Crosslinked carboxymethylchitosan-g-poly(acrylic acid) copolymer as a novel superabsorbent polymer

A novel carboxymethylchitosan-g-poly(acrylic acid) (CMCTS-g-PAA) superabsorbent polymer was prepared through graft polymerization of acrylic acid onto the chain of carboxymethylchitosan and subsequent crosslinking. It was demonstrated by FTIR spectroscopy that acrylic acid had been graft polymerized with carboxymethylchitosan. The thermal stability of the polymer was characterized by thermogravimetric analysis. By studying the swelling ratio of the polymer synthesized under different conditions, optimization conditions were found for a polymer with the highest swelling ratio. The rate of water absorption of the polymer was high, and the swelling of the polymer fitted the process of first dynamics. The swelling ratio of the polymer was pH-dependent.     

保水剂对煤矸石基质上高羊茅生长及营养吸收的影响

为探索保水剂对煤矸石废弃地上高羊茅生长及营养特征的影响,按煤矸石与土壤质量比设3种基质梯度,每种基质分别添加3种质量的保水剂,设对照(CK),共10种处理。观测和分析不同处理下高羊茅的生长高度、生物量、营养特征及SPAD值(相对叶绿素含量),结果显示:保水剂主要影响高羊茅地上部分的生物量,而煤矸石与土壤的质量比主要影响地下部分的生物量;煤矸石与土壤质量比相同条件下,添加1 g/kg的保水剂即可促进高羊茅的生长,添加2 g/kg保水剂能使高羊茅尽快适应基质环境,使其日均生长率在出苗后第2周达到峰值。煤矸石基质中添加保水剂能促使高羊茅将煤矸石基质中的营养元素从植株地下部分向地上部分转移,供植株生长需要,基质中添加1 g/kg保水剂时高羊茅对磷的吸收效果最好。此外,添加保水剂能使叶片的SPAD值增加。综合比较不同处理下高羊茅的株高、生物量、营养特征及叶片的SPAD值认为,处理6(煤矸石与土壤质量比为750:250、基质中添加2 g保水剂)与处理8(煤矸石与土壤质量比为500:500、基质中添加1 g保水剂)是适合煤矸石废弃地上高羊茅生长的较好配比。     

Evaluation of Prosopis africana Seed Gum as an Extended Release Polymer for Tablet Formulation

In the present work, an attempt has been made to screen Prosopis africana seed gum (PG), anionic polymer for extended release tablet formulation. Different categories of drugs (charge basis) like diclofenac sodium (DS), chlorpheniramine maleate (CPM), and ibuprofen (IB) were compacted with PG and compared with different polymers (charge basis) like xanthan gum (XG), hydroxypropyl methyl cellulose (HPMC-K100M), and chitosan (CP). For each drug, 12 batches of tablets were prepared by wet granulation technique, and granules were evaluated for flow properties, compressibility, and compactibility by Heckel and Leuenberger analysis, swelling index, in vitro dissolution studies, etc. It has been observed that granules of all batches showed acceptable flowability. According to Heckel and Leuenberger analysis, granules of PG-containing compacts showed similar and satisfactory compressibility and compactibility compared to granules of other polymers. PG showed significant swelling (P < 0.05) compared to HPMC, and better than CP and XG. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) study showed no interaction between drugs and polymers. From all PG-containing compacts of aforesaid drugs, drug release was sustained for 12 h following anomalous transport. Especially, polyelectrolyte complex formation retarded the release of oppositely charged drug (CPM-PG). However, extended release was noted in both anionic (DS) and nonionic (IB) drugs, maybe due to swollen gel. All compacts were found to be stable for 3-month period during stability study. This concludes that swelling and release retardation of PG has close resemblance to HPMC, so it can be used as extended release polymer for all types of drugs.KEY WORDS: chlorpheniramine maleate, diclofenac sodium, extended release, ibuprofen, Prosopis africana     

Terminalia Gum as a Directly Compressible Excipient for Controlled Drug Delivery

The exudates from the incised trunk of Terminalia randii has been evaluated as controlled release excipient in comparison with xanthan gum and hydroxypropylmethylcellulose (HPMC) using carvedilol (water insoluble) and theophylline (water soluble) as model drugs. Matrix tablets were prepared by direct compression and the effects of polymer concentration and excipients—spray dried lactose, microcrystalline cellulose and dicalcium phosphate dihydrate on the mechanical (crushing strength (CS) friability (F) and crushing strength–friability ratio (CSFR)) and drug release properties of the matrix tablets were evaluated. The drug release data were fitted into different release kinetics equations to determine the drug release mechanism(s) from the matrix tablets. The results showed that the CS and CSFR increased with increase in polymer concentration while F decreased. The ranking of CS and CSFR was HPMC > terminalia > xanthan while the ranking was reverse for F. The ranking for t ₂₅ (i.e. time for 25% drug release) at a polymer concentration of 60% was xanthan > terminalia = HPMC. The dissolution time, t ₂₅, of theophylline matrices was significantly lower (p < 0.001) than those of carvedilol matrix tablets. Drug release from the matrices was by swelling, diffusion and erosion. The mechanical and drug release properties of the tablets were significantly (p < 0.05) dependent on the type and concentration of polymer and excipients used with the release mechanisms varying from Fickian to anomalous. Terminalia gum compared favourably with standard polymers when used in controlled release matrices and could serve as a suitable alternative to the standard polymers in drug delivery.     

Study of the interaction of polyols with polymers containing n-substituted [(4-boronophenyl)methyl]-ammonio groups

Polymers, based on dextran and cellulose, having 2-{[(4-boronophenyl)-methyl]-ethylammonio}ethyl and -diethylammonio～ethyl groups were prepared. It was shown that these polymers could be employed for absorption of cis-diol compounds. The polymers were found to be highly specific towards polyols, carbohydrates, nucleosides, and nucleotides over a wide range of pH. The polymer based on DEAE-Sephadex A-25 was used in separating nucleosides, and in fractionating mononucleotides and carbohydrates. The chromatographic behavior of carbohydrates is defined by their structure and conformation, which are also responsible for different stabilities of the boronic complexes generated.     

Development of Sustained Release Capsules Containing “Coated Matrix Granules of Metoprolol Tartrate”

The objective of this investigation was to prepare sustained release capsule containing coated matrix granules of metoprolol tartrate and to study its in vitro release and in vivo absorption. The design of dosage form was performed by choosing hydrophilic hydroxypropyl methyl cellulose (HPMC K100M) and hydrophobic ethyl cellulose (EC) polymers as matrix builders and Eudragit® RL/RS as coating polymers. Granules were prepared by composing drug with HPMC K100M, EC, dicalcium phosphate by wet granulation method with subsequent coating. Optimized formulation of metoprolol tartrate was formed by using 30% HPMC K100M, 20% EC, and ratio of Eudragit® RS/RL as 97.5:2.5 at 25% coating level. Capsules were filled with free flowing optimized granules of uniform drug content. This extended the release period upto 12 h in vitro study. Similarity factor and mean dissolution time were also reported to compare various dissolution profiles. The network formed by HPMC and EC had been coupled satisfactorily with the controlled resistance offered by Eudragit® RS. The release mechanism of capsules followed Korsemeyer–Peppas model that indicated significant contribution of erosion effect of hydrophilic polymer. Biopharmaceutical study of this optimized dosage form in rabbit model showed 10 h prolonged drug release in vivo. A close correlation (R² = 0.9434) was established between the in vitro release and the in vivo absorption of drug. The results suggested that wet granulation with subsequent coating by fluidized bed technique, is a suitable method to formulate sustained release capsules of metoprolol tartrate and it can perform therapeutically better than conventional immediate release dosage form.Key words: biopharmaceutical evaluation, coated granules, metoprolol tartrate, sustained release     

Synthesis of new poly(ether–urethane–urea)s based on amino acid cyclopeptide and PEG: study of their environmental degradation

Conventional polyurethanes (PUs) are among biomaterials not intended to degrade but are susceptible to hydrolytic, oxidative and enzymatic degradation in vivo. Biodegradable PUs are typically prepared from polyester polyols, aliphatic diisocyanates and chain extenders. In this work we have developed a degradable monomer based on α-amino acid to accelerate hard segment degradation. Thus a new class of degradable poly(ether–urethane–urea)s (PEUUs) was synthesized via direct reaction of 4,4′-methylene-bis(4-phenylisocyanate) (MDI), l-leucine anhydride (LA) and polyethylene glycol with molecular weight of 1,000 (PEG-1000) as polyether soft segment. The resulting polymers are environmentally biodegradable and thermally stable. Decomposition temperatures for 5 % weight loss occurred above 300 °C by TGA in nitrogen atmospheres. Some structural characterization and physical properties of these polymers before and after degradation in soil, river water and sludge are reported. The environmental degradation of the polymer films was investigated by SEM, FTIR, TGA, DSC, GPC and XRD techniques. A significant rate of degradation occurred in PEUU samples under river water and sludge condition. The polymeric films were not toxic to E. coli (Gram negative), Staphylococcus aureus and Micrococcus (Gram positive) bacteria and showed good biofilm formation on polymer surface. Our results show that hard segment degraded selectively as much as soft segment and these polymers are susceptible to degradation in soil and water. Thus our study shows that new environment-friendly polyurethane, which can degrade in soil, river water and sludge, is synthesized.     

Evaluation of Alginate/Chitosan nanoparticles as antisense delivery vector: Formulation,optimization and in vitro characterization

Nanoparticles comprising Alginate/Chitosan polymers were prepared by pregel preparation method through drop wise addition of various concentrations of CaCl₂ to a defined concentration of Sodium Alginate. Then, Chitosan/Antisense solution with a certain N/P ratio was added to the pregel to make the nanoparticles. The effect of such parameters as polymer ratio, CaCl₂/Alginate ratio and N/P ratio on the particle size distribution and loading efficacy was studied. The optimum conditions were 1:1 (w/w) Alginate to Chitosan ratio, 0.2% CaCl₂/Alginate ratio and N/P ratio of 5 at pH 5.3. The resulting nanoparticles had a loading efficacy of 95.6% and average size of 194 nm as confirmed by PCS method and SEM images showed spherical and smooth particles. The zeta potential of optimized nanoparticles prepared by this method was about +30 mV which could result in good stability of nanoparticles during manipulation and storage.     

Evaluation of Matrix Tablets Based on Eudragit?E100/Carbopol?971P Combinations for Controlled Release and Improved Compaction Properties of Water Soluble Model Drug Paracetamol

The purpose of this work was to investigate the influence of Eudragit®E100 polymer in modifying the release rates and compaction properties of water soluble model drug paracetamol from Carbopol®971P NF polymer matrix tablets prepared by direct compression. The effects of the ratio of the two polymers, the total polymeric content, and the tablets mechanical strength on paracetamol release rates were investigated. Dissolution studies were conducted using USP XX Π rotating paddle apparatus at 50 rpm and 37°C at three different stages (pH 1.2, 4.8, and 6.8). Results showed that the polymers combination improved significantly the compaction properties of paracetamol tablets as evident by the higher crushing strengths (8.3 ± 0.4 Kp) compared to polymer-free tablets (3.4 ± 0.2 Kp) at intermediate compression pressure of 490 MPa. When combined with Carbopol®971P NF, Eudragit®E100 was found to be capable of extending paracetamol release for more than 12 h compared to 1 h for polymers-free tablets. The combined polymers were able to control paracetamol release in a pH independent pattern. The f2 (similarity factor) analysis showed that the ratio between the polymers and the total polymer concentration exhibited significant impact on drug release rates. In conclusion, Eudragit®E100 when combined with Carbopol®971P NF was capable of improving the compaction and sustained release properties of paracetamol. Korsmeyer–Peppas model was found to be the most suitable for fitting drug release data. The polymer combinations can potentially be used to control the release rates of highly water soluble drugs.KEY WORDS: Carbopol®971P NF, Eudragit®E100, matrix tablet, pH-independent release, sustained     

Preparation of Polyamide Nanocapsules of Aloe vera L. Delivery with In Vivo Studies

Aloe vera is the oldest medicinal plant ever known and the most applied medicinal plant worldwide. The purpose of this study was to prepare polyamide nanocapsules containing A. vera L. by an emulsion diffusion technique with in vivo studies. Diethyletriamine (DETA) was used as the encapsulating polymer with acetone ethyl acetate and dimethyl sulfoxide (DMSO) as the organic solvents and Tween and gelatin in water as the stabilizers. Sebacoyl chloride (SC) monomer, A. vera L. extract, and olive oil were mixed with the acetone and then water containing DETA monomer was added to the solution using a magnetic stirrer. Finally, the acetone was removed under vacuum, and nanocapsules were obtained using a freeze drier. This study showed that the size of the nanocapsule depends on a variety of factors such as the ratio of polymer to oil, the concentration of polymers, and the plant extract. The first sample is without surfactant and the size of nanocapsules in the sample is 115 nm. By adding surfactant, nanocapsules size was reduced to 96 nm. Nanocapsules containing A. vera were administered to rats and the effects were compared with a normal control group. The results showed that in the A. vera group, the effect is higher. The nanocapsules were identified by scanning electron microscopy (SEM), zeta potential sizer (ZPS), and Fourier-transform infrared spectroscopy (FT-IR).KEY WORDS: Aloe vera L., in vivo, medicinal plant, nanocapsule, polyamide nanocapsule     

Influence of the Component Excipients on the Quality and Functionality of a Transdermal Film Formulation

The influence of formulation variables, i.e., a hydrophilic polymer (Methocel^® E15) and a film-forming polymer (Eudragit^® RL 100 and Eudragit^® RS 100), on the physicochemical and functional properties of a transdermal film formulation was assessed. Several terpenes were initially evaluated for their drug permeation enhancement effects on the transdermal film formulations. d-Limonene was found to be the most efficient permeation enhancer among the tested terpenes. Transdermal film formulations containing granisetron (GRN) as a model drug, d-limonene as a permeation enhancer, and different ratios of a hydrophilic polymer (Methocel^® E15) and a film-forming polymer (Eudragit^® RL 100 or Eudragit^® RS 100) were prepared. The prepared films were evaluated for their physicochemical properties such as weight variation, thickness, tensile strength, folding endurance, elongation (%), flatness, moisture content, moisture uptake, and the drug content uniformity. The films were also evaluated for the in vitro drug release and ex vivo drug permeation. The increasing ratios of Methocel^®:Eudragit^® polymers in the formulation linearly and significantly increased the moisture content, moisture uptake, water vapor transmission rate (WVTR), and the transdermal flux of GRN from the film formulations. Increasing levels of Methocel^® in the formulations also increased the rate and extent of the GRN release and the GRN permeation from the prepared films.KEY WORDS: film-forming polymers, hydrophilic polymers, permeation enhancers, transdermal films     

Thermocontrol of solute permeation across polymer membrane composed of poly(N,N-dimethylaminoethyl methacrylate) and its copolymers

Polymer membranes composed ofN,N-dimethylaminoethyl methacrylate (DMAEMA) and acrylamide (AAm) (or ethyl acrylamide (EAAm)) were prepared to demonstrate the thermocontrol of solute permeation. Poly DMEMA has a lower critical solution temperature (LCST) at around 50°C in water. With the copolymerization of DMAEMA with AAm (or EAAm), a shift in the LCST to a lower temperature was observed, probably due to the formation of hydrogen bonds between the amide andN,N-dimethylamino groups. However, the temperature-induced phase transition of poly (DMAEMA-co-EAAm) did not show a similar trend to that of poly (DMAEMA-co-AAm) in the gel state. The hydrogen bonds in poly (DMAEMA-co-EAAm) were significantly disrupted with the formation of a gel network, which led to a difference in the swelling behavior of polymer gels in response to temperature. To apply these polymers to temperature-sensitive solute permeation, polymer membranes were prepared. The permeation pattern of hydrocortisone, used as the model solute, was explained based on the temperature-sensitive swelling behavior of the polymer membranes.     

Preparation,Characterization and <Emphasis Type="Italic">In Vitro</Emphasis> / <Emphasis Type="Italic">In Vivo</Emphasis> Evaluation of Oral Time-Controlled Release Etodolac Pellets

The objective of this study was to prepare time-controlled release etodolac pellets to facilitate drug administration according to the body’s biological rhythm, optimize the drug’s desired effects, and minimize adverse effects. The preparation consisted of three laminal layers from center to outside: the core, the swelling layer, and the insoluble polymer membrane. Factors influenced the core and the coating films were investigated in this study. The core pellets formulated with etodolac, lactose, and sodium carboxymethyl starch (CMS-Na) were prepared by extrusion-spheronization and then coated by a fluidized bed coater. Croscarmellose sodium (CC-Na) was selected as the swelling agent, and ethyl cellulose (EC) as the controlled release layer. The prepared pellets were characterized by scanning electron microscopy and evaluated by a dissolution test and a pharmacokinetic study. Compared with commercial available capsules, pharmacokinetics studies in beagle dogs indicated that the prepared pellets release the drug within a short period of time, immediately after a predetermined lag time. A good correlation between in vitro dissolution and in vivo absorption of the pellets was exhibited in the analysis.     

Synthesis and properties of thermo- and pH-sensitive poly(N-isopropylacrylamide)/polyaspartic acid IPN hydrogels

Various interpenetrating polymer network (IPN) hydrogels with sensitivity to temperature and pH were prepared by introducing the pH-sensitive polymer polyaspartic acid (PASP) hydrogel, into the poly(N-isopropylacrylamide) (PNIPAAm) hydrogel system for the purpose of improving its response rate to temperature. The morphologies and thermal behavior of the prepared IPN hydrogels were studied by both scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The IPN hydrogels showed a large and uneven porous network structure, without showing the common PNIPAAm hydrogel structure. The paper moreover studied their swelling properties, such as temperature dependence of equilibrium swelling ratio, shrinking kinetics, re-swelling kinetics and oscillatory swelling behavior in water. The swelling experiment results revealed that IPN hydrogels exhibited much faster shrinking and re-swelling in function of the composition ratio of the two network components. These fast responsive hydrogels foster potential applications in biomedical and biotechnology fields.     

Atom transfer radical polymerization of N-(ω-alkylcarbazolyl)methacrylates via the use of novel heteroleptic Ru(II) polypyridyl initiator

cis-Dichloro-bis(2-(2-pyridyl)-4-carbonylmethylquinoline)ruthenium (II) complex was synthesized and its structure, electrochemical, electronic absorption and emission properties were determined. A derivative Ru(II) complex with radical initiating sites was employed in the atom transfer radical polymerization (ATRP) of functional N-(ω^′-alkylcarbazoly)methacrylates to provide linear metallopolymers with the metal chromophores at one termini of the polymer chain. These polymers were characterized by gel permeation chromatography in combination with low-angle laser light-scattering, UV-Vis and emission spectroscopy to verify the covalent attachment of the metal chromophores to the polymer chain. The polymers thermal transitions and thermal stabilities were also investigated by differential scanning calorimetry and thermogravimetric analysis.     

Preparation of <Emphasis Type="Italic">in situ</Emphasis> Injectable Chitosan/Gelatin Hydrogel Using an Acid-tolerant Tyrosinase

An in situ injectable chitosan/gelatin hydrogel was formed under slightly acidic conditions (pH 4.0 ~ 4.5) using an acid-tolerant tyrosinase, tyrosinase-CNK. A homogeneous chitosan/tyrosinase-CNK solution was prepared in one part of a dual-barrel syringe, and highly soluble gelatin in distilled water was prepared in the other part of the syringe without any additional crosslinking materials. Chitosan/gelatin hydrogel was formed in situ by simple injection of the solutions at room temperature followed by curing at 37°C. However, conventional mushroom tyrosinase did not catalyze this permanent gel formation. Tyrosinase- CNK-catalyzed glycol chitosan/gelatin hydrogel was similarly formed by this in situ injection approach. The hydrogels exhibited a high swelling ratio of 20-fold their own weight, interconnected micropores with an average diameter of approximately 260 μm and in vitro biodegradability suitable for tissue engineering and drug delivery applications. These results showed that tyrosinase-CNK-mediated chitosan/gelatin hydrogel formation has remarkable potential for the development of novel formulations for in situ injectable gel-forming systems.     

Fluorescence labeling method for estimation of soluble polymers in the living material

The highly fluorescent derivatives of fluorescein, bearing the aliphatic primary amino groups, N-(2-aminoethylcarbonyl)-5(6)-aminofluorescein and 5-[N′-(2-aminoethyl)thioureido]fluorescein, were prepared for labeling of soluble polymers. The absorption and emission properties of these labels and polymers labeled with them were compared with properties of fluorescein and fluorescein isothiocyanate (FITC)-bovine serum albumin conjugate. Effects of the chemical structure of the polymer on the relative fluorescence quantum yield of a covalently attached label were evaluated using ionogenic, olefinic, or phenolic groups in side chains. The fluorescence of labeled polymers was adequate for their tracing in all the cases studied. The most pronounced quenching of fluorescence in the presence of phenolic groups is comparable with the quenching of fluorescence of FITC observed in FITC-protein conjugates. The long-term stability of the polymer-fluorochrome bond was checked in solutions of pH 2.10, 7.46, and 11.84; a higher stability of simple amide over amide plus the thiourea bond was found. The quantitative method of measurement of the concentration of labeled polymers in the biological material in a range of about 10 ng was developed; factors affecting the reproducibility are discussed.     

Characterization and In Vitro Drug Release Studies of a Natural Polysaccharide Terminalia catappa Gum (Badam Gum)

The main objective of the present study is the physicochemical characterization of naturally available Terminalia catappa gum (Badam gum [BG]) as a novel pharmaceutical excipient and its suitability in the development of gastroretentive floating drug delivery systems (GRFDDS) to retard the drug for 12 h when the dosage form is exposed to gastrointestinal fluids in the gastric environment. As BG was being explored for the first time for its pharmaceutical application, physicochemical, microbiological, rheological, and stability studies were carried out on this gum. In the present investigation, the physicochemical properties, such as micromeritic, rheological, melting point, moisture content, pH, swelling index, water absorption, and volatile acidity, were evaluated. The gum was characterized by scanning electron microscopy, differential scanning calorimetry (DSC), powder X-ray diffraction studies (PXRD), and Fourier transform infrared spectroscopy (FTIR). Gastroretentive floating tablets of BG were prepared with the model drug propranolol HCl by direct compression methods. The prepared tablets were evaluated for all their physicochemical properties, in vitro buoyancy, in vitro drug release, and rate order kinetics. PBG 04 was selected as an optimized formulation based on its 12-h drug release and good buoyancy characteristics. The optimized formulation was characterized with FTIR, DSC, and PXRD studies, and no interaction between the drug and BG was found. Thus, the study confirmed that BG might be used in the gastroretentive drug delivery system as a release-retarding polymer.KEY WORDS: badam gum, floating, gastroretentive, propranolol HCl, Terminalia catappa     

Immobilization of Candida cylindracea lipase on poly lactic acid,polyvinyl alcohol and chitosan based ternary blend film: Characterization,activity, stability and its application for N-acylation reactions

The ecofriendly ternary blend polymer film was prepared from the chitosan (CH), polylactic acid (PLA) and polyvinyl alcohol (PVA). Immobilization of Candida cylindracea lipase (CCL) was carried out on ternary blend polymer via entrapment methodology. The ternary blend polymer and immobilized biocatalyst were characterized by using N₂ adsorption–desorption isotherm, SEM, FTIR, DSC, and (%) water content analysis through Karl Fischer technique. Biocatalyst was then subjected for the determination of practical immobilization yield, protein loading and specific activity. Immobilized biocatalyst was further applied for the determination of biocatalytic activity for N-acylation reactions. Various reaction parameters were studied such as effect of immobilization support (ratio of PLA:PVA:CH), molar ratio (dibutylamine:vinyl acetate), solvent, biocatalyst loading, time, temperature, and orbital speed rotation. The developed protocol was then applied for the N-acylation reactions to synthesize several industrially important acetamides with excellent yields. Interestingly, immobilized lipase showed fivefold higher catalytic activity and better thermal stability than the crude extract lipase CCL. Furthermore various kinetic and thermodynamic parameters were studied and the biocatalyst was efficiently recycled for four successive reuses. It is noteworthy to mention that immobilized biocatalyst was stable for period of 300 days.     

The relationship between surface tension and the industrial performance of water-soluble polymers prepared from acid hydrolysis lignin, a saccharification by-product from woody materials

In this study, water-soluble anionic and cationic polymers were prepared from sulfuric acid lignin (SAL), an acid hydrolysis lignin, and the relationship between the surface tension of these polymers and industrial performance was examined. The SAL was phenolized (P-SAL) to enhance its solubility and reactivity. Sulfonation and the Mannich reaction with aminocarboxylic acids produced water-soluble anionic polymers and high-dispersibility gypsum paste. The dispersing efficiency increased as the surface tension decreased, suggesting that the fluidity of the gypsum paste increased with the polymer adsorption on the gypsum particle surface. Water-soluble cationic polymers were prepared using the Mannich reaction with dimethylamine. The cationic polymers showed high sizing efficiency under neutral papermaking conditions; the sizing efficiency increased with the surface tension. This suggests that the polymer with high hydrophilicity spread in the water and readily adhered to the pulp surface and the rosin, showing good retention.