Multichain aggregates in dilute solutions of associating polyelectrolyte keeping a constant size at the increase in the chain length of individual macromolecules

Multichain aggregates together with individual macromolecules were detected by light scattering in dilute aqueous solutions of chitosan and of its hydrophobic derivatives bearing 4 mol % of n-dodecyl side groups. It was demonstrated that the size of aggregates and their aggregation numbers increase at the introduction of hydrophobic side groups into polymer chains. The key result concerns the effect of the chain length of individual macromolecules on the aggregation behavior. It was shown that for both unmodified and hydrophobically modified (HM) chitosan, the size of aggregates is independent of the length of single chains, which may result from the electrostatic nature of the stabilization of aggregates. At the same time, the number of macromolecules in one aggregate increases significantly with decreasing length of single chains to provide a sufficient number of associating groups to stabilize the aggregate. The analysis of the light scattering data together with TEM results suggests that the aggregates of chitosan and HM chitosan represent spherical hydrogel particles with denser core and looser shell covered with dangling chains.     

Interaction of chitosans and their N-acylated derivatives with lipopolysaccharide of gram-negative bacteria

The interactions of lipopolysaccharide (LPS) with the natural polycation chitosan and its derivatives--high molecular weight chitosans (80 kD) with different degree of acetylation, low molecular weight chitosan (15 kD), acylated oligochitosan (5.5 kD) and chitooligosaccharides (biose, triose, and tetraose)--were studied using ligand-enzyme solid-phase assay. The LPS-binding activity of chitosans (80 kD) decreased with increase in acetylation degree. Affinity of LPS interaction with chitosans increased after introduction of a fatty acid residue at the reducing end of chitosan. Activity of N-monoacylated chitooligosaccharides decreased in the order: oligochitosan --> tetra- > tri- --> disaccharides. The three-dimensional structures of complexes of R-LPS and chitosans with different degree of acetylation, chitooligosaccharides, and their N-monoacylated derivatives were generated by molecular modeling. The number of bonds stabilizing the complexes and the energy of LPS binding with chitosans decreased with increase in acetate group content in chitosans and resulted in changing of binding sites. It was shown that binding sites of chitooligosaccharides on R-LPS overlapped and chitooligosaccharide binding energies increased with increase in number of monosaccharide residues in chitosan molecules. The input of the hydrophobic fragment in complex formation energy is most prominent for complexes in water phase and is due to the hydrophobic interaction of chitooligosaccharide acyl fragment with fatty acid residues of LPS.     

Kinetics of ultrasonic degradation and polymerisation degree distribution of sonochemically degraded chitosans

The process of physical degradation by means of the ultrasonic action towards chitosans with mole fraction of 2-acetamido-2-deoxy-β- -glucopyranose units (the degree of N-acetylation, F_A) in the range of 0.10≤F_A≤0.28, and the weight average polymerisation degree in the range of has been investigated. The decrease of as well as changes in the distribution of the degree of polymerisation (P) has been determined as a function of time, F_A, temperature, concentration of chitosan solution and concentration of acetic acid in the solution. The use of low-power ultrasound emitter allowed to establish that in the case of chitosan (binary heteropolysaccharide) the general rate parameter (k) increased with F_A. This can be explained by the relatively stronger aggregation of macromolecules with higher F_A, which results in size increase of macromolecular individuals and hence in their higher susceptibility to ultrasonic action. It was also observed that k decreased with chitosan concentration and temperature. The value of limiting degree of polimerisation (x_e) was found to be influenced by structural parameters of chitosan chains (F_A, aggregation). The increase of acetic acid concentration caused the increase in the k value, what indicated accelerating effect of ultrasound towards acidic hydrolysis of chitosan. The shape of the P curve of sonochemically degraded chitosans are in good correlation with the mid-point breakage concept of degradation accepted in sonochemical degradation of polymers.     

Enzymatic hydrolysis of chitosan films in water and physiological solution

It was shown that the processes of enzymatic hydrolysis of chitosan in aqueous acetic acid and on the surface of chitosan films in a solution of hyaluronidase in acetic acid are described by uniform kinetic constants. Kinetic parameters of enzymatic hydrolysis of the chitosan film samples in water and in physiological solution (Ringer–Locke’s solution) were determined. It was found that the introduction of medicinal agents and low-molecular-weight electrolytes to a chitosan-based film material reduces the rate of enzymatic hydrolysis of the films, which may indicate a possible increase in their service life when used on the wound surface.     

Interaction of bacterial endotoxins with chitosan. Effect of endotoxin structure, chitosan molecular mass, and ionic strength of the solution on the formation of the complex

The interaction of endotoxins of different structure (lipopolysaccharides (LPS) and lipopolysaccharide-protein complexes (LPPC)) with chitosan has been studied. It was shown that the mechanism of interaction is rather complicated and depends on the macromolecular organization of endotoxin as well as on the degree of polymerization of the chitosan. Chitosan with molecular mass of 20 kD reveals higher affinity to LPS than chitosan with molecular mass of 140 kD. Endotoxins with long O-specific chains can bind completely with chitosan with the formation of LPS-chitosan and LPPC-chitosan complexes with weight ratios between the original components of 1:1 and 1:5. When endotoxins with higher degree of hydrophobicity and short O-specific chains were mixed with chitosan, a part of the LPS remained unbound. The stability of the complexes formed depends on ionic strength. It was shown that, in addition to electrostatic forces, other types of forces take part in the formation of the complexes. A decrease in acute toxicity of various LPSs is observed on their binding with chitosans.     

Ionization and solubility of chitosan solutions related to thermosensitive chitosan/glycerol-phosphate systems

Chitosan is a linear cationic biopolymer composed of glucosamine and N-acetyl-glucosamine that is only soluble in acidic aqueous solutions and precipitates when neutralized. However, it was recently discovered that chitosan dissolved in solutions containing glycerol phosphate was soluble at near neutral pH and produced a sol-gel transition when heated. Understanding this unique thermogelling system requires improved characterization of the ionization and solubility behaviors of chitosan, in particular dependencies on temperature, salt, chitosan concentration, and fD, where fD is the fraction of glucosamine monomers (deacetylated monomers) in chitosan. In the current study we performed temperature-controlled titration and dilution experiments on chitosan solutions with fD of 0.72, 0.85, and 0.98 at concentrations ranging from 1.875 to 30 mM of its glucosamine monomer and with 0 to 150 mM added salt. Light transmittance measurements were performed during titration to indicate precipitation. We found the apparent proton dissociation constant of chitosan, pKap, to (1) decrease strongly with increased temperature, (2) increase strongly with increased salt, (3) increase strongly with increased chitosan concentration in low-salt conditions, and (4) decrease weakly with increasing fD. All of the above influences on chitosan pKap were accurately predicted using a mean-field Poisson-Boltzmann (PB) cylindrical cell model where the only adjustable parameter was the temperature-dependent chitosan intrinsic monomeric dissociation constant pK0(T). The resulting chitosan pK0 values at 25 degrees C were in the range from 6.63 to 6.78 for all chitosans and salt contents tested. The temperature dependence of chitosan ionization was found to strongly reduce pK0(T) by 0.023 units per degrees C, for example, resulting in a reduction of chitosan pK0(T) from 7.1 at 5 degrees C to 6.35 at 37 degrees C for fD of 0.72 in 150 mM salt. A similar temperature-dependent reduction of the pKa of the glucosamine monomer was found (-0.027 units per degrees C) while the pKa of glycerol phosphate did not change significantly with temperature. The latter result suggested that chitosan solutions heated in the presence of glycerol phosphate will become partly neutralized by transferring protons to glycerol phosphate and thereby allow attractive interchain forces to form a physically cross-linked gel under the appropriate conditions. Additionally, the degree of ionization of chitosan when it precipitates upon addition of a strong base was measured to be in the range from 0.25 to 0.55 and was found to (1) be insensitive to temperature, (2) increase strongly with increased salt, and (3) increase strongly with fD. The salt effect was accounted for by the PB model, while the influence of fD appeared to be due to acetyl groups impeding attractive chain-to-chain association to increase solubility and require reduced ionization levels to precipitate.     

Interaction of N-acylated and N-alkylated chitosans included in liposomes with lipopolysaccharide of gram-negative bacteria

The interactions of lipopolysaccharide (LPS) with the polycation chitosan and its derivatives — high molecular weight chitosans (300 kDa) with different degree of N-alkylation, its quaternized derivatives, N-monoacylated low molecular weight chitosans (5.5 kDa) — entrapped in anionic liposomes were studied. It was found that the addition of chitosans changes the surface potential and size of negatively charged liposomes, the magnitudes of which depend on the chitosan concentration. Acylated low molecular weight chitosan interacts with liposomes most effectively. The binding of alkylated high molecular weight chitosan with liposomes increases with the degree of its alkylation. The analysis of interaction of LPS with chitoliposomes has shown that LPS-binding activity decreased in the following order: liposomes coated with a hydrophobic chitosan derivatives > coated with chitosan > free liposomes. Liposomes with N-acylated low molecular weight chitosan bind LPS more effectively than liposomes coated with N-alkylated high molecular weight chitosans. The increase in positive charge on the molecules of N-alkylated high molecular weight chitosans at the cost of quaternization does not lead to useful increase in efficiency of binding chitosan with LPS. It was found that increase in LPS concentration leads to a change in surface ζ-potential of liposomes, an increase in average hydrodynamic diameter, and polydispersity of liposomes coated with N-acylated low molecular weight chitosan. The affinity of the interaction of LPS with a liposomal form of N-acylated chitosan increases in comparison with free liposomes. Computer simulation showed that the modification of the lipid bilayer of liposomes with N-acylated low molecular weight chitosan increases the binding of lipopolysaccharide without an O-specific polysaccharide with liposomes due to the formation of additional hydrogen and ionic bonds between the molecules of chitosan and LPS.     

Effect of spatial architecture on cellular colonization

The spatial cell-material interaction remains vital issue in forming biodegradable scaffolds in Tissue Engineering. In this study, to understand the influence of spatial architecture on cellular behavior, 2D and 3D chitosan scaffolds of 50-190 kD and >310 kD MW were synthesized through air drying and controlled rate freezing/lypohilization technique, respectively. In addition, chitosan was emulsified with 19, 76, and 160 kD 50:50 poly lactide-co-glycolide (PLGA) using 1,2-Dimyristoyl-sn-Glycero-3-Phosphocholine (DMPC) as stabilizer. 2D and 3D scaffolds were formed by air drying and lyophilization as before. Tensile and compressive properties of films and scaffolds were analyzed in wet conditions at 37 degrees C. Alterations in the cell spreading, proliferation, and cytoskeletal organization of human umbilical vein endothelial cells (HUVECs) and mouse embryonic fibroblasts (MEFs) were studied. These results showed that the formed 3D chitosan scaffolds had interconnected open pore architecture (50-200 microm size). HUVECs and MEFs had reduced spreading areas and circular morphology on 2D chitosan membranes compared with 3D chitosan scaffolds. The fluorescence photomicrographs for actin (using Alexa Fluor 488 phalloidin) and cytoplasm staining (using carboxyfluorescein diacetate-succinimidyl ester) demonstrated that the cells spread within 3D chitosan matrix. 2D and 3D emulsified chitosan and chitosan/PLGA scaffolds reduced the spreading of HUVECs and MEFs even further. Proliferation results, analyzed via MTT-Formazan assay and BrdU uptake assay, correlated with the spreading characteristics. The reductions in cell spreading area on emulsified surfaces were not detrimental to the viability and endocytic activity but to proliferation. The observed alterations in cellular colonization are in part due to the substrate stiffness and surface topography. In summary, these results suggest a significant influence of spatial architecture on cellular colonization.     

Blending chitosan with polycaprolactone: effects on physicochemical and antibacterial properties

Chitosan is a well sought-after polysaccharide in biomedical applications and has been blended with various macromolecules to mitigate undesirable properties. However, the effects of blending on the unique antibacterial activity of chitosan as well as changes in fatigue and degradation properties are not well understood. The aim of this work was to evaluate the anti-bacterial properties and changes in physicochemical properties of chitosan upon blending with synthetic polyester poly(epsilon-caprolactone) (PCL). Chitosan and PCL were homogeneously dissolved in varying mass ratios in a unique 77% acetic acid in water mixture and processed into uniform membranes. When subjected to uniaxial cyclical loading in wet conditions, these membranes sustained 10 cycles of predetermined loads up to 1 MPa without break. Chitosan was anti-adhesive to Gram-positive Streptococcus mutans and Gram-negative Actinobacillus actinomycetemcomitans bacteria. Presence of PCL compromised the antibacterial property of chitosan. Four-week degradation studies in PBS/lysozyme at 37 degrees C showed initial weight loss due to chitosan after which no significant changes were observed. Molecular interactions between chitosan and PCL were investigated using Fourier transform infrared spectroscopy (FTIR) which showed no chemical bond formations in the prepared blends. Investigation by wide-angle X-ray diffraction (WAXD) indicated that the crystal structure of individual polymers was unchanged in the blends. Dynamic mechanical and thermal analysis (DMTA) indicated that the crystallinity of PCL was suppressed and its storage modulus increased with the addition of chitosan. Analysis of surface topography by atomic force microscopy (AFM) showed a significant increase in roughness of all blends relative to chitosan. Observed differences in biological and anti-bacterial properties of blends could be primarily attributed to surface topographical changes.     

Chitosan cross-linking with a water-soluble,blocked diisocyanate. 1. Solid state

The present investigation focuses on the synthesis and application of a cross-linking agent that is compatible with the solubility characteristics of chitosan. A water-soluble, blocked-diisocyanate was prepared as a bisulfite adduct to 1,6-hexamethylene diisocyanate, which proved to be stable for several weeks in aqueous, acidic chitosan solutions at room temperature. Thermal cross-linking of chitosan as cast, dried films was investigated by varying the NCO/NH(2) ratio from 0.0 to 1.2. Spectroscopic (IR), thermal (TGA), swelling, and structural (WAXD) studies indicated that chitosan was cross-linked in a concentration-dependent manner under mild thermal conditions: 60 degrees C for 24 h. Cross-linking inefficiency was concluded to be due to lack of mobility of the reacting species in the solid state. In a preliminary study, the enzymatic degradation with Chitinase (E. C. 3.2.1.14) from Streptomyces griseus was found to be the greatest for non-crosslinked chitosan, followed by chitin, and then by cross-linked samples.     

Investigation of mechanical properties,morphology, and biodegradability of compositions based on polylactide and polysaccharides

The blends of polylactide with ethyl cellulose and chitosan are obtained in a Brabender mixer under conditions of high temperature shear deformation at different initial ratios of the reagents. The investigation of physicomechanical properties of the compositions has shown that the systems have high rigidity. Polyethylene glycol (PEG) and high-molecular-weight polyolefin polydecene have been added to the compositions in order to improve their elasticity. It has turned out that polydecene scarcely affects the mechanical characteristics, while PEG leads to a noticeable increase in elongation at break. Biodegradability of the compositions is investigated by the mass loss of samples after holding in soil, fungus resistance tests, and the analysis of the film morphology by scanning electron microscopy after holding in soil. It is found that the introduction of the third component (PEG) leads to an increase in biodegradability of the compositions.     

Immobilization of catalase on chitosan film

Catalase was immobilized on the chitosan film that is a natural polymer. Studies were done on free catalase and immobilized catalase on chitosan film concerning the determination of optimum temperature, optimum pH, thermal stability, storage stability, operational stability, and kinetic parameters. It was determined that optimum temperature for free catalase and immobilized catalase on chitosan film is 25 degrees C, and optimum pH is 7.0. It was found as K(m) = 25.16 mM, V(max) = 24042 μmole/min mg protein for free catalase, K(m) = 27.67 mM, V(max) = 1022 μmole/min mg protein for immobilized catalase on chitosan. It was observed that there was a big difference between V(max) value of the free catalase and V(max) value of immobilized catalase on chitosan film whereas there were minor changes in the value of K(m) for free catalase and immobilized catalase. It was found that storage stability at 5 degrees C for immobilized catalase stored wet is greater than free catalase and immobilized catalase stored dry, and immobilized catalase showed a operational stability.     

Preparation and physicochemical properties of a novel hydroxyapatite/chitosan–silk fibroin composite

A novel hydroxyapatite/chitosan–silk fibroin (HA/CTS–SF) composite was prepared for bone repair and replacement by a coprecipitation method. It was revealed that the inorganic phase in the composite was carbonate-substituted HA with low crystallinity. The HA crystallites were found to be needle-like in shape with a typical size of 20–50 nm in length and around 10 nm in width. The composite exhibited a higher compressive strength than the precipitated HA without any organic source involved, which was closely related to the perfect incorporation of chitosan and SF macromolecules into the composite. The chemical interactions occurring between the mineral phase and the organic matrix were thought to improve the interfacial bonding and thus resulted in the enhanced mechanical property of the composite.     

铜绿假单胞菌NY3胞外分泌物对降解烃类的影响作用

为了研究铜绿假单胞菌Pseudomonas aeruginosa NY3胞外分泌物对烃类降解的作用,对胞外分泌物影响烃类降解的效率进行了研究。研究发现,NY3菌以LB培养基和以烃类为唯一碳源的无机盐培养基培养得到的种子液,离心并洗涤菌体后,菌细胞代谢烃类效率明显下降。分别利用盐析和溶剂萃取法,提取种子液上清液中胞外大分子和小分子,且投加在NY3菌(离心后的菌细胞)降解十四烷的无机盐培养基中,发现24 h内外加胞外大分子化合物,使NY3菌对十四烷去除率可提高约14%,而投加小分子化合物使NY3菌24 h内对十四烷去除率提高约6%。利用SDS-page聚丙烯酰氨凝胶电泳分离胞外大分子,结果发现主要是该菌胞外所分泌的蛋白或多肽类,主要有3个条带,它们的分子量约在35~55 k D范围内,其对烃降解促进作用机理有待进一步验证。利用飞行质谱(LCMS-IT-TOF)鉴定胞外小分子分泌物,结果表明在本研究条件下,它们均为氧化还原反应活性物,可以加快反应体系中电子传递速度,促进底物的氧化还原反应。     

Isolation and Properties of Major Components of Penicillium canescens Extracellular Enzyme Complex

The composition of the enzyme complex secreted by Penicillium canescens was investigated. A scheme for purification of the main components of the complex by chromatofocusing on a Mono P column was developed. It was found that along with beta-galactosidase, the major components of the complex were endo-beta-1,4-xylanase (31 kD, pI 8.2-9.3), alpha-L-arabinofuranosidase (60 kD, pI 7.6), arabinoxylan-arabinofuranohydrolase (70 kD, pI 3.8-4.0), and endo-beta-1,3/1,4-glucanase (40 kD, pI 4.4). The substrate specificity, pH and temperature activity optima, adsorbability, thermal stability, and ability for synergic interaction of the isolated enzymes were studied.     

HSP_(70)基因表达对高粱育性的影响(英文)

高粱细胞质雄性不育系３１９７Ａ（３Ａ）在常温条件下是不育的（Ｆｉｇｓ．１１＆２）,经热激（４５℃）诱导不同程度地恢复了育性（Ｆｉｇｓ．１３＆４）,为研究其不育机理提供了线索。热激２ｈ后,３Ａ中即可产生一类线粒体热激蛋白（ＨＳＰｓ）。其中,分子量为７０ｋＤ的ＨＳＰ７０含量最高,也最为稳定。不过,３Ａ中ＨＳＰｓ的稳定性弱于保持系３１９７Ｂ（３Ｂ）（Ｆｉｇ．２,Ｐａｎｅｌｓ１～４）。放线菌素Ｄ抑制ＨＳＰｓ的合成,而氯霉素无此作用（Ｆｉｇ．２,Ｐａｎｅｌｓ５＆６）,表明：ＨＳＰｓ是由核基因编码、在细胞质中合成、再跨膜转运到线粒体中的。３Ａ幼穗经热激后,线粒体的总蛋白量猛增了２．７倍（Ｆｉｇ．３）,达到３Ｂ的水平,育性亦变为可育的。Ｆｉｇ．４表明：ＨＳＰ７０反义链ｃＤＮＡ（Ｒ１）能进入到３Ｂ花药细胞中,并与靶ＲＮＡ（ＨＳＣ７０ｍＲＮＡ）结合,而对照、正义链ｃＤＮＡ（Ｄ）链无此反应。由此、再增加一个通用保守序列的反义链ｃＤＮＡ（Ｒ２）、共两个探针（Ｒ１、Ｒ２）,可以检测到：３Ａ在常温下没有能力合成ＨＳＣ７０ｍＲＮＡ（Ｆｉｇ．５）,而在热激条件下,转变为有能力（Ｆｉｇ．６）。启示：３Ａ在热激条件下由不育转变为可育     

Microwave-assisted degradation of chitosan for a possible use in inhibiting crop pathogenic fungi

Degradation of chitosan by H(2)O(2) under microwave irradiation was investigated. The oxidative degradation of chitosan was highly accelerated by microwave irradiation under the condition of low temperature and low concentration of H(2)O(2). The degraded chitosans with low molecular weight (M(w)) were characterized by gel permeation chromatography, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray diffraction and elemental analysis. The decrease of M(w) led to transformation of crystal structure and increase of water solubility, whereas no significant chemical structure change in the backbone of chitosan was observed. Antifungal activities of chitosans with different M(w) against crop pathogenic fungi Phomopsis asparagi, Fusarium oxysoporum f. sp. Vasinfectum and Stemphylium solani were investigated at the concentrations of 100, 200 and 400mg/L. All degraded chitosans with low M(w) exhibited enhanced antifungal activity compared with original chitosan and the chitosan of 41.2kDa showed the highest activity. At 400mg/L, the chitosan of 41.2kDa inhibited growth of P. asparagi at 89.3%, stronger than polyoxin and triadimefon, the inhibitory effects of which were found to be 55.5% and 68.5%. All the results indicated that oxidative degradation under microwave irradiation was a promising technique for large-scale production of low M(w) chitosan for use in crop protection.     

The properties of natural silk fibers: deformation study and NMR data

Natural silk (Bombyx mori) fibers with low humidity (0.07 g H2O/g dried silk) after temperature influence were studied for mechanical longitudinal deformation. On the basis of the stress-strain curves, some estimates of tensile properties for silk fibers were obtained. It was found that the maximal tension (sigma(max) in tensile-linear field of deformation of silk fibers decreases with increasing fiber diameter. The results showed that the heating of fibers (100 degrees C) results in a diminishing of the sigma(max)-value. Scanning electron microscopy pictures for cross section and longitudinal fiber surface were obtained. Natural silk fibers were studied by the NMR relaxation method (free induction decay curves) and the second moments of NMR-line shape in silk samples were calculated. The intra- and intermolecular contributions into the second moment were analyzed. The results showed a strong interaction of water molecules with macromolecules and a low molecular mobility. Some characteristics of interactions between silk macromolecules and water molecules as well as the role of intermolecular links in the change of the structure-function properties of natural silk under the action of external factors are discussed.     

纤维素酶中具有壳聚糖水解酶活性成分的鉴定

在壳聚糖酶的研究过程中,目前已发现37种酶具有非专一性地降解壳聚糖的能力[1].对这些非专一性酶水解壳聚糖的机理有两种看法:一些人认为,由于这些酶大都来自商业酶制剂,未经过进一步的纯化,故有人认为其中所含的少量杂质可能是产生水解活力的原因;但也有人认为,在所有的酶制剂中都存在同一种杂质似乎是不可能的,因为这些酶来源于广泛的微生物、真菌、哺乳动物和植物等.众所周知,酶具有高度的专一性,即对所催化的反应和底物有严格的选择性,一种酶往往只能催化一种或一类反应;有如此多的不同种类的酶能非专一性地水解壳聚糖.因而探讨具有水解…     

Study of the near-neutral pH-sensitivity of chitosan/gelatin hydrogels by turbidimetry and microcantilever deflection

The fundamental properties and pH-sensitivity of chitosan/gelating hydrogels were investigated using spectroscopic and microelectro mechanical (MEMS) measurement approaches. Turbidimetric titration revealed that there were electrostatic attractive interactions between tripolyphosphate (TPP), chitosan, and gelatin in the acidic pH range, depending on their degree of ionization. The pH-sensitive swelling behavior of the hydrogels was investigated by monitoring the deflection of hydrogel-coated microcantilevers, which exhibited a sensitive and repeatable response to solution pH. The deflection of the microcantilever increased as the pH decreased, and the response speed of the system exhibited a nearly linear relationship with pH. The effects of the pH and concentration of TPP solution, as well as the ratio of chitosan to gelatin in gel precursor solutions, on the pH sensitivity of the hydrogels were also investigated. It was found that the swelling of the hydrogel is mainly a result of chain relaxation of chitosan-TPP complexes caused by protonation of free amino groups in chitosan, which depends on the crosslinking density set during the formation of the network. An increase in initial crosslink density induced a decrease in swelling and pH sensitivity. It can be concluded from this study that pH-sensitive chitosan gel properties can be tuned by preparatory conditions and inclusion of gelatin. Furthermore, microcantilevers can be used as a platform for gaining increased understanding of environmentally sensitive polymers.