Environmental Impact of Ether Carboxylic Derivative Surfactants

Emerging pollutants in textile wastewater: an ecotoxicological assessment focusing on surfactants

Water and several chemicals, including dyestuffs, surfactants, acids, and salts, are required during textile dyeing processes. Surfactants are harmful to the aquatic environment and induce several negative biological effects in exposed biota. In this context, the present study aimed to assess acute effects of five surfactants, comprising anionic and nonionic classes, and other auxiliary products used in fiber dyeing processes to aquatic organisms Vibrio fischeri (bacteria) and Daphnia similis (cladocerans). The toxicities of binary surfactant mixtures containing the anionic surfactant dodecylbenzene sulfonate + nonionic fatty alcohol ethoxylate and dodecylbenzene sulfonate + nonionic alkylene oxide were also evaluated. Nonionic surfactants were more toxic than anionic compounds for both organisms. Acute nonionic toxicity ranged from 1.3 mg/L (fatty alcohol ethoxylate surfactant) to 2.6 mg/L (ethoxylate surfactant) for V. fischeri and from 1.9 mg/L (alkylene oxide surfactant) to 12.5 mg/L (alkyl aryl ethoxylated and aromatic sulfonate surfactant) for D. similis, while the anionic dodecylbenzene sulfonate EC50s were determined as 66.2 mg/L and 19.7 mg/L, respectively. Both mixtures were very toxic for the exposed organisms: the EC50 average in the anionic + fatty alcohol ethoxylate mixture was of 1.0 mg/L ± 0.11 for V. fischeri and 4.09 mg/L ± 0.69 for D. similis. While the anionic + alkylene oxide mixture, EC50 of 3.34 mg/L for D. similis and 3.60 mg/L for V. fischeri. These toxicity data suggested that the concentration addition was the best model to explain the action that is more likely to occur for mixture for the dodecylbenzene sulfonate and alkylene oxide mixtures in both organisms. Our findings also suggest that textile wastewater surfactants may interact and produce different responses in aquatic organisms, such as synergism and antagonism. Ecotoxicological assays provide relevant information concerning hazardous pollutants, which may then be adequately treated and suitably managed to reduce toxic loads, associated to suitable management plans.

Complete biodegradability assessment of polyoxyethylene glycerol ester non-ionic surfactant: Aerobic, anaerobic, combined biodegradation and inhibitory effects

Aerobic and anaerobic biodegradability have become one of the most relevant characteristics for all contaminants. This is especially important in case of surfactants, which are discharged in wastewater treatment plants or directly into the aquatic bodies. The aim of this study is the integral assessment of the biodegradability of the non-ionic surfactant polyoxyethylene glycerol ester PGE-OE17. The aerobic and anaerobic biodegradation of PGE-OE17 was evaluated at different initial surfactant concentrations, and the evolution of the toxicity of the surfactant and its by-products was followed during the aerobic and anaerobic processes using bacteria Vibrio fischeri. PGE-OE17 was not completely biodegradable neither aerobically nor anaerobically, and the increase in the initial surfactant concentration had a negative effect in the biodegradation. Toxicity of the surfactant solutions and degradation by-products had a first increase followed by a gradual decrease during both tests, revealing that toxic substances released can harm the microorganisms and therefore hinder the biodegradation. Additionally, combined aerobic-anaerobic biodegradation tests were performed, consisting in a first aerobic treatment of different duration and initial concentration, followed by a complete anaerobic treatment. Results showed that a balance between aerobic and anaerobic biodegradation duration can maximize the biodegradation rates in comparison with only aerobic or anaerobic tests.

Invasion potential of the aquarium pet snail Planorbella trivolvis in India: impact of certain abiotic and biotic factors

Planorbella trivolvis (ramshorn snail) is one of India's most extensively sold exotic aquarium pet snails. The unintentional or deliberate release of P. trivolvis may result in the colonisation and establishment as an invasive snail in freshwater ecosystems. However, the successful invasion of P. trivolvis will depend on several abiotic and biotic factors of the concerned freshwater ecosystem. We have assessed the possibility of overcoming the opposing factors in P. trivolvis invasion through laboratory-based experiments and examined the effects of household-derived pollutants on egg hatchability, adult survivability and fecundity, and temperature (15 to 35 °C) on growth, sexual maturity, and reproduction. Additionally, we have evaluated the potential of native predators as biotic resistance to invasion by prey-choice experiment. The results indicated that egg hatchability, adult survivability, and fecundity were reduced with increasing pollutant concentration. However, the same traits did not differ from a native freshwater snail, Indoplanorbis exustus. The fecundity of P. trivolvis increased with increasing body size, but no considerable differences at different temperature levels suggest a wide range of adaptation to temperature. Faster growth and the requirement of comparatively few days to attain sexual maturity were observed in the higher temperatures. The native predators, Glossiphonia weberi and Diplonychus rusticus, avoided P. trivolvis as prey over the alternative prey snails in most instances, suggesting the masking of biotic resistance against the colonisation. Our observations indicate that the chance dispersal of P. trivolvis from household or commercial aquaria may lead to a possible invasion of freshwater ecosystems under suitable conditions.

Antagonistic Toxic Effects of Surfactants Mixtures to Bacteria Pseudomonas putida and Marine Microalgae Phaeodactylum tricornutum

Surfactants can be found in an ever-widening variety of products and applications, in which the combination of several types of surfactants is used to reinforce their properties, looking for synergistic effects between them. After use, they tend to be discarded into wastewater, ending up in aquatic bodies with concerning harmful and toxic effects. The aim of this study is the toxicological assessment of three anionic surfactants (ether carboxylic derivative, EC) and three amphoteric surfactants (amine-oxide-based, AO), individually and in binary mixtures of them (1:1 w/w), to bacteria Pseudomonas putida and marine microalgae Phaeodactylum tricornutum. Critical Micelle Concentration (CMC) was determined to demonstrate the capacity to reduce surface tension and the toxicity of the surfactants and mixtures. Zeta potential (ζ-potential) and micelle diameter (MD) were also determined to confirm the formation of mixed surfactant micelles. The Model of Toxic Units (MTUs) was used to quantify the interactions of surfactants in binary mixtures and to predict if the concentration addition or response addition principle can be assumed for each mixture. The results showed a higher sensitivity of microalgae P. tricornutum to the surfactants tested and their mixtures than bacteria P. putida. Antagonism toxic effects have been detected in the mixture of EC + AO and in one binary mixture of different AOs; this is to say, the mixtures showed lower toxicity than expected.

Influence of Inorganic Salts and pH on Surface Activity of Biodegradable Amido Gemini Amine Oxide Surfactant

The present study was designed to provide information regarding the influences of pH and inorganic salts on the surface activity of the amido Gemini amine oxide surfactants, the formula of which was C _n H_{2 n +1}CONH(CH₂)₂N⁺O^-(CH₃)-(CH₂)₂-(CH₃)N⁺O^-(CH₂)₂NHCOC _n H_{2 n +1} (n=11, 13, 15, and 17). Their biodegradability was also investigated. The results showed that the critical micelle concentration (CMC) and the corresponding surface tension (γ_CMC) changed regularly with the increase of the mass concentration of NaCl and CaCl₂. The optimal CMC and γ_CMC can be obtained by adjusting the inorganic salt content. Besides, the CMC near the isoelectric point of the surfactant is higher than the CMC within the isoelectric point. Furthermore, the biodegradability test revealed that the prepared surfactants had good biodegradability which was above 96% after 7 days.

Combined effect of nanoscale zero-valent iron and linear alkylbenzene sulfonate (LAS) to the freshwater algae Scenedesmus obliquus

With wide use of nanoparticles, co-exposure of aquatic organisms to nanoparticles and organic pollutants often takes place in the environment. However, the combined effects are still rarely understood. In this study, in order to study the interaction and biological effects of nanoscale zero-valent iron (nZVI) and linear alkylbenzene sulfonate (LAS), which acts as a typical surfactant, the freshwater algae Scenedesmus obliquus was exposed to nZVI and LAS individually and in combination for 96 h. According to the inhibition rate of the algae, the toxic effects were investigated by dose-response analysis. Then the combined effect of nZVI and LAS was evaluated using three evaluation models including toxicity unit (TU), additional index (AI), and mixture toxicity index (MTI). The results showed that the 96 h IC₅₀ of nZVI and LAS to Scenedesmus obliquus was 2.464 mmol L^-1 and 0.332 mmol L^-1, respectively. When nZVI coexisted with LAS at toxic ratio 1:1, the 96 h IC₅₀ value was 1.658 mmol L^-1 (shown with nZVI), and the partly additive effect of nZVI mixed with LAS was confirmed. However, when the toxic ratio of nZVI:LAS was 4:1, it showed synergistic effect. In addition, when nZVI mixed with LAS at toxic ratio 1:4, the joint effect is antagonistic effect. In addition, the content of chorophyll in Scenedesmus obliquus, especially the content of chlorophyll a, was decreased with the increase of mixture dose. However, the protein levels did not show significant changes at different mixture doses.

Synthesis of novel oligomeric anionic alkyl glycosides using laccase/TEMPO oxidation and cyclodextrin glucanotransferase (CGTase)-catalyzed transglycosylation

Modification of alkyl glycosides, to alter their properties and widen the scope of potential applications, is of considerable interest. Here, we report the synthesis of new anionic alkyl glycosides with long carbohydrate chains, using two different approaches: laccase/2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation of a long-carbohydrate-chain alkyl glycoside and cyclodextrin glucanotransferase (CGTase)-catalyzed elongation of anionic alkyl glycosides. The laccase/TEMPO oxidation of dodecyl β- d-maltooctaoside proceeded efficiently with the formation of aldehyde and acid products. However, depolymerization occurred to a large extent, limiting the product yield and purity. On the other hand, CGTase-catalyzed coupling/disproportionation reactions with α-cyclodextrin and dodecyl β- d-maltoside diuronic acid (DDM-2COOH) or octyl β- d-glucuronic acid (OG-COOH) as substrates gave high conversions, especially when the CGTase Toruzyme was used. It was found that pH had a strong influence on both the enzyme activity and the acceptor specificity. With non-ionic substrates (dodecyl β- d-maltoside and octyl β- d-glucoside), Toruzyme exhibited high catalytic activity at pH 5-6, but for the acidic substrates (DDM-2COOH and OG-COOH) the activity was highest at pH 4. This is most likely due to the enzyme favoring the protonated forms of DDM-2COOH and OG-COOH, which exist at lower pH (pKa about 3).

Ecotoxicity and interacting mechanism of anionic surfactant sodium dodecyl sulfate (SDS) and its mixtures with nonionic surfactant fatty alcohol-polyoxyethlene ether (AEO)

This paper reports the proportion-dependent toxicity of binary surfactant mixtures containing anionic sodium dodecyl sulfate (SDS) and nonionic fatty alcohol-polyoxyethlene ether (AEO) toward Photobacterium phosphoreum. The crucial role of toxicity interactions was elucidated by spectroscopic probing the refolding of the unfolded bovine serum albumin (BSA) induced by SDS and theoretical calculating the interaction parameter of mixed surfactants based on Rubingh's model from the critical micelle concentrations. The SDS/AEO mixtures can be divided into two groups based on the toxicity response to the proportion of AEO in the mixtures: Group I contained low mass proportions of AEO, that is, SDS:AEO = 4:1, 3:1; Group II featured high AEO proportions, that is, SDS:AEO = 3:2, 1:1, 2:3, 1:4. The toxicity of SDS/AEO mixtures decreased with the enhanced proportion of AEO in Group I and then fluctuated slightly when the AEO proportion increased to that of Group II. The mixture with the mass ratio of 1:1 showed a slightly higher toxicity than the others in Group II. Scanning electron microscopy (SEM) images illustrated that the addition of AEO hindered the action of SDS against the cell membrane. Fluorescence measurement indicated that AEO could extract SDS molecules embedded in the BSA matrix, except for those bound to the highly active sites of BSA, and refold stepwise the unfolded protein. The results were in excellent analogy to the proportion-dependent toxicity of SDS/AEO mixture, indicating the formation of mixed micelles playing a key role. The interaction parameter further revealed that antagonism led to the mixture with equal mass ratio (1:1) showing higher toxicity than other mass ratios in Group II. These results can be useful for compounding SDS/AEO mixtures in application efficiently and eco-friendly.

Ecotoxicity and micellization behavior of anionic surfactant sodium dodecylbenzene sulfonate (SDBS) and its mixtures with nonionic surfactant fatty alcohol-polyoxyethylene ether (AEO)

Surfactant mixtures have extensive industrial applications due to their ideal properties and low ecotoxicity. However, the ecotoxicity of surfactant mixtures with different proportions and their correlation with surface properties have remained poorly investigated. In this study, the ecotoxicity and surface activity of the composites of anionic surfactant sodium dodecylbenzene sulfonate (SDBS) and nonionic surfactant fatty alcohol-polyoxyethylene ether (AEO) in various mass ratios were assessed, and the correlation between ideal application properties and safe ecological perspective of the composites was explored. The ecotoxicity of individual SDBS, AEO, and SDBS/AEO mixtures was determined using the bioluminescence inhibition assay with Photobacterium phosphoreum, and the critical micelle concentrations (CMC) were measured by surface tension method and steady-state fluorescence spectroscopy. Sodium dodecylbenzene sulfonate (SDBS) showed a considerably higher toxicity than individual AEO and SDBS/AEO mixtures. Scanning electron microscope images illustrated the rupture of bacteria membrane induced by SDBS, and the addition of AEO alleviated the damage. According to the dose-response relationship on luminous bacteria, SDBS/AEO mixtures were divided into three groups (group I with a high proportion of SDBS, SDBS:AEO = 4:1 and 3:2; group II, SDBS:AEO = 1:1; group III with a high proportion of AEO, SDBS:AEO = 2:3 and 1:4). The sequence of toxicity of the SDBS/AEO mixtures was group II > group III > group I, demonstrating that the toxicity of the composites was related to the mixture proportion instead of the amount of AEO added. The CMC order of SDBS/AEO mixtures was group II > group I > group III, and it was proportion dependent. Furthermore, ΔC^M was defined as the difference of the experimental (C^M) and ideal CMC (C^Mi_deal) of the mixed system, indicating the interaction between the two kinds of surfactants. The order of the ΔC^M was group II > group III > group I, which was consistent with the sequence of the toxicity. Therefore, ΔC^M can be a potential indicator for the hazardous assessment of surfactant mixtures involving high ionic strength.

Aquatic toxicity and loss of linear alkylbenzenesulfonates alone and in a neonicotinoid insecticide formulation in surface water

Substance losses of linear alkylbenzene sulfonates (LASs) in a neat surfactant mixture, in an insecticide formulation Mospilan 20 SG, and in solutions with different neonicotinoid active ingredients (AIs) was studied in distilled water and in surface water samples originated from River Danube. Analytical measurements were performed both by HPLC-UV and commercial ELISA methods. Loss rates of LASs were found different in these aqueous matrices, with decomposition rates higher for the neat surfactant mixture than for Mospilan 20 SG (nearly 2- and 9-fold in distilled water and in surface water from River Danube, respectively). Half-lives determined in surface water from River Danube were shown to be affected by the presence of neonicotinoid AIs thiacloprid > imidacloprid > acetamiprid (ACE), while clothianidin and thiamethoxam did not affect LAS decomposition. Aquatic toxicity of Mospilan 20 SG, along with that of its AI ACE and co-formulant LAS, as well as the mixture of ACE and LAS was also investigated in the 48-h acute immobilisation assay on the water flea (Daphnia magna) aquatic indicator organism. LAS appeared to be significantly (8-fold) more toxic in the D. magna test than ACE, and the toxicity of the formulated insecticide was found to be 1.3 and 19.6 times higher than explained by its AI and LAS content, respectively, indicating synergistic toxicity. The strongest synergy between ACE and LASs was observed, when the neat forms of the two substances were applied in combination at concentrations equivalent to those in Mospilan 20 SG.

Silica micro- and nanoparticles reduce the toxicity of surfactant solutions

In this work, the toxicity of hydrophilic fumed silica micro- and nanoparticles of various sizes (7 nm, 12 nm, and 50 μm) was evaluated using the luminescent bacteria Vibrio fischeri. In addition, the toxicity of an anionic surfactant solution (ether carboxylic acid), a nonionic surfactant solution (alkyl polyglucoside), and a binary (1:1) mixture of these solutions all containing these silica particles was evaluated. Furthermore, this work discusses the adsorption of surfactants onto particle surfaces and evaluates the effects of silica particles on the surface tension and critical micellar concentration (CMC) of these anionic and nonionic surfactants. It was determined that silica particles can be considered as non-toxic and that silica particles reduce the toxicity of surfactant solutions. Nevertheless, the toxicity reduction depends on the ionic character of the surfactants. Differences can be explained by the different adsorption behavior of surfactants onto the particle surface, which is weaker for nonionic surfactants than for anionic surfactants. Regarding the effects on surface tension, it was found that silica particles increased the surface activity of anionic surfactants and considerably reduced their CMC, whereas in the case of nonionic surfactants, the effects were reversed.

Ecotoxicological characterization of polyoxyethylene glycerol ester non-ionic surfactants and their mixtures with anionic and non-ionic surfactants

This paper reports on a study that investigated the aquatic toxicity of new non-ionic surfactants derived from renewable raw materials, polyoxyethylene glycerol ester (PGE), and their binary mixtures with anionic and non-ionic surfactants. Toxicity of pure PGEs was determined using representative organisms from different trophic levels: luminescent bacteria (Vibrio fischeri), microalgae (Pseudokirchneriella subcapitata), and freshwater crustaceans (Daphnia magna). Relationships between toxicity and the structural parameters such as unit of ethylene oxide (EO) and hydrophilic-lipophilic balance (HLB) were evaluated. Critical micellar concentration (CMC) in the conditions of the toxicity test was also determined. It was found that the toxicity of the aqueous solutions of PGE decreased when the number of EO units in the molecule, HLB, and CMC increased. PGEs showed lower CMC in marine medium, and the toxicity to V. ficheri is lower when the CMC was higher. Given their non-polar nature, narcosis was expected to be the primary mode of toxic action of PGEs. For the mixture of surfactants, we observed that the mixtures with PGE that had the higher numbers of EO units were more toxic than the aqueous solutions of pure surfactants. Moreover, we found that concentration addition was the type of action more likely to occur for mixtures of PGE with lower numbers of EO units with non-ionic surfactants (alkylpolyglucoside and fatty alcohol ethoxylate), whereas for the mixture of PGE with lower EO units and anionic surfactant (ether carboxylic derivative), the most common response type was response addition. In case of mixtures involving amphoteric surfactants and PGEs with the higher numbers of EO units, no clear pattern with regard to the mixture toxicity response type could be observed.

Aerobic biodegradation of amphoteric amine-oxide-based surfactants: Effect of molecular structure, initial surfactant concentration and pH

The present study was designed to provide information regarding the effect of the molecular structure of amphoteric amine-oxide-based surfactants and the initial surfactant concentration on their ultimate biodegradation. Moreover, given this parameter's pH-dependence, the effect of pH was also investigated. Three amine-oxide-based surfactants with structural differences in their hydrophobic alkyl chain were tested: Lauramine oxide (AO-R₁₂), Myristamine oxide (AO-R₁₄) and Cocamidopropylamine oxide (AO-Cocoamido). We studied the ultimate biodegradation using the Modified OECD Screening Test at initial surfactant concentrations ranged from 5 to 75 mg L^-1 and at pH levels from 5 to 7.4. The results demonstrate that at pH 7.4, amine-oxide-based surfactants are readily biodegradable. In this study, we concluded that ω-oxidation can be assumed to be the main biodegradation pathway of amine-oxides and that differences in the biodegradability between them can be explained by the presence of an amide group in the alkyl chain of AO-Cocoamido; the CN fission of the amide group slows down their mineralization process. In addition, the increase in the concentration of the surfactant from 5 to 75 mg L^-1 resulted in an increase in the final biodegradation of AO-R₁₂ and AO-R₁₄. However, in the case of AO-Cocoamido, a clear relationship between the concentration and biodegradation cannot be stated. Conversely, the biodegradability of AO-R₁₂ and AO-R₁₄ was considerably lower in an acid condition than at a pH of 7.4, whereas AO-Cocoamido reached similar percentages in acid conditions and at a neutral pH. However, microorganisms required more time to acclimate.

Comprehensive review of several surfactants in marine environments: Fate and ecotoxicity

Surfactants are a commercially important group of chemicals widely used on a global scale. Despite high removal efficiencies during wastewater treatment, their high consumption volumes mean that a certain fraction will always enter aquatic ecosystems, with marine environments being the ultimate sites of deposition. Consequently, surfactants have been detected within marine waters and sediments. However, aquatic environmental studies have mostly focused on the freshwater environment, and marine studies are considerably underrepresented by comparison. The present review aims to provide a summary of current marine environmental fate (monitoring, biodegradation, and bioconcentration) and effects data of 5 key surfactant groups: linear alkylbenzene sulfonates, alcohol ethoxysulfates, alkyl sulfates, alcohol ethoxylates, and ditallow dimethyl ammonium chloride. Monitoring data are currently limited, especially for alcohol ethoxysulfates and alkyl sulfates. Biodegradation was shown to be considerably slower under marine conditions, whereas ecotoxicity studies suggest that marine species are approximately equally as sensitive to these surfactants as freshwater species. Marine bioconcentration studies are almost nonexistent. Current gaps within the literature are presented, thereby highlighting research areas where additional marine studies should focus.

Acute toxicity of anionic and non-ionic surfactants to aquatic organisms

The environmental risk of surfactants requires toxicity measurements. As different test organisms have different sensitivity to the toxics, it is necessary to establish the most appropriate organism to classify the surfactant as very toxic, toxic, harmful or safe, in order to establish the maximum permissible concentrations in aquatic ecosystems. We have determined the toxicity values of various anionic surfactants ether carboxylic derivatives using four test organisms: the freshwater crustacean Daphnia magna, the luminescent bacterium Vibrio fischeri, the microalgae Selenastrum capricornutum (freshwater algae) and Phaeodactylum tricornutum (seawater algae). In addition, in order to compare and classify the different families of surfactants, we have included a compilation of toxicity data of surfactants collected from literature. The results indicated that V. fischeri was more sensitive to the toxic effects of the surfactants than was D. magna or the microalgae, which was the least sensitive. This result shows that the most suitable toxicity assay for surfactants may be the one using V. fischeri. The toxicity data revealed considerable variation in toxicity responses with the structure of the surfactants regardless of the species tested. The toxicity data have been related to the structure of the surfactants, giving a mathematical relationship that helps to predict the toxic potential of a surfactant from its structure. Model-predicted toxicity agreed well with toxicity values reported in the literature for several surfactants previously studied. Predictive models of toxicity is a handy tool for providing a risk assessment that can be useful to establish the toxicity range for each surfactant and the different test organisms in order to select efficient surfactants with a lower impact on the aquatic environment.

Toward bioderived intelligent nanocarriers for controlled pollutant recovery and pH-sensitive binding

The pH-triggered formation of supramolecular complexes between the cationic biopolysaccharide chitosan and an environmentally friendly anionic surfactant is exploited for the formulation of selective and controlled-recovery systems. A strong advantage of this system is the very small pH range in which the binding/release process takes place. Because of this high pH responsiveness, chitosan-surfactant complexes are employed for the sequestration of various compounds by binding or releasing them from the complexes. In particular, the selective recovery of a model hydrophobic pollutant in the presence of a hydrophilic one is presented. The process is highly selective and effective, with more than 90% of the hydrophobic dye and ca. 10% of the hydrophilic dye recovered. Furthermore, the method can be extended to the selective recovery of metal ions, and in both cases, the original surfactant and chitosan mixture can be recovered, thereby rendering this an efficient and sustainable process. These showcase experiments depict quite different scenarios in which pH-responsive fully biodegradable polysaccharide-surfactant complexes can be employed and may substitute synthetic products in various fields, e.g., wastewater treatment, cosmetics, and agriculture, thereby yielding environmentally improved approaches.

From crab shells to smart systems: chitosan-alkylethoxy carboxylate complexes

In this work, self-assembly of alkyl ethylene oxide carboxylates and the biopolymer chitosan into supramolecular structures with various shapes is presented. Our investigations were done at pH 4.0, where the chitosan is almost fully charged and the surfactants are partially deprotonated. By changing the alkyl chain length and the number of ethylenoxide units very different water-soluble complexes can be obtained, ranging from globular micelles incorporated in a chitosan network to formation of ordered multiwalled vesicles. The structural characteristics of these complexes can be finely controlled by the mixing ratio of chitosan and surfactant, i.e., simply by the solutions composition. For instance, the vesicle wall thickness can be varied between 5 and 50 nm just by varying the mixing ratio. Accordingly, we expect this system to be an outstanding carrier for hydrophilic compounds with tunable release time option. Moreover, an easy route for preparation of chitosan-based complexes in the solid state with controlled mesoscopic order is presented. This work opens the way to prepare biofriendly materials on the basis of chitosan and mild anionic surfactants which are rather versatile with respect to their structure and properties, allowing for preparation of complexes with highly variable structures in both aqueous and solid phase. Formation of such different structures can be exploited for preparation of carriers, which are able to transport hydrophilic as well as hydrophobic molecules. Furthermore, as chitosan is well known to exhibit antibacterial and anti-inflammatory properties, different applications of these complexes can be indicated, i.e., as drug delivery systems or as coatings for medical implants.