Histidine In Solution Research Articles

Synthesis and evaluation of a 99mTc tricarbonyl-labeled somatostatin receptor-targeting antagonist peptide for imaging of neuroendocrine tumors

IntroductionA somatostatin receptor (SSTR)-targeting antagonist peptide (sst2-ANT) was radiolabeled with 99mTc tricarbonyl via a tridentate [N,S,N]-type ligand (L) to develop a radiodiagnostic agent, 99mTcL-sst2-ANT, for imaging of SSTR-expressing neuroendocrine tumors. MethodsReceptor affinity was assessed in vitro with the nonradioactive analogue, ReL-sst2-ANT, via a challenge experiment in AR42J cells with 125I–SS-14 as the competing radioligand. Preparation of 99mTcL-sst2-ANT was achieved via reaction of [99mTc(CO)3(H2O)3]+ with L-sst2-ANT. To test the stability of the radiolabeled complex, challenge experiments were performed in phosphate-buffered saline solutions containing cysteine or histidine and also in mouse serum. Biodistribution and micro-SPECT/CT imaging studies were performed in AR42J tumor-bearing female ICR SCID mice. ResultsThe half maximal inhibitory concentration (IC50 value) of ReL-sst2-ANT in AR42J cells was 15nM. Preparation of 99mTcL-sst2-ANT was achieved with ≥97% radiochemical yield (RCY) and was verified by HPLC co-elution with the ReL-sst2-ANT analogue. The radiolabeled complex remained intact for up to 24h in high concentration solutions of cysteine and histidine at 37°C. Furthermore, the radiotracer was 90% stable for 1h at 37°C in mouse serum. Micro-SPECT/CT images showed clear uptake in tumors and were supported by the biodistribution data, in which the 3.2% ID/g tumor uptake at 4h was significantly blocked by co-administration of nonradioactive SS-14. ConclusionsA [99mTc(CO)3(N,S,N)]+ chelate was employed for radiolabeling of an SSTR-targeting antagonist peptide. Synthesis of 99mTcL-sst2-ANT was achieved in high RCY, and the resulting complex displayed high in vitro stability. Somatostatin receptor affinity was retained in both cells and in tumor-bearing mice, where the complex successfully targeted SSTR-positive tumors via a receptor-mediated process.Advances in Knowledge and Implications for Patient Care.This first 99mTc-tricarbonyl-labeled SSTR antagonist peptide showed promising in vivo tumor targeting in mice. Future studies may lead to translation of a similar design into the clinic.

Study to explore diverse interactions of amino acids and vitamin molecule in aqueous environment

ABSTRACTPhysico-chemical study of solute–solvent interactions in phenylalanine, histidine and aqueous solution of nicotinic acid (vitamin) has been investigated by thermophysical properties. The apparent molar volume (ϕ), viscosity B-coefficient and molal refraction (RM) of phenylalanine and histidine have been studied in 0.01, 0.03 and 0.05 mol dm−3 aqueous vitamin solutions at different temperatures. Using the density data, Masson equation has been employed to obtain the limiting apparent molar volumes (ϕ) and experimental slopes (), which deduced the solute–solvent and solute–solute interactions, respectively. Using the Jones–Dole equation, the viscosity data were examined to determine the viscosity A and B coefficient. The Lorentz–Lorenz equation has been employed to determine the molar refractions (RM). The overall results established the strong solute–solvent interactions between the studied amino acids and vitamin mixture in the ternary solutions. UV-visible absorption spectra of the ternary solutions also stand in support of the results obtained.

Ursolic Acid Loaded PLGA Nanoparticles: in vitro and in vivo Evaluation to Explore Tumor Targeting Ability on B16F10 Melanoma Cell Lines

Ursolic acid (UA), a pentacyclic triterpenoid extracted from plants, shows promising inhibitory effect in different tumor bearing cell lines. In the present study we fabricated UA loaded PLGA nanoparticles (UA-NPs) as the drug carrier and thoroughly evaluated in vitro and in vivo the differential tumor targeting effects of UA and UA-NPs in B16F10 melanoma cells. Ursolic acid loaded PLGA nanoparticles were prepared by emulsion solvent evaporation technique and evaluated for particle size, polydispersity, zeta potential and drug release potency. MTT assay as well as flow cytometric and confocal microscopic analyses were done in B16F10 mouse melanoma cell lines. Formulations were labeled with technetium-99m to evaluate the biodistribution and perform scintigraphic imaging studies following intravenous administration in tumor bearing mice model. Single emulsification technique produced smooth spherical nanoparticles of small size with relatively narrow size distribution (154 ± 4.56nm). On B16F10 cell line, the formulation showed higher cytotoxicity compared to the free drug due to increased in vitro cellular uptake. The formulation was successfully radiolabeled and remained substantially (>90%) stable when incubated (37°C, 6h) separately in normal saline or freshly collected rat serum or histidine solution. The radiolabeled UA-NPs exhibited slower blood clearance and comparatively high uptake in tumor region as evidenced by biodistribution and scintigraphic studies. The in vitro and in vivo studies have proved the tumor targeting potential of UA-NPs in B16F10 melanoma cell lines.

Impact of UV disinfection on the potential of model organic-nitrogen precursors to form chlorination by-products in swimming pool water

The article presents the results of experiments on the potential of model solutions of urea, creatinine, glycine, histidine, and arginine to form several organic chlorination by-products. These precursors are the main organic-nitrogen compounds, whose sources in swimming pool water are sweat and urine of bathers. In the article, the formation potential of the following by-products has been presented and discussed: trichloromethane; monochloroacetic acid; dichloroacetic acid; trichloroacetic acid; trichloroacetonitrile; dichloroacetonitrile; 1,1-dichloropropanone; 1,1,1-trichloropropanone; chloral hydrate; and chloropicrin. The test on by-products formation potential was applied to conduct the experiments, and 24-h incubation time was applied for the swimming pool water samples, disinfected in three variants of treatment: (1) chlorination alone; (2) chlorination and Ultraviolet (UV) irradiation (cumulative dose 23.5 kJ/m2); and (3) chlorination and UV irradiation (cumulative dose 47 kJ/m2). The low-pressure UV lamp by Heraeus was used to irradiate the samples. The results of experiments have been discussed and analyzed to study the influence of UV radiation on the reactivity of individual model precursors and their potential to form halogenated organic chlorination by-products.

A simple analytical method for determining inorganic anions and formate in virgin olive oils by capillary electrophoresis with capacitively coupled contactless conductivity detection

This paper describes a novel and simple method for determining chloride, nitrate, sulfate, fluoride, and formate in virgin olive oil (VOO) by capillary electrophoresis with capacitively coupled contactless conductivity detection. The anions were extracted from VOO by a simple ultrasound-assisted aqueous liquid–liquid extraction procedure. The anions were separated in less than 3 min with good peak resolutions using a background electrolyte composed of 15 mmol L−1 histidine solution at pH 4.0, adjusted with lactic acid, and 0.6 mmol L−1 cetyltrimethylammonium hydroxide as electrosmotic flow (EOF) modifier. Tartrate was used as internal standard (I.S.). The proposed method showed good linearity and had coefficients of determination (R2) ranging from 0.9984 to 0.9999. The limits of quantification (LOQ) were between 0.01 and 0.7 mg kg−1. Recovery tests were used to evaluate the efficiency of the extraction procedure; the recovery percentages ranged from 70.2 to 118%, with a relative standard deviation (RSD) varying from 0.7 to 19.4%. The proposed method was applied to the determination of the anions in five different commercial samples of VOO.

Novel Glutathione-Capped Cadmium Telluride Quantum Dots-Based Off–On Fluorescence Sensor for Highly Sensitive and Selective Monitoring of Histidine

A novel glutathione-capped cadmium telluride quantum dots-based fluorescence “off–on” sensor was designed and applied for highly sensitive and selective monitoring of histidine in aqueous solution. To provide a platform for histidine detection, manganese ion was first employed as an effective quencher to decrease the fluorescence of glutathione-capped cadmium telluride quantum dots because of the binding of manganese ion to glutathione on the surface of quantum dots and the electron transfer from the photoexcited glutathione-capped cadmium telluride quantum dots to manganese ion. Due to its high binding affinity with manganese ion, histidine can make the manganese ion to be dissociated from the surface of glutathione-capped cadmium telluride quantum dots to form more stable complex with histidine in solution, and set free the luminescent glutathione-capped cadmium telluride quantum dots, thereby recovering the fluorescence of glutathione-capped cadmium telluride quantum dots. Experimental results showed that the recovered fluorescence intensity was directly proportional to the concentration of histidine in the range of 0.006 to 465.0 µg mL−1 with a correlation coefficient (R) of 0.9977, and the detection limit (3σ/K) was 1.82 ng mL−1. Relevant experiments also revealed that the fluorescence sensor gives excellent selectivity for histidine over other common amino acids. To further investigate perfect analysis performance, this sensor was utilized to determine histidine in synthetic samples with satisfactory results.

Conductivity and fluorescence studies on the micellization properties of sodium cholate and sodium deoxycholate in aqueous medium at different temperatures: Effect of selected amino acids

In order to add to the existing knowledge of aqueous solution behavior of bile salts in presence of amino acids, the micellization properties of sodium cholate (NaC) (1 to 20)mmol·kg−1, and sodium deoxycholate (NaDC) (0.5 to 10)mmol·kg−1 in 0.1mol·kg−1 aqueous solution of glycine, leucine, methionine, and histidine have been investigated at different temperatures (293.15 to 318.15)K at intervals of T=5K by using conductivity and fluorescence probe studies. The critical micelle concentration (CMC) values have been determined and elucidated in terms of hydrophobicity as well as hydrophilicity of NaC and NaDC in aqueous solution of these additives. Thermodynamic parameters of micellization viz. standard Gibbs free energy (ΔmicGo), standard enthalpy (ΔmicHo), and standard entropy (ΔmicSo) have also been calculated to extract information regarding the nature of micellization of bile salts in aqueous solutions. The (enthalpy+entropy) compensation plots have been interpreted to the contribution of chemical part towards micellization or stability of the micelle formed.

Synthesis and evaluation of technetium-99m-labeled bioreductive pharmacophores conjugated with amino acids and peptides for tumor imaging.

Development of molecular imaging agents to target tumor has become a major trend in nuclear medicine. With the aim to develop new potential 99mTc-radiopharmaceuticals for targeting tumor, we have synthesized 5-nitroimidazolyl amino acids and RGD-coupled 2-nitroimidazoles. Technetium-99m radiolabeling with high radiochemical purity (>90%) was achieved for all the compounds. The radiolabeled complexes exhibited substantial in vitro stability in saline, serum, and histidine solution (10(-2) m). Cell binding studies in EAC and B16F10 cell lines also revealed rapid and comparatively high cellular internalization. Among all the compounds studied, the binding of 99mTc(CO)3-5 to B16F10 cells was moderately inhibited by the competitive peptide c[RGDfV], suggesting specificity of the radioligand toward αvβ3 receptor. However, no significant displacement of bound radioligand was observed when the binding of the 99mTc-labeled complexes to above cells was challenged with excess competitive peptide. Fluorescent microscopy study provided direct evidence of intracellular localization of 5(6)-carboxyfluorescein-labeled 2-nitroimidazolyl-RGD-peptide in αvβ3-positive B16F10 mouse melanoma cell line. The ligands caused only 8-13% of hemolysis toward rat erythrocytes at concentrations as high as 100 μm. Imaging and biodistribution studies were performed in Swiss albino mice bearing induced tumor. 99mTc-1 and 99mTc(CO)3-5 demonstrated a very favorable in vivo profile. Selective uptake and retention in tumor with encouraging tumor/muscle and tumor/blood ratio and significant cellular uptake of fluorescence-labeled-2-nitroimidazolyl RGD indicate the great potentiality of the pharmacophore for further evaluation as potential molecular imaging agent in cancer diagnosis.

Ascertaining free histidine from mixtures with histidine-containing proteins using time-resolved photoluminescence spectroscopy.

The use of photoluminescent probes for differentiating free amino acids from biomolecules containing the same amino acids is challenging. Photoluminescent probes generally present similar emission spectra when in the presence of either free-amino acids or protein containing those same amino acids. Probes based on cyclometalated iridium(III) complexes Ir(L)2(sol)2 (where L is 2-phenylpyridine, 2-(2,4-difluorophenyl)pyridine, or benzo[h]quinolone, and sol is a solvent molecule) present long-lived emission when bound to histidine. This emission is tuned by the microenvironment around the complex and therefore its lifetime is different for free histidine (487 ns) than from histidine-containing proteins such as bovine serum albumin (average lifetime > 700 ns). As a proof-of-concept we demonstrate that free histidine can be discerned from a mixture with histidine-containing proteins by using time-resolved photoluminescence decays. In the presence of multiple sources of histidine, iridium(III) probes display a multiexponential decay, which can be fitted by nonlinear least-squares methods to separate the different components. Because the pre-exponential factor of the 487 ns lifetime is proportional to the concentration of free histidine, we can use it to assess the amount of free histidine in solution even in the presence of proteins such as bovine serum albumin. We also show that iridium(III) probes displaying different photoluminescence maxima can be produced by modifying the ancillary ligands of the metal complex.

Enhanced fluorescence of gold nanoclusters composed of HAuCl4 and histidine by glutathione: glutathione detection and selective cancer cell imaging.

Glutathione (GSH) can significantly and selectively enhance the fluorescence intensity of Au nanoclusters (NCs) prepared by blending HAuCl4 and histidine in solution. The quantum yield of the Au NCs after adding GSH can reach above 10%. Besides, GSH capping shifts the excitation peak of Au NCs from ultraviolet (386 nm) to visible light (414 nm) and improves the stability of the Au NCs. The cytotoxicities of the Au NCs with and without GSH for normal lung cells (ATII) and cancerous lung cells (A549) are evaluated. The GSH-capped Au NCs have much less cytotoxicity to both normal and cancer cells, as compared to those without GSH. For Au NCs without GSH, less cytotoxicity is observed in cancer cells than in normal cells. In addtion, the Au NCs can selectively detect GSH over cysteine and homocysteine, the two biothiols which commonly exist in cells that can seriously affect GSH detection. Most importantly, Au NCs without GSH can selectively image the cancer cells, especially for the liver cancer cells whose GSH content is much higher than other cell types. This property makes the Au NCs a powerful probe to distinguish cancer cells from normal cells.

Effects of Perinatal 2,3,7,8-Tetrachlorodibenzo-P-Dioxin Exposure on Development of Taste Preference in Rat Offspring

Perinatal 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (TCDD) exposure affects various motivated behaviors controlled by limbic system of the brain in offspring. In this study, effects of perinatal TCDD exposure on taste preference were investigated in the rat offspring whose dams were orally exposed to TCDD on the 15 gestational days. After weaning, offspring were given free access to six amino acid solutions with different tastes (sweet, umami, or bitter), saline (salty taste), and distilled water in a choice paradigm. In the TCDD exposed males, daily food intake was significantly decreased on Postnatal Day (P.D.) 33, whereas no differences of total fluid and any kind of solution intake were found between TCDD exposure and control groups in males. In the exposed females, daily intake of MSG was significantly lower on P.D. 32-34 respectively. Moreover, mean MSG intake rates during P.D. 29-35 was significantly decreased in TCDD exposure females. These results suggest that the TCDD-exposed females need less protein than the control females because of poorer growth than the control females, because MSG has “umami” taste, which reflects preference protein intake. In contrast, daily histidine intake on P.D. 34 was significantly increased in TCDD exposed females, and mean lysine intake rate during PND 29-35 was significantly higher than that of control group. These results suggest that rats preferred bitter taste of histidine and lysine solutions under the chemical stress of TCDD exposure. In conclusion, perinatal TCDD exposure affected development of taste preference of offspring female rats, and more study to clarify neural mechanisms is necessary in future.

Possible Anaphylaxis Due to Recombinant Factor VIIa Administration During Thoracic Aortic Surgery

Possible Anaphylaxis Due to Recombinant Factor VIIa Administration During Thoracic Aortic Surgery

Ni 2+-modulated homocysteine-capped CdTe quantum dots as a turn-on photoluminescent sensor for detecting histidine in biological fluids

The high affinity of histidine to Ni 2+ has long been recognized in metal ion affinity chromatography for the separation and purification of histidine-tagged proteins. Besides, such affinity pair has been explored in modern nanotechnology for constructing functional nanoparticle-histidine-tagged protein conjugates. However, the use of Ni 2+-histidine affinity pair in conjunction with optically-active nanomaterials for sensor design, to our knowledge, has not been reported yet. Here we report a turn-on photoluminescent sensor for histidine based on Ni 2+-modulated homocysteine (Hcy)-capped CdTe quantum dots (QDs) by taking the advantages of this well-known Ni 2+-histidine affinity pair and photoluminescent QDs. The photoluminescence of Hcy-capped CdTe QDs can be effectively quenched by Ni 2+ due to the binding of Ni 2+ to the Hcy on the surface of the QDs and the electron transfer from the photoexcited QDs to Ni 2+. The high affinity of histidine to Ni 2+ enables Ni 2+ to be dissociated from the surface of Hcy-capped CdTe QDs to form stable complex with histidine in solution, thereby recovering the photoluminescence of Hcy-capped CdTe QDs. The Ni 2+ induced photoluminescence quenching and subsequent histidine-induced photoluminescence recovery for Hcy-capped CdTe QDs build a solid base for the present QD-based turn-on photoluminescent sensor for detecting histidine. The developed QD-based sensor gives excellent selectivity for histidine over other amino acids with the limit of detection (3 s) of 0.3 μM. The relative standard deviation for 11 replicate detections of 15 μM histidine was 2.7%. The developed sensor was applied to the determination of histidine in human urine samples with recoveries from 94.4% to 106%.

Thermodynamics of solution of histidine

The enthalpies of solution of l-histidine in water at 288.15–318.15 K and 0.003–0.15 mol kg −1 were measured. The enthalpies of solution were found to be independent of the solute molality up to ∼0.1 mol kg −1. Standard enthalpies and heat capacities of solution were computed. Free energies and entropies of solution have been estimated in the temperature range studied using literature solubility data and the results of the present study. The temperature increase was found to result in a pronounced rise of the l-histidine solubility due to the significant increase of the TΔ S values. The characteristic temperatures for the thermodynamic properties of histidine aqueous solutions were estimated.

Loading capacity of carrier ampholytes – based buffers in capillary electrophoresis

Narrow pH cuts of carrier ampholytes (CAs), originally designed for IEF, have been used as BGEs in CE. Their physicochemical properties, rather high buffering capacity and low conductivity, allow very efficient protein separations under high electric field strength. Due to their isoelectric properties, CA BGEs are expected to present a low ionic concentration and consequently a low loading capacity. In this study, we developed a simple method that allows the estimation of the loading capacity of a UV-absorbing BGE by CE. We first characterized in terms of loading capacity, classical ammediol-chromate UV-absorbing BGEs and a 10 mM histidine solution, a classical isoelectric buffer. Then, the loading capacity of four different CA-based BGEs has been assessed. Experimental results have shown that the CA-based buffers were presenting a rather high loading capacity, comparable to classical buffer ones and far higher than the one of the 10 mM histidine solution.

Molecular dynamics and information on possible sites of interaction of intramyocellular metabolites in vivo from resolved dipolar couplings in localized 1H NMR spectra

Proton NMR resonances of the endogenous metabolites creatine and phosphocreatine ((P)Cr), taurine (Tau), and carnosine (Cs, β-alanyl- l-histidine) were studied with regard to residual dipolar couplings and molecular mobility. We present an analysis of the direct 1H– 1H interaction that provides information on motional reorientation of subgroups in these molecules in vivo. For this purpose, localized 1H NMR experiments were performed on m. gastrocnemius of healthy volunteers using a 1.5-T clinical whole-body MR scanner. We evaluated the observable dipolar coupling strength SD 0 ( S = order parameter) of the (P)Cr-methyl triplet and the Tau-methylene doublet by means of the apparent line splitting. These were compared to the dipolar coupling strength of the (P)Cr-methylene doublet. In contrast to the aliphatic protons of (P)Cr and Tau, the aromatic H2 ( δ = 8 ppm) and H4 ( δ = 7 ppm) protons of the imidazole ring of Cs exhibit second-order spectra at 1.5 T. This effect is the consequence of incomplete transition from Zeeman to Paschen-Back regime and allows a determination of SD 0 from H2 and H4 of Cs as an alternative to evaluating the multiplet splitting which can be measured directly in high-resolution 1H NMR spectra. Experimental data showed striking differences in the mobility of the metabolites when the dipolar coupling constant D 0 (calculated with the internuclear distance known from molecular geometry in the case of complete absence of molecular dynamics and motion) is used for comparison. The aliphatic signals involve very small order parameters S ≈ (1.4 − 3) × 10 −4 indicating rapid reorientation of the corresponding subgroups in these metabolites. In contrast, analysis of the Cs resonances yielded S ≈ (113 − 137) × 10 −4. Thus, the immobilization of the Cs imidazole ring owing to an anisotropic cellular substructure in human m. gastrocnemius is much more effective than for (P)Cr and Tau subgroups. Furthermore, 1H NMR experiments on aqueous model solutions of histidine and N-acetyl- l-aspartate (NAA) enabled the assignment of an additional signal component at δ = 8 ppm of Cs in vivo to the amide group at the peptide bond. The visibility of this proton could result from hydrogen bonding which would agree with the anticipated stronger motional restriction of Cs. Referring to the observation that all dipolar-coupled multiplets resolved in localized in vivo 1H NMR spectra of human m. gastrocnemius collapse simultaneously when the fibre structure is tilted towards the magic angle ( θ ≈ 55°), a common model for molecular confinement in muscle tissue is proposed on the basis of an interaction of the studied metabolites with myocellular membrane phospholipids.

Comprehensive Study of the Formation and Reaction of a Tethered N-Hydroxysulfosuccinimidyl Ester Used to Covalently Tether Proteins to Surfaces

A fundamental understanding of surface-reaction kinetics and mechanisms is essential to making progress on rational design of complex surface architectures used in applications as varied as biosensor devices and organic electronic devices. We present recent progress on the understanding of the carbodiimide coupling reaction frequently used to form a surface-tethered active N-hydroxysulfosuccinimide ester and the subsequent substitution of the active ester with various nucleophiles in solution. These studies were carried out using surface-enhanced Raman spectroscopy (SERS) and show that the carbodiimide coupling reaction is first order in carbodiimide concentration and zero order in N-hydroxysulfosuccinimide concentration. This reaction proceeds with a second-order rate constant of 0.062 mM-1s-1 at about 20 °C. The tethered active ester was then reacted with histidine or glucose oxidase. The reaction with histidine was found to be first order in the histidine solution concentration, indicating a simple SN2...

Integration of a contactless conductivity detector into a commercial capillary cassette: Detection of inorganic cations and catecholamines

A contactless conductivity detector integrated into the capillary cassette of Agilent 3DCE equipment is described. The detector is user-friendly, compact and easily modified. The UV detector of the 3DCE equipment is available parallel with the contactless conductivity detector increasing the detection power. Two electrolyte solutions, 2-( N-morpholino)ethanesulfonic acid–histidine solution (20 m M, pH 6.0) and ammonium acetate (10 m M, pH 4.0), were used as the separation media for inorganic cations and organic catecholamines, respectively. The detection limit for all metal cations except barium was under 0.5 mg/l, and that for four catecholamines was ca. 10 mg/l. This last value was the same order of magnitude as achieved with parallel UV detection.

Elution mechanism in electrostatic ion chromatography with histidine as an isoelectric ampholytic mobile phase

Electrostatic ion chromatography (EIC) using a zwitterionic stationary phase (formed by coating a C 18 material with a hydrophobic zwitterionic surfactant) was studied with a mobile phase comprising an aqueous solution of histidine at the pH of its isoelectric point, together with non-suppressed conductometric detection. Anions and cations were found to be eluted as separate peaks, unlike the elution behaviour observed on the same system when pure water was used as mobile phase. An explanation was suggested in terms of protonation equilibria of the overall uncharged histidine to form small amounts of histidine cations and anions in the mobile phase which could act as counterions for analyte anions and cations. This suggestion was supported by measured pH changes occurring in the bands of eluted analyte anions (a decreased pH compared to the mobile phase) and cations (an increased pH compared to the mobile phase). The analytical potential of this type of EIC is discussed.

Influence of some aromatic amino acids on the swelling behavior of acrylamide/maleic acid hydrogel

Influence of some aromatic amino acids (histidine, phenylalanine and tryptophan) on the swelling behavior of acrylamide/maleic acid hydrogel (AAm/MA) prepared by γ-radiation was investigated. Swelling tests of AAm/MA hydrogel were made in buffer solutions and amino acid solutions at various pH at 37°C. The pH values are ionization of α-carboxyl groups (pK'1), α-amino groups (pK'2) and, isoelectric points (pI) of amino acids. The swelling of AAm/MA hydrogel increased when pH values of solutions were increased. The value of equilibrium swelling of AAm/MA hydrogel was 1035% at pH 10 buffer, while it was 880% at pH 2 buffer. The values of equilibrium swelling of AAm/MA hydrogel in phenylalanine, tryptophan and histidine solutions varied among 1130–1245% at pH 10, while they were among 790–975% at pH 2. The rate constant of swelling, diffusional exponent, network parameter and, diffusion and intrinsic diffusion coefficient were calculated by swelling kinetics. Diffusion of the penetrants into the hydrogel was found to be non-Fickian character. The diffusion coefficients of the hydrogel varied between 3.33×10−6– 7.71×10−6 cm 2s−1, while the intrinsic diffusion coefficients waried between 4.03×10−6– 8.48×10−6 cm 2s−1.