Synthesis and characterization of gelatin based polyester urethane scaffold

For tissue engineering purpose two gelatin based polyester urethane scaffolds of different compositions were prepared from lactic acid, polyethylene glycol 400 (PEG 400) and characterized by FTIR, XRD for their mechanical and morphological properties using SEM and optical microscopic analyses. Degradation and swelling studies of gelatin based polyester urethane scaffolds in phosphate buffer saline (PBS) were performed. Human keratinocyte cells were cultured within these scaffolds, which showed good cell adherence and proliferation.     

Synthesis, characterization, and antimicrobial activity of nano-hydroxyapatite-zinc for bone tissue engineering applications

The bone implants used in tissue repair are susceptible to infections caused by staphylococci, specifically Staphylococcus aureus. Hence, the development of better biological materials that provide antimicrobial activity in bone tissue engineering is required. The nanoparticles of hydroxyapatite (nHAp) and nHAp dopped with Zn (nHAp-Zn) were prepared by the wet chemical method and the ion exchange method, respectively. They were characterized using SEM, AFM, FTIR and XRD. The antibacterial activity of nHAp and nHAp-Zn was determined with Gram-negative and Gram-positive bacterial strains. The results indicated that nHAp alone was acting as an inert matrix and when substituted with Zn, it showed better antibacterial activity. The nHAp-Zn was found to be non-toxic to osteoprogenitor cells. Thus, due to the antimicrobial property of nHAp-Zn nanoparticles, we suggest that they would have potential applications towards bone tissue engineering.     

Synthesis,characterization and in vitro studies of pegylated melphalan conjugates

Melphalan, a drug used for the treatment of breast, ovaries and a certain type of cancer in the bone marrow, was conjugated to linear methoxy poly (ethylene glycol) (M-PEG) of 2000 and 5000, Da. An ester linkage between polymer and drug was used in the coupling to yield a polymeric prodrug. Purified esters were characterized by Maldi-Tof and IR spectroscopy methods. The modification allowed overcoming the known melphalan aqueous solubility problem (0.1 µg/ml) leading us to obtain a polymer-drug bioconjugate more suitable for oral and parental administration. It was found that molecular weight of M-PEG is critical for the conjugates stability, aqueous solubility (80 times and 123 times higher aqueous solubility for M-PEG 2000 and M-PEG 5000, respectively), and hemolytic activity. The melphalan caused 100% hemolysis above the concentration 3.5 µg/ml in 1?h. whereas conjugate of M-PEG 2000 and M-PEG 5000 shows 81.3?±?0.5% and 48.8?±?1.5% hemolysis, respectively at 32 µg/ml after1?h. Further In vitro anticancer activity of melphalan and its conjugates was performed with breast cancer MCF-7 cell lines. It shows that LD50 concentration was higher 1.14 and 2 µm for M-PEG 2000 and M-PEG 5000, respectively in comparison to pure melphalan (0.74 µm). Above studies revealed improved pharmacokinetics properties upon conjugation.     

Synthesis,characterization, and antimicrobial activity of poly(GMA-co-EGDMA) polymer decorated with silver nanoparticles

Composite consisting of silver nanoparticles coordinated to poly(GMA-co-EGDMA) macroporous copolymer was prepared by attachment of amino group to the poly(GMA-co-EGDMA) in the reaction with ethylene diamine, and consequent reduction of silver ions with amino groups at elevated temperature. The infrared measurements indicated that surface of silver nanoparticles is passivated through the coordination of the lone pair on the N atom of the imine present in the skeleton of the poly(GMA-co-EGDMA) copolymer. The inductively coupled plasma atomic emission, UV–Vis reflection spectroscopy, X-ray diffraction, and transmission electron microscopy measurements revealed the high content (52 wt%) of well-separated silver nanoparticles in the size range of 5–10 nm onto composite. Antimicrobial efficiency of composite was tested against Gram-negative bacteria E. coli, Gram-positive bacteria S. aureus, and fungus C. albicans in wide concentration range of composite. The composite ensured almost maximum reduction of both bacteria, while the fungi reduction reached 96.5 %.     

明胶改性聚酰胺酸的合成与表征

通过明胶链上的-NH_2与低分子酸酐封端的聚酰胺酸链端酸酐首先在较高温度下缩合反应生成改性预聚体,然后再对改性预聚体扩链,得到明胶改性聚酰胺酸.通过测定明胶改性聚酰胺酸的特性黏度,研究了改性预聚体反应阶段不同反应条件对聚合物特性黏度的影响,同时采用红外光谱和示差扫描量热测定了明胶改性聚酰胺酸的结构与热性能.结果表明,在改性预聚体合成阶段,当明胶用量为35%、反应温度为40℃和反应时间为25min时,明胶改性聚酰胺酸的特性黏度最大.经过明胶改性,改变了聚酰胺酸的结构,使其化学亚胺化薄膜的玻璃化温度比聚酰胺酸化学亚胺化薄膜的降低39℃.     

对氨基苯甲酸壳聚糖酯的制备、表征及抗菌活性

壳聚糖(CTS)经氨基保护合成席夫碱,再与由对氨基苯甲酸和氯化亚砜制备的对氨基苯甲酰氯反应,产物在一定pH下氨基去保护得到了对氨基苯甲酸壳聚糖酯(ABCTSE)。产物经FT-IR、1H NMR、13C NMR进行结构表征,证实为目标产物;由元素分析得到所制得壳聚糖酯的酯化度为16.8%、40.4%;室温下,壳聚糖衍生物在蒸馏水及有机试剂中的溶解性比壳聚糖更好;产物的TG和DTG分析结果表明所制得壳聚糖酯的稳定性稍低于壳聚糖。另外,由于分子结构中两个氨基的存在,其溶于弱酸性溶液后随着形成—NH3+的增多,使其在抑菌方面有更大优势。     

Preparation and antimicrobial activity of gelatin microparticles containing propolis against oral pathogens

Gelatin microparticles containing propolis ethanolic extractive solution were prepared by spray-drying technique. Particles with regular morphology, mean diameter ranging of 2.27 μm to 2.48 μm, and good entrapment efficiency for propolis were obtained. The in vitro antimicrobial activity of microparticles was evaluated against microorganisms of oral importance (Enterococcus faecalis, Streptococcus salivarius, Streptococcus sanguinis, Streptococcus mitis, Streptococcus mutans, Streptococcus sobrinus, Candida albicans, and Lactobacillus casei). The utilized techniques were diffusion in agar and determination of minimum inhibitory concentration. The choice of the method to evaluate the antimicrobial activity of microparticles showed be very important. The microparticles displayed activity against all tested strains of similar way to the propolis, showing greater activity against the strains of E. salivarius, S. sanguinis, S. mitis, and C. albicans.     

Synthesis,characterization and antimicrobial activity of AgFeO<Subscript>2</Subscript> delafossite

AgFeO₂ delafossite was successfully prepared by a facile and low-cost method which was flash auto-combustion technique. X-ray diffraction pattern (XRD) confirmed that the sample was in the nanosize range. Also, the morphology analyzed by high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) clarified that AgFeO₂ delafossite was in the nanoscale range. The composition of the sample was determined using energy dispersive X-ray (EDX) analysis. The magnetic properties assured that the sample had ferromagnetic behavior. The optical properties were measured for the investigated sample and the energy gap was 3.4 eV. The antimicrobial activities were screened against Gram positive and Gram negative bacteria and the results revealed a strong antibacterial activity of AgFeO₂ delafossite. Moreover, Fungi activity was studied against Aspergillus flavus and Candida albicans and the results revealed that no activity by adding AgFeO₂ delafossite had happened. The application of this study promotes the use of AgFeO₂ as antibacterial agent.     

Synthesis and characterization of ZnO nanoparticles prepared in gelatin media

Zinc oxide nanoparticles (ZnO-NPs) were synthesized via the sol-gel method in gelatin media. Long-chain gelatin compounds were utilized to terminate the growth of ZnO-NPs and to stabilize them. The ZnO-NPs were characterized by a number of techniques, such as X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), and high-magnification transmission electron microscopy (TEM). The ZnO-NPs calcined at different temperatures exhibited a hexagonal (wurtzite) structure with sizes from 30 to 60 nm. The influence of the calcination temperature on the morphology of ZnO-NPs was also investigated. The results showed that gelatin is an interesting material that can be used as a stabilizer in the sol-gel technique for preparing small ZnO-NPs.     

可控降解抗感染材料的合成和表征

在聚己内酯(PCL)与六亚甲基二异氰酸酯(HDI)缩合体系中加入抗菌药物环丙沙星(CF),制备CF嵌入聚氨酯(PU)主链的聚氨酯前药CFPU。用UV、FTIR、H-NMR表征其结构;GPC法测定分子量;UV法测定载药率;摸索影响其分子量和载药率的主要因素;并用琼脂稀释法测定其胆固醇酯酶(CE)降解液对金黄色葡萄球菌的抗菌活性。结果表明,确已成功制得目标产物;PCL浓度和HDI加料方式分别对其平均分子量和载药率有较大影响;而其CE降解液对金黄色葡萄球菌具有抗菌活性。因此,当其用作医用内植物的涂层材料时,能被炎症组织所分泌的CE可控降解为这种具抗菌活性的降解液,从而可发挥抗感染作用。     

Synthesis, characterization and catalytic activity of CdO nanocrystals

In this paper, we report the synthesis of nanocrystalline cadmium oxide (CdO) and its characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Its catalytic activity was investigated on the thermal decomposition of 1,2,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), ammonium perchlorate (AP), hydroxyl terminated polybutadiene (HTPB) and composite solid propellants (CSPs) using thermogravimetric analysis (TG), simultaneous thermogravimerty and differential scanning calorimetry (TG-DSC) and ignition delay measurements. Kinetics of thermal decomposition of AP + CdO has also been investigated using model free (isoconversional) and model-fitting approaches which have been applied to data for isothermal TG decomposition. All these studies show enhancement in the rate of decomposition of AP, HTPB and CSPs but no effect on HMX. The burning rate of CSPs has also been found to be increased with CdO nanocrystals.     

Nucleic acid based polymer and nanoparticle conjugates: Synthesis,properties and applications

Nucleic acid based fabrication of nanomaterials has fascinated scientists since the past two decades and exciting challenges have been surmounted. Recently, nucleic acid is successfully combined with other nanometre-scale entities, sometimes by modifying with chemical functional groups, to obtain a wide range of nanomaterials which in certain cases have been characterized with atomic level precision. These nanomaterials are highly focused due to their new physico-chemical properties, which confer several advantages in multi-disciplinary field of research leading to advanced technologies. This review highlights the systematic advances in the synthesis, properties (optical and electronic) and versatile applications of nucleic acid based nano-biomaterials produced from polymer and metal or semiconductor nanoparticles.     

Synthesis and characterization of silver nanoparticles and their antimicrobial efficacy

An efficient protocol for synthesis of silver nanoparticles (AgNPs) using the combination of aqueous extract of Tinospora cordifolia leaves and 5 mM silver nitrate (AgNO₃) solution was developed. This study revealed that bioactive compounds present in the extract function as stabilizing and capping agent for AgNPs. Scanning electron microscope and transmission electron microscope studies confirm the structure and surface morphology of the AgNPs. The size of synthesized AgNPs was in the range of 30–50 nm having spherical morphology. The crystalline nature of NPs was defined by the X-ray diffraction pattern. The AgNPs were found to be toxic against pathogenic bacteria such as Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), and Staphylococcus aureus (ATCC 29213) and against plant pathogenic fungi Fusarium oxysporum (MTCC 8608) and Sclerotinia sclerotiorum (MTCC 8785). The use of AgNPs as antibacterial and antifungal agent is advantageous over other methods for control of pathogenic microorganisms, and it can be of great importance in developing novel drugs for curing many lethal diseases.     

Synthesis and characterization of MWCNT/TiO2 /Au nanocomposite for photocatalytic and antimicrobial activity.

A novel combination of titanium oxide (TiO₂)/gold (Au)/multiwalled carbon nanotubes (MWCNTs) nanocomposite (NC) was synthesised by sol– gel method. MWCNT functionalisation by modified Hummers method. TiO₂ /Au nanoparticles (NPs) were synthesised by biological method using Terminalia chebula bark extract. MWCNT/TiO₂ /Au NC samples were characterised by X‐ray diffraction, ultraviolet–visible–diffuse reflectance spectra, microRaman, scanning electron microscopy and high‐resolution‐transmission electron microscopy analyses. The photocatalytic performance of the obtained for NC toward the decomposition of congo‐red and the antimicrobial activity for inhibition of Gram positive (Bacillus subtilis, Streptococcus pneumonia and Staphylococcus aureus), Gram negative (Shigella dysenderiae, Proteus vulgaris and Klebsiella pneumonia) and fungal strains have been evaluated and the results are compared with positive control ampicillin. The metal and metal–oxide NPs have a lower sorption capacity. The herbicidal bond to the tested CNTs by the combination of electron donor–acceptor interactions and hydrogen bonds. In particular, the dispersion of NC and control of sodium borohydride, it has more efficient effect on the photodegradation and antibacterial activity of positive control of ampicillin. The NC material has exhibited maximum photodegradation and antibacterial activity results of zone of inhibition when compared with control samples.Inspec keywords: nanocomposites, nanoparticles, titanium compounds, gold, multi‐wall carbon nanotubes, nanofabrication, sol‐gel processing, catalysis, photodissociation, antibacterial activity, microorganisms, X‐ray diffraction, reflectivity, Raman spectra, ultraviolet spectra, visible spectra, hydrogen bonds, scanning electron microscopy, transmission electron microscopy, dyes, sorption, nanobiotechnologyOther keywords: titanium oxide‐gold‐multiwalled carbon nanotubes nanocomposite, sol‐gel method, photocatalytic activity, antimicrobial activity, MWCNT functionalisation, modified Hummers method, nanoparticles, biological method, Terminalia chebula bark extract, X‐ray diffraction, ultraviolet‐visible‐diffuse reflectance spectra, microRaman spectra, scanning electron microscopy, high‐resolution‐transmission electron microscopy, congo‐red decomposition, Gram positive bacteria, Bacillus subtilis, Streptococcus pneumonia, Staphylococcus aureus, Shigella dysenderiae, Proteus vulgaris, Klebsiella pneumonia, fungal strains, Gram negative bacteria, sorption capacity, herbicidal bond, electron donor‐acceptor interactions, hydrogen bonds, sodium borohydride, photodegradation, metal‐oxide nanoparticles, C‐TiO₂ ‐Au     

Synthesis,characterisation and antimicrobial activity of manganese- and iron-doped zinc oxide nanoparticles

The present work reports study on antimicrobial activity of pure and doped ZnO nanocomposites. Polyvinyl pyrrolidone capped Mn- and Fe-doped ZnO nanocomposites were synthesised using simple chemical co-precipitation technique. The synthesised materials were characterised using transmission electron microscope (TEM), X-ray powder diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), Fourier transform infrared (FTIR) spectroscopy and ultraviolet (UV) visible spectroscopy. The XRD and TEM studies reveal that the synthesised ZnO nanocrystals have a hexagonal wurtzite structure with average crystalline size ～7–14 nm. EDXRF and FTIR study confirmed the doping and the incorporation of impurity in ZnO nanostructure. The antimicrobial activities of nanoparticles (NPs) were studied against fungi, gram-positive and gram-negative bacteria using the standard disc diffusion method. The photocatalytic activities of prepared NPs were evaluated by degradation of methylene blue dye in aqueous solution under UV light irradiation. Experimental results demonstrated that ZnO NPs doped with 10% of Mn and Fe ions showed maximum antimicrobial and photodegradation efficiency in contrast with that of the 1% loading. The enhancement in antimicrobial effect and photocatalytic degradation is attributed to the generation of reactive oxygen species due to the synergistic effects of Mn and Fe loading.     

Preparation and antimicrobial activity of poly (vinyl chloride)/gelatin/montmorillonite biocomposite films

The aim of this study was using a novel antimicrobial thermoplastic plasticizer based on aliphatic anhydride derivative dodecenyl succinic anhydride (DSA) for blending poly (vinyl chloride), PVC, with gelatin in presence of montmorillonite (MMT) using Brabender via polymer melting technique. This anhydride-based plasticizer blended the membrane ingredients homogenously under melting process. The used plasticizer exhibited high performance antimicrobial potency for some biomedical and industrial applications. The prepared biocomposite films were evaluated for antimicrobial activity using agar disc diffusion method against gram-positive and gram-negative bacteria such as: Staphylococcus aureus (S. aureus), Klebsiella pneumonia (K. pneumonia), Bacillus cereus (B. cereus), Bacillus subtilis (B. subtilis) and Escherichia coli (E. coli). The majority of these biocomposites, except the plasticized PVC with DOP, have shown inhibitory effect at different concentrations (1.0–20) mg/ml against all above mentioned bacteria. However, C. albicans and A. niger were the most resistant strains.     

Synthesis, characterization and electrocatalytic activity of fused gold nanoparticles

This paper describes the synthesis of fused spherical gold nanoparticles (AuNPs) and their electrocatalytic activity towards the oxidation of hydroxylamine (HA). Fused AuNPs were prepared by one-pot synthesis using 2-mercapto-4-methyl-5-thiazoleacetic acid (TAA) as a stabilizing agent and sodium borohydride (NaBH4) as a reducing agent. The HR-TEM images showed that two individual AuNP were joined via on its surface with a size range of approximately 7 nm and a length of approximately 15 nm diameter. The pH studies showed that the synthesized fused AuNPs was stable at pH > 8. This indicated that the carboxylate ion present on the TAA molecule stabilized the AuNPs from aggregation. Further, the fused AuNPs were utilized for the electrocatalytic oxidation of hydroxylamine (HA) after immobilized them on (3-mercaptopropyl)-trimethoxysilane (MPTS) sol-gel film modified Au electrode. The AuNPs modified electrode showed an excellent electrocatalytic activity towards the oxidation of HA in 0.2 M phosphate buffer solution (pH 7.2) by shifting its oxidation potential to 100 mV less positive and enhancing its oxidation current for more than three times when compared to bare Au electrode. Further, it was found that the fused AuNPs modified electrode showed greater electrocatalytic activity towards HA than the spherical AuNPs modified electrodes.     

Synthesis, characterization, and antitumoral activity of polyoxometalate loaded starch nanocomplexes

Using a reverse-phase microemulsion polymerization method and an encapsulating method, polyoxometalates (POMs) K6SiW11TiO40 incorporating starch microspheres have been prepared and structurally characterized by elemental analyses, IR, UV-vis, and NMR spectroscopy. The size of SiW11TiO40/starch particles is about 40-60 nm. The polyoxometalate encapsulated by a starch microsphere retains the parent structure. The starch microsphere is a good carrier, as it is able to enhance the antitumoral activity of POMs and decrease the toxicity of POMs as well.     

Synthesis, characterization, and catalytic activity of nitridated magnesium silicate catalysts

Amorphous and crystalline magnesium silicates (MgSils) were prepared by sol–gel and template-assisted hydrothermal synthesis methods, respectively. The obtained materials were nitridated with NH₃ at 300, 500, and 800 °C for 24 and 48 h generating nitridated MgSil catalysts. The catalysts were characterized by XRD, FTIR, TG–MS, N₂-physisorption, Hammett indicators, and elemental analysis methods. MgSils nitridated at 300 °C were found to be more active for the Knoevenagel condensation reaction, compared to those nitradated at 500 or 800 °C. A larger amount of nitrogen was incorporated in the framework of amorphous MgSil compared to the crystalline MgSil. FTIR analysis indicated the presence of NH _x species, which were known to form upon reaction between NH₃ and M-OH groups. It was also found that the presence of Si–OH and Mg–OH groups along with the basic –NH₂ functional groups is responsible for the enhanced catalytic activity of the low-temperature nitridated catalysts.     

Synthesis, characterization, and antibacterial activity of silver-doped silica nanocomposite particles

Silver nanoparticles were adsorbed preferentially on silica surface to form composite particles using a reverse micelle process that stabilizes the silver particles by an anionic sodium bis(2-ethylhexyl) sulfosuccinate (AOT) surfactant in isooctane solvent together with the silica particles in which their surface being mediated by a cationic poly(allylamine hydrochloride) (PAH) polyelectrolyte. The heterogeneous adsorption was rendered by both electrostatic attraction and hydrophilic/hydrophobic interaction, and was carried out in multiple deposition cycles. The resulting nanocomposite particles were characterized by zeta-potential measurement, electron microscopy, X-ray diffractometry, field-emission electron spectroscopy for chemical analysis (ESCA), and inductively coupled plasma analysis, respectively. In addition, antibacterial activity of the composite particles was examined against Escherichia coli (E. coli) in aqueous environment.