeruginosa, ATCC 27853) and Staphylococcus epidermidis (S. epidermidis, ATCC 12228) were purchased from Oxoid.

Preparation of 6-chloro-6-deoxycellulose (Cl-Cel) (Scheme 1)

Scheme 1
scheme 1

Schematic representation of the protocol for the preparation of 6-chloro-6-deoxycellulose from MCC

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Microcrystalline cellulose (MCC) (1 g, 6.10–4 mol, 1 Equiv.) was stirred in 20 mL of DMF for 20 min at 75 °C. Then, thionyl chloride (3.5 mL, 4.8 × 10–2 mol, 8 equiv.) was added to the suspension in a dropwise manner and the reaction was continued for 3 h at 85 °C under magnetic stirring. The product was precipitated in cold water. The dispersion was filtered and cleaned with ammonium hydroxide to neutralize the acid medium and with water until the pH was neutral. The final product was dialyzed for 5 days and lyophilized (Chen et al. 2015).

Preparation of cellulose anchored 1-methylimidazolium chloride (MIm-Cel) (Scheme 2)

Scheme 2
scheme 2

Procedure followed for the obtention of cationic cellulose MIm-Cel

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Briefly, 0.5 g of Cl-Cel was reacted with 5 mL of 1-methylimidazole (MIm) for 24 h at 95 °C under magnetic stirring. The suspension was precipitated in cold methanol and thoroughly cleaned with methanol. It was dried in vacuum at 45 °C, dialyzed for 48 h and finally dried in vacuum again at 45 °C (Chen et al. 2015).

Characterization

Solid state magnetic resonance (NMR) spectroscopy

In order to assess the success of the modification, solid-state 13C-NMR spectra for all synthesized compounds were performed on an Avance™ 400WB Bruker instrument with a wide-mouth superconducting magnet (89 mm) operating at 9.4 T with a 400.14 MHz. The conditions used to obtain the spectra: temperature of 296.5 K, acquisition time 0.05 s, 2000 scans and a frequency of 100 MHz.

Infrared spectroscopy

Similarly, Fourier Transform Infrared spectra (FT-IR) were recorded to qualitatively confirm the success of the modification. For that a Perkin Elmer Spectrum Two instrument between 400 and 4000 cm−1 spectral range with a 4 cm−1 resolution was used. The samples were prepared by grinding dried MCC, Cl-Cel and MIm-Cel (1 wt%) with potassium bromide (KBr) and pressing the mixture into transparent pellets. The spectra were acquired in transmission mode. A background spectrum was acquired before every sample and all samples were vacuum-dried prior to measurement.

Elemental analysis

In order to determine the degree of substitution achieved with the modifications, the elemental analysis of C, H, N and S was determined with a LECO CNHS932 elemental microanalyzer.

X-ray diffraction

The effect of cellulose modification in the crystallinity was studied through X-ray diffraction measurements performed on a Bruker D8 Advance diffractometer (XRD). The measurements were carried out using Cu Kα radiation (λ = 1.54 Å) in the range of 2θ = 4°–60° with a 2θ step of 0.024° and 0.5 s per step.

Thermo-gravimetric analysis

To evaluate the thermal stability, thermogravimetric analysis (TGA) was performed on a TA Instruments (TGA Q500, TA instruments) at a heating rate of 10 °C/min from 25 to 800 °C, under nitrogen atmosphere.

ζ potential measurements

The presence of positive charges in the samples was verified with ζ potential measurements. The ζ potential of the samples were measured in a diluted suspension in water (0.01 wt%) at 25 °C and physiological pH using a Zetasizer Nano series ZS (Malvern Instruments Ltd) using the Smoluchowski equation for electrophoretic mobility. The results are presented as the average of five measurements.

Antibacterial assays

The antimicrobial activity of all the samples was determined following the E2149-13a standard method of the American Society for Testing and Materials (ASTM) [15] against S. epidermidis and P. aeruginosa bacteria. In a first step, bacterial cells were incubated on 5% sheep blood Columbia agar plates for 24 h at 37 °C. Next, bacteria cultures were diluted in sterile saline solution to a concentration of 108 CFU/mL using the McFarland turbidity standard (0.5 McFarland) determined by a DEN-1 McFarland Densitometer (Biosan). These solutions were further diluted (1:200) with PBS to obtain ~ 106 CFU/mL. Then, 10 mg of the cationic cellulose were placed in a sterile falcon tube, where 1 mL of the tested bacterial suspension and 9 mL of PBS were added to reach a working bacteria solution of ~ 105 CFU/mL. Control experiments were performed on MCC and Cl-Cel, as well as experiments in the absence of any material. Then, suspensions were shaken at 120 rpm for 24 h at 37 °C. Further, tenfold serial dilutions and 1 mL of each was spread into sheep blood agar plates and incubated for 24 h at 37 °C. The bacterial count in each sample was assessed using the plate counting technique, and the percentage of cell killing was determined by comparing the number of colony-forming units (CFUs) observed with the control. These measurements were performed at least three times to ensure accuracy.

Results and discussion

Chemical modification of cellulose anchored with 1-methylimidazolium chloride (MIm-Cel).

The modifications of MCC into Cl-Cel and cellulose anchored 1- methylimidazolium chloride were confirmed using FTIR and solid state 13C-NMR. The infrared spectra of the MCC and its posterior modifications, Cl-Cel and MIm-Cel, are shown in Fig. 1. As it has been extensively reported, the bands corresponding to the cellulose backbone appear at 3370 cm−1, 2900 cm−1 and 1200–1000 cm−1 region attributed to the stretching vibration of OH groups, the stretching and deformation vibration of C–H groups in the glucose units and the stretching bands of the CO groups, respectively. In addition to this, in the region between 1500 and 1250 cm−1 several bands can be observed, which are also attributed to the deformation of the primary and secondary OH groups as reported in the literature (Silva Filho et al. 2013; Coseri et al. 2015).

Fig. 1
figure 1

FTIR spectra of MCC, Cl-Cel and MIm-Cel

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The chlorinated cellulose showed the appearance of two new bands at 750 and 725 cm−1, which correspond to the stretching vibration of the C–Cl bond (Silva Filho et al. 2013), as well as a new band at 1729 cm−1, which could be associated to the bending vibration of the C–Cl bond (Liu et al. 2023). Furthermore, the bands between 1500 and 1250 cm−1 have decreased intensity due to the substitution of the hydroxyl group on C6 (Silva Filho et al. 2013).

All these modifications have almost disappeared in the cellulose with methyl-imidazole, suggesting that the further modification has occurred but not entirely. Furthermore, new bands are observed in this polymer at 3159 cm−1, corresponding to the N–H stretching vibration and at 1570 cm−1, which can be attributed to the bending vibration of N–H and the stretching vibration of C–N. (Chen et al. 2015).

The modifications of MCC into Cl-Cel and cellulose anchored 1- methylimidazolium chloride were also confirmed using solid state 13C-NMR (Fig. 2), as mentioned. Since cellulose as well as modified cellulose were not soluble or stable enough in normal deuterated solvents or their mixtures, liquid-state NMR could not be performed. The spectrum of MCC describes the characteristic peaks for a polysaccharide made of glucose monomers covalently joined by β-1,4- glycosidic bonds. From left to right, the peak at 105.3 ppm is assigned to carbon C1 since it is bonded to two oxygen atoms. Following this peak, the peak at 89.3 ppm is assigned to carbon C4 since it is bonded to just one oxygen atom being responsible for the mentioned glycosidic bond. The high-intensity peaks at 75.2 and 72.5 ppm can be assigned to carbons C2, C3 and C5 since they are all secondary carbons and thus are bonded to two carbon atoms and a hydroxyl group each. Finally, the peak found at 65.2 ppm is assigned to carbon C6, being this one a primary carbon and thus only bonded to one carbon atom and a hydroxyl group (Chen et al. 2015).

Fig. 2
figure 2

Solid state 13C NMR spectra of MCC, Cl-Cel and MIm-Cel

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The successful modification of cellulose into 6-chloro-6-deoxycellulose (Cl-Cel) is explained by a very significant chemical shift of the peak associated to C6 carbon from 65.2 to 44.9 ppm, while peaks associated to C2, C3, C5 did not show any significant chemical shift. Nevertheless, a lower-intensity peak at 65.5 ppm is also detected, which might indicate that the modification has occurred but not completely. This peak could be associated to C6 carbon partially bonded to a hydroxyl group (da Silva Filho et al. 2006).

With the further modification of the structure, new peaks appear in the MIm-Cel spectrum, corresponding to the new moiety covalently attached, 1-methylimidazole. These new peaks were found at 138.6, 125.2, and 36.9 ppm and each of them are assigned respectively to C7, C8 and C9 and C10 of the new structure. On the other hand, C6″ is shifted with respect to C6′. However, based on the low intensity of this new peak, it is difficult to say whether there is still a C6′ region in the new spectra or the modification has been completely produced. Nevertheless, literature has described the presence of two peaks in this region, corresponding to C6′ and C6″ (Chen et al. 2015). C1, C4, C2, C3, C5 and C6 have not undergone any significant shift when compared to Cl-Cel.

To determine the extent of the modification, the degree of substitution for MIm-Cel was calculated using two methods. The first one is calculated via C13-NMR spectra corresponding to MIm-Cel and following the Eq. (1) (Wu et al. 2018)

$$ {\text{DS}} = \frac{{{\text{integral}} \left( {C10} \right)}}{{3 \times {\text{ integral}} \left( {C1} \right)}} \times 100 \% $$

where DS is the degree of substitution, the integral C10 represents the amount of imidazole incorporated to the structure, while the C1 triple integral represents the total amount of hydroxyl groups. Based on this method there was obtained a degree of substitution of 15%. For the second method DS was calculated on the basis of the percentage of nitrogen estimated by elemental analysis (N = 2.7 ± 0.3% N) and the resulting DS was 17% ± 2 in which is in agreement with that obtained by means of C13-NMR calculation.

As expected from the qualitative analysis of Solid 13C NMR as well as FTIR the modification of cellulose with imidazolium functional group has occurred successfully but not entirely. Further characterization regarding the surface charge density of MIm-Cel is necessary in order to determine if the attained degree of substitution is sufficient to accomplish the objective of cellulose cationization. In this regard, the zeta potential of MCC, Cl-Cel and MIm-Cel were measured and revealed values of − 42.6 ± 0.1 mV, − 48.6 ± 0.1 mV and + 14.2 ± 0.1 mV for MCC, Cl-Cel and MIm-Cel, respectively. Thus, the presence of the imidazole in the structure increases the positive surface charge of the sample. Such significant change demonstrates the success of the modification and confirms that the attained degree of substitution is enough to obtain cationic cellulose.

Effect of modification in the morphology, crystalline and thermal properties.

To understand the effect of modification in the morphology of cellulose, SEM images of MCC, Cl-Cel and MIm-Cel were performed. As observed in Fig. 3 the modified cellulose—Cl-Cel and MIm-Cel—showed a more rough surface compared to MCC with a porous structure (Nazir and Iqbal 2020). This surface modification could help to increase the contact area with respect to the bacteria and contribute to improve the antimicrobial activity that will be further determined (Echeverria et al. 2020).

Fig. 3
figure 3

SEM images corresponding to a MCC, b Cl-Cel and c MIm-Cel

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After confirming the partial modification of MCC to MIm-Cel, its effect on the crystalline properties was evaluated. The X-ray diffraction pattern of cellulose, as shown on Fig. 4, presents 4 remarkable peaks at 2θ = 15.6°, 16.6°, 22.6° and 34.8°, corresponding to the crystalline planes (\(1\bar{1} {0} \)), (110), (200) and (004), respectively, associated to cellulose Iß structure (French 2014).

Fig. 4
figure 4

X-ray diffraction patterns for MCC, Cl-Cel and MIm-Cel

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In accordance with literature, the diffraction pattern of Cl-Cel shows, apart from the original peaks from cellulose, new peaks formed from a different crystalline structure at 2θ = 25.8°, 26.7° and 27.7°. These show a decrease in intensity but the peaks are sharper than that observed in cellulose. Consequently, they can be attributed to the formation of crystallites as a result of the interaction of the bonded chlorine atoms with hydrogen (Zugenmaier 2001; Da Silva Filho et al. 2010). As observed, Cl-Cel undergoes a significant decrease of crystallinity due to the substitution of OH by Cl that provokes the disruption of the inter- and intramolecular hydrogen bonds and, consequently, of the structure of cellulose (Da Silva Filho et al. 2010). In the same way, MIm-Cel diffractogram presents the similar peaks of cellulose but broader, suggesting that the amorphous region is also higher. Compared with similar functionalization found in the literature (Do et al. 2023), it is worth mentioning that although the decrease in crystallinity is noticeable, the diffractogram still reflects diffraction peaks corresponding mainly to cellulose I structure.

The thermal properties of the MCC and modified samples are also investigated using thermogravimetry as shown in Fig. 5 where the thermograms of MCC, Cl-Cel and MIm-Cel are depicted. The observed initial weight loss from 25 to 100 °C in all samples is due to water evaporation; the hydroxyl groups of the cellulose and its derivatives are bonded to the water molecules (Jankowska et al. 2018). For MCC there is only one mass loss in the range of 250–350 °C which is attributed to the degradation of cellulose, the breakage of glycosidic bonds and the appearance of by-product (levoglucosan) (da Silva Filho et al. 2006, 2010). Almost the total decomposition is achieved with a residue of 2.5%. In the case of Cl-Cel a mass loss is found in the 150–200 °C range attributed to the loss of hydrochloric acid, which also contributes to catalyzed the bulk oxidation, and to the condensation of the hydroxyl groups in C2 and C3 (Da Silva Filho et al. 2010). The final residue of the Cl-Cel sample is 18%, which is notably higher than that of MCC. This increase can be attributed to the acid-catalyzed condensation of the intermediate products. These products are unable to evaporated resulting in the formation of the residue (Shafizadeh et al. 1978). In the case of MIm-Cel sample, a mass loss is found at 210–275 °C, which is attributed to imidazolium group loss together with the condensation of the OH groups of C2 and C3 (Chen et al. 2015; Bernard et al. 2018). In the range of 275–350 °C the mass loss associated to the degradation of cellulose is also observed. For this sample the final residue is of 27%. Some authors have related this increase in residue formation to the fact that the addition of heteroatoms as N can lead to the formation of heat-resistant compounds (Do et al. 2023).

Fig. 5
figure 5

Comparison of thermograms and differential curves of MCC, Cl-Cel and MIm-Cel

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As expected from the literature, Cl-Cel and MIm-Cel show a lower degradation temperature than that of cellulose, being less stable in terms of thermal properties. This result could be related to the fact that crystalline region of cellulose was disrupted, as demonstrated by XRD analysis, giving rise to less stable structures.

Antimicrobial activity

After confirming the modification of commercial microcrystalline cellulose with imidazolium as active functional group, MIm-Cel, the next step consisted in the evaluation of the obtained cationic cellulose as antimicrobial agents. For that, the antimicrobial activity was tested against both Gram-positive and Gram-negative bacteria using a contact killing method described in the experimental section. The obtained results are displayed in Fig. 6. As expected, both MCC and Cl-Cel do not produce any significant reduction of Gram-positive S. epidermidis. In the case of Gram-negative P. aeruginosa the lack of activity is total. It is possible that microfibers of cellulose can act as knifes or produce oxidative stress as graphene or carbon nanotubes (Zou et al. 2016; Noronha et al. 2021), damaging the membrane producing the cellular lysis in Gram-positive bacteria because they present single membrane in contrast with Gram-negative bacteria that have double cell well. The modification of cellulose with the incorporation of imidazolium group, on the other hand, reduces the number of bacteria in > 99.99% in the case of S. epidermidis and 99.6% in the case of P. aeruginosa. Therefore, Gram-positive bacteria demonstrate a more favorable interaction with MIm-Cel compared to Gram-negative bacteria. This discrepancy arises from the Gram-negative bacteria's double membrane composed of a bilayer of phospholipids, which presents a greater challenge for the interaction between the antimicrobial cationic cellulose and the bacteria (Muñoz-Bonilla and Fernández-García 2012; Lienkamp et al. 2009).

Fig. 6
figure 6

Antimicrobial activity of MCC, Cl-Cel and MIm-Cel against Gram-positive S. epidermidis and Gram-negative P. aeruginosa bacteria

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Conclusions

In this work a successful modification of microcrystalline cellulose was achieved by incorporating an imidazolium moiety, which exhibited antimicrobial activity. Solid-state NMR and elemental analysis confirmed the modifications with a degree of 1-methylimidazole substitution of 17%. The thermal stability decreases with the modification while increases the carbonaceous residue. The surface charge also increases with the final modification. Lastly, the antimicrobial activity of the resulting cationic cellulose was evaluated, revealing a remarkable reduction of over 99.99% against S. epidermidis and 99.3% against P. aeruginosa. Consequently, the chemical modification of cellulose with imidazolium moieties presents an array of opportunities for the development of versatile antimicrobial cellulose materials. Imidazole derivatives exhibit a broad spectrum of biological activities, and their integration into cellulose enhances the antimicrobial capabilities of this abundant natural polymer. Furthermore, through the investigation of cellulose modification, our objective is to develop antimicrobial materials that are both efficient and affordable. These materials have the potential to play a significant role in addressing antibiotic resistance. Hence, this cationic cellulose exhibits promising potential as an antimicrobial additive for incorporation into a biobased polymer matrix, enabling its application in various biomedical applications and food packaging.