Influence of native starch's properties on starch nanocrystals thermal properties

Starch nanocrystals (SNC) are crystalline square-like platelet about 10 nm thick and 50-100 nm equivalent diameters. Depending on the botanic origin of starch these platelets show different features. The aim of the present study was (i) to assess the thermal stability of SNC in different processing conditions (i.e., excess water and dry) and (ii) to investigate the potential influence of botanic origin on thermal stability. The thermal properties of five types of starches (waxy maize, normal maize, high amylose maize, potato and wheat) and their corresponding SNC were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). SNC revealed two endothermic transitions. No correlation between melting temperature and botanic origin was found. However, a review of starch thermal properties allowed to postulate for the mechanism involved in SNC thermal transitions. It was also found that SNC can be used in wet processes below 100 °C and in dry processes below 150-200 °C to avoid melting.     

Preparation and characterization of mucilage polysaccharide for biomedical applications

In the present investigation, the polysaccharide/mucilage from waste of Abelmoscus esculentus by modification in hot extraction using two different solvents (Acetone, Methanol) were extracted, characterized and further compared with seaweed polysaccharide for their potential applications. The percentage yield, emulsifying capacity and swelling index of this mucilage were determined. The macro algae and okra waste, gave high % yield (22.2% and 8.6% respectively) and good emulsifying capacity (EC% = 52.38% and 54.76% respectively) with acetone, compared to methanol (11.3% and 0.28%; EC% = 50%) (PH = 7) while swelling index was greater with methanol than acetone extracts respectively. The infrared (I.R.) spectrum of the samples was recorded to investigate the chemical structure of mucilage. Thermal analysis of the mucilage was done with TGA (Thermal Gravimetric Analyzer) and DSC (Differential Scanning Calorimeter) which showed both okra and algal polysaccharide were thermostable hydrogels.     

Synthesis, characterization and optical properties of tin oxide nanoclusters prepared from a novel precursor via thermal decomposition route

As a new precursor, [bis(2-hydroxy-1-naphthaldehydato)tin(II)]; ([Sn(HNA)₂]), complex was used in thermal decomposition process for the synthesis of tin oxide (SnO₂) nanoclusters. The steric hindrance of the precursor raises the need of using co-surfactant, therefore oleylamine (C₁₈H₃₇N) was applied as the only surfactant of the reaction. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. Also the novel precursor was thermal treated in solid-state reaction in different temperature, 400, 500, and 600 °C. Synthesized tin dioxide nanoclusters with tetragonal phase, have average size of 1.5-4 nm. Finally, optical properties of the products were examined and investigated by photoluminescence spectra.     

The design and outdoor application of dye-sensitized solar cells

To upscale DSC size to commercial size, our group was involved in developing a commercial DSC panel, which could show the industrial way and prospect. The repeatable DSC module with the size of 150 mm × 200 mm and photoelectric conversion efficiency around 6% was reproduced in our laboratory. The DSC panel up to the size of 450 mm × 800 mm was fabricated. This is the high efficiency and industrial production design of a DSC panel, a primary power station with 500 W was installed on our roof for charging the battery. The study on the stability and performance of the DSC module, panel and future production are ongoing in our laboratory. In this article, we will report a systematic study in the test and the design from the single cell, the modules, to the panels, and our design of a 500 W primary DSC power station.     

Preparation and characterization of nano-hydroxyapatite/chitosan cross-linking composite membrane intended for tissue engineering

In this paper, a series of nano-hydroxyapatite(n-HA)/chitosan cross-linking composite membranes (n-HA; 0, 5, 10, 15, 20 and 30 wt%) were successfully developed by a simple casting/solvent evaporation method. n-HA with size about 20 nm in vertical diameter and about 100 nm in horizontal diameter was successfully synthesized by a hydro-thermal precipitation method, and then dispersed into chitosan/genipin solution with the aid of continuous ultrasound to develop n-HA/chitosan cross-linking composite membranes. The detailed characterizations including Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), water adsorption and tensile test were performed. With the analysis of FTIR spectra and TGA spectra, it suggested that there was existence of possible interactions between polymer and n-HA. Meanwhile, the n-HA content was greatly effected on the morphology as well as the tensile property of composite membrane. In vitro cytotoxicity test suggested that the developed n-HA/chitosan cross-linking composite membrane was non-cytotoxicity against L929 cells after 24 h's incubation might be suitable for further in vivo application.     

The single source preparation of rod-like mercury sulfide nanostructures via hydrothermal method

High-quality and high-yield rod-like HgS dendrites with cubic structure was synthesized by a wet chemical route, without using any surfactant and organic solvents at 180 °C for 5 h, by using Hg(NO₃)₂·H₂O and thioglycolic acid (TGA) as starting reagents. The obtained HgS with different morphologies and sized were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). The effects of reaction parameters, such as temperature, precursor concentration and reaction time on the morphology and particle size of products were investigated. Our experimental results showed that temperature reaction played key role in the final morphology of HgS. The morphology of HgS nanostructures could be changed from rod-like dendrites to nanoparticles by only decreased temperature reaction to 110 °C. In the present study the possible mechanism of HgS nanoparticles growth to dendrites in the aqueous solution was also discussed and the optical properties rod-like HgS dendrites were investigated by ultraviolet-visible (UV-Vis) spectroscopy.     

Synthesis and evaluation of physicochemical properties of cross-linked sago starch

Highly substituted sago starch phosphate was synthesized using POCl₃ as cross-linking reagent. Titrimetric and Fourier transform infra red (FT-IR) spectral analysis were used to characterize the substitution. Studying the different factors affecting the reaction parameters showed that the optimal conditions for starch phosphorylation were: 4 h reaction time and reagent concentration 1.5% (w/w). The physicochemical properties of cross-linked sago starch (CLSS) were done using Scanning electron micrograph (SEM), X-ray powder diffractometer (XRD and Thermogravimetric analysis (TGA). The results revealed that crystalline nature of native sago starch was transformed after cross-linking. TGA report exhibited higher thermal stability, which makes it suitable for various industrial applications. Swelling behavior showed high swelling at low temperature (30 and 60 °C) as compared to high temperature (90 °C).     

Pyrolytic characteristics of biomass acid hydrolysis residue rich in lignin

Pyrolytic characteristics of acid hydrolysis residue (AHR) of corncob and pinewood (CAHR, WAHR) were investigated using a thermo-gravimetric analyzer (TGA) and a self-designed pyrolysis apparatus. Gasification reactivity of CAHR char was then examined using TGA and X-ray diffractometer. Result of TGA showed that thermal degradation curves of AHR descended smoothly along with temperature increasing from 150 °C to 850 °C, while a “sharp mass loss stage” for original biomass feedstock (OBF) was observed. Char yield from AHR (42.64-30.35 wt.%) was found to be much greater than that from OBF (26.4-19.15 wt.%). In addition, gasification reactivity of CAHR char was lower than that of corncob char, and there was big difference in micro-crystallite structure. It was also found that CAHR char reactivity decreased with pyrolysis temperature, but increased with pyrolysis heating rate and gasification temperature at 850-950 °C. Furthermore, CAHR char reactivity performed better under steam atmosphere than under CO₂ atmosphere.     

Investigating the deep supercooling ability of an Alaskan beetle, Cucujus clavipes puniceus, via high throughput proteomics

Cucujus clavipes puniceus is a freeze avoiding beetle capable of surviving the long, extremely cold winters of the Interior of Alaska. Previous studies showed that some individuals typically supercool to mean values of approximately − 40 °C, with some individuals supercooling to as low as − 58 °C, but these non-deep supercooling (NDSC) individuals eventually freeze if temperatures drop below this. However, other larvae, especially if exposed to very cold temperatures, supercool even further. These deep supercooling (DSC) individuals do not freeze even if cooled to − 100 °C. In addition, the body water of the DSC larvae vitrifies (turns to a glass) at glass transition temperatures of − 58 to − 70 °C. This study examines the proteomes of DSC and NDSC larvae to assess proteins that may contribute to or inhibit the DSC trait. Using high throughput proteomics, we identified 138 proteins and 513 Gene Ontology categories in the DSC group and 104 proteins and 573 GO categories in the NDSC group. GO categories enriched in DSC include alcohol metabolic process, cellular component morphogenesis, monosaccharide metabolic process, regulation of biological quality, extracellular region, structural molecule activity, and antioxidant activity. Proteins unique to DSC include alpha casein precursor, alpha-actinin, vimentin, tropomyosin, beta-lactoglobulin, immunoglobulins, tubulin, cuticle proteins and endothelins.     

Preparation of crystalline starch nanoparticles using cold acid hydrolysis and ultrasonication

Waxy maize starch in an aqueous sulfuric acid solution (3.16 M, 14.7% solids) was hydrolyzed for 2–6 days, either isothermally at 40 °C or 4 °C, or at cycled temperatures of 4 and 40 °C (1 day each). The starch hydrolyzates were recovered as precipitates after centrifuging the dispersion (10,000 rpm, 10 min). The yield of starch hydrolyzates depended on the hydrolysis temperature and time, which varied from 6.8% to 78%. The starch hydrolyzed at 40 °C or 4/40 °C exhibited increased crystallinity determined by X-ray diffraction analysis, but melted in broader temperature range (from 60 °C to 110 °C). However, the starch hydrolyzed at 4 °C displayed the crystallinity and melting endotherm similar to those of native starch. The starch hydrolyzates recovered by centrifugation were re-dispersed in water (15% solids), and the dispersion was treated by an ultrasonic treatment (60% amplitude, 3 min). The ultrasonication effectively fragmented the starch hydrolyzates to nanoparticles. The hydrolyzates obtained after 6 days of hydrolysis were more resistant to the ultrasonication than those after 2 or 4 days, regardless of hydrolysis temperatures. The starch nanoparticles could be prepared with high yield (78%) and crystallinity by 4 °C hydrolysis for 6 days followed by ultrasonication. Scanning electron microscopy revealed that the starch nanoparticles had globular shapes with diameters ranging from 50 to 90 nm.     

Nanoparticle analysis of cancer cells by light transmission spectroscopy

We have measured the optical properties of cancer and normal whole cells and lysates using light transmission spectroscopy (LTS). LTS provides both the optical extinction coefficient in the wavelength range from 220 to 1100 nm and (by spectral inversion using a Mie model) the particle distribution density in the size range from 1 to 3000 nm. Our current work involves whole cells and lysates of cultured human oral cells in liquid suspension. We found systematic differences in the optical extinction between cancer and normal whole cells and lysates, which translate to different particle size distributions (PSDs) for these materials. Specifically, we found that cancer cells have distinctly lower concentrations of nanoparticles with diameters less than 100 nm and have higher concentrations of particles with diameters from 100 to 1000 nm—results that hold for both whole cells and lysates. We also found a power-law dependence of particle density with diameter over several orders of magnitude.     

Cellulose esters from waste cotton fabric via conventional and microwave heating

The esterification of cellulose from waste cotton fabric in a N,N-dimethylacetamide/lithium chloride solvent system was carried out using different types of fatty acid chloride including butyryl chloride, capryloyl chloride, and lauroyl chloride as esterifying agents, and N,N-dimethyl 1-4-aminopyridine as a catalyst under conventional and microwave activation. Microwave esterification was performed under 2.45 GHz with power varying from 90 to 450 W. The optimum conditions for esterification of cotton cellulose with various esterifying agents were investigated in terms of reaction time and temperature to attain appropriate %weight increase and degree of substitution of esterified-cellulose. The degree of substitution, functional group and chemical structure, and thermal stability of cellulose ester powder were characterized by ¹H NMR, FTIR, and TGA/SDTA analysis. Morphologies, crystallinity, and solubility of modified cellulose by two different heating methods were compared.     

Comparison of hydrolysis and HPLC/MS/MS procedure with ELISA assay for the determination of S-phenylmercapturic acid as a biomarker of benzene exposure in human urine

The present study compared three methods for the determination of S-phenylmercapturic acid (S-PMA), a metabolite of benzene, in human urine: a HPLC/MS/MS technique with two different sample treatments (strong and partial hydrolysis) and a commercial assay based on anti-S-PMA monoclonal antibodies with chemiluminescence detection. Biological monitoring was done on 126 volunteers and the results were compared for the three methods and also with benzene exposure levels (range <3.0–592.5 μg/m³). The correlation between environmental monitoring data and S-PMA levels in non-smokers (n = 73) was highly significant (p < 0.0001, Student's t-test) for both HPLC/MS/MS methods (r = 0.65 both for strong acidic hydrolysis of the urine and hydrolysis at pH 2) but not for the immunoassay, which overestimated the S-PMA levels by about 8 μg/g creatinine (creat.). Therefore the immunoassay is only useful as a semiquantitative screening test, but quantitative results need to be confirmed by a more accurate method like HPLC/MS/MS. The HPLC/MS/MS procedure with strong acid hydrolysis led to a recovery of S-PMA about double that using pH 2 hydrolysis, giving more accurate results. The difference between the results with the two methods makes it difficult to compare the strong acidic hydrolysis data with the ACGIH BEI value of 25 μg/g creat. since the BEI^® documentation is based on data collected in pH conditions that were not always controlled, which may underestimate the true S-PMA concentration. Besides, as levels of benzene exposure were high, smoking was not considered a confounding factor. The BEI for S-PMA in end of shift urine samples could be reconsidered when sufficient data are available from studies where the analyses are carried out in comparable conditions of hydrolysis and monitoring only non-smoking subjects.     

Calorimetric measurement of water transport and intracellular ice formation during freezing in cell suspensions

The current study presents a new and novel analysis of heat release signatures measured by a differential scanning calorimeter (DSC) associated with water transport (WT), intracellular ice formation (IIF) and extracellular ice formation (EIF). Correlative cryomicroscopy experiments were also performed to validate the DSC data. The DSC and cryomicroscopy experiments were performed on human dermal fibroblast cells (HDFs) at various cytocrit values (0–0.8) at various cooling rates (0.5–250 °C/min). A comparison of the cryomicroscopy experiments with the DSC analysis show reasonable agreement in the water transport (cellular dehydration) and IIF characteristics between both the techniques with the caveat that IIF measured by DSC lagged that measured by cryomicroscopy. This was ascribed to differences in the techniques (i.e. cell vs. bulk measurement) and the possibility that not all IIF is associated with visual darkening. High and low rates of 0.5 °C/min and 250 °C/min were chosen as HDFs did not exhibit significant IIF or WT at each of these extremes respectively. Analysis of post-thaw viability data suggested that 10 °C/min was the presumptive optimal cooling rate for HDFs and was independent of the cytocrit value. The ratio of measured heat values associated with IIF (q_IIF) to the total heat released from both IIF and water transport or from the total cell water content in the sample (q_CW) was also found to increase as the cooling rate was increased from 10 to 250 °C/min and was independent of the sample cytocrit value. Taken together, these observations suggest that the proposed analysis is capable of deconvolving water transport and IIF data from the measured DSC latent heat thermograms in cell suspensions during freezing.     

Packaging of a polymer by a viral capsid: the interplay between polymer length and capsid size

We report a study of the in vitro self-assembly of virus-like particles formed by the capsid protein of cowpea chlorotic mottle virus and the anionic polymer poly(styrene sulfonate) (PSS) for five molecular masses ranging from 400 kDa to 3.4 MDa. The goal is to explore the effect on capsid size of the competition between the preferred curvature of the protein and the molecular mass of the packaged cargo. The capsid size distribution for each polymer was unimodal, but two distinct sizes were observed: 22 nm for the lower molecular masses, jumping to 27 nm at a molecular mass of 2 MDa. A model is provided for the formation of the virus-like particles that accounts for both the PSS and capsid protein self-interactions and the interactions between the protein and PSS. Our study suggests that the size of the encapsidated polymer cargo is the deciding factor for the selection of one distinct capsid size from several possible sizes with the same inherent symmetry.     

Synthesis and characterization of curcumin loaded polymer/lipid based nanoparticles and evaluation of their antitumor effects on MCF-7 cells

Background

Hybrid materials are synthesized using hydrophilic polymer and lipids which ensure their long term systemic circulation through intravenous administration and enhance loading of hydrophobic drugs. The purpose of this study is to prepare, characterize and evaluate the in vitro efficacy of curcumin loaded poly-hydroxyethyl methacrylate/stearic acid nanoparticles in MCF-7.

Methods

C-PSA-NPs, prepared using the emulsification–solvent evaporation method were characterized by dynamic laser scattering, SEM, AFM, FT-IR, X-ray diffraction, and TGA. The in vitro release behavior was observed in PBS pH 7.4, the anticancer potential was analyzed by MTT assay, cell cycle and apoptosis studies were performed through flow cytometry. C-PSA-NPs drug localization and cancer cell morphological changes were analyzed in MCF-7 cell line.

Results

C-PSA-NPs exhibited the mean particle size in the range of 184 nm with no aggregation. The surface charge of the material was around − 29.3 mV. Thermal studies (TGA) and surface chemistry studies (FT-IR, XRD) showed the existence of drug curcumin in C-PSA-NPs. The MTT assay indicated higher anticancer properties and flow cytometry studies revealed that there were better apoptotic activity and maximum localization of C-PSA-NPs than curcumin.

Conclusions

Polymer lipid based drug delivery appeared as one of the advancements in drug delivery systems. Through the present study, a novel polymer lipid based nanocarrier delivery system loaded with curcumin was demonstrated as an effective and potential alternative method for tumor treatment in MCF-7 cell line.

General significance

C-PSA-NPs exhibited potent anticancer activity in MCF-7 cell line and it indicates that C-PSA-NPs are a suitable carrier for curcumin.     

Ozone gas affects physical and chemical properties of wheat (Triticum aestivum L.) starch

In this experiment, bread wheat flour and isolated wheat starch were treated with ozone gas (1,500 mg/kg at 2.5 L/min) for 45 min and 30 min, respectively. Starch was isolated from treated flour. Ozone treated starch and starch isolated from ozone treated flour had similar chemical and physical properties. Chemical analysis of starch isolates indicated depolymerization of high molecular weight amylopectins; with a subsequent increase in low molecular weight starch polymers as a result of starch hydrolysis. Ozone treatment resulted in elevated levels of carboxylic groups and decreased total carbohydrate content in amylopectin fractions. ¹H NMR results indicated formation of a keto group [(1→4)-3 keto] at the H-2 terminal (proton at C-2 position) and β-glucuronic acid at the H-1 terminal (proton at C-1 position). DSC transition temperatures and change in enthalpy were not affected by ozone treatment. Increased swelling power and RVA breakdown were observed in starch from ozone treated samples.     

Preparation and characterization of glycerol plasticized-pea starch/ZnO–carboxymethylcellulose sodium nanocomposites

Among natural polymers, starch is one of the most promising biodegradable materials because it is a renewable bioresource that is universally available and of low cost. However, the properties of starch-based materials are not satisfactory. One approach is the use of nano-filler as reinforcement for starch-based materials. In this paper, a nanocomposite is prepared using ZnO nanoparticles stabilized by carboxymethylcellulose sodium (CMC) as the filler in glycerol plasticized-pea starch (GPS) matrix by the casting process. According to the characterization of ZnO–CMC particles with Fourier transform infrared (FTIR), Ultraviolet–visible (UV–vis), X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetric analysis (TG), ZnO (about 60 wt%) is encapsulated with CMC (about 40 wt%) in ZnO–CMC particles with the size of about 30–40 nm. A low loading of ZnO–CMC particles can obviously improve the pasting viscosity, storage modulus, the glass transition temperature and UV absorbance of GPS/ZnO–CMC nanocomposites. When the ZnO–CMC contents vary from 0 to 5 wt%, the tensile yield strength increase from 3.94 MPa to 9.81 MPa, while the elongation at break reduce from 42.2% to 25.8%. The water vapor permeability decrease from 4.76 × 10⁻¹⁰ to 1.65 × 10⁻¹⁰ g m⁻¹ s⁻¹ Pa⁻¹.     

A facile one-pot synthesis of a fluorescent agarose-O-naphthylacetyl adduct with slow release properties

A microwave assisted facile synthesis of a fluorescent 6-O-naphthylacetyl agarose (NA-agarose) employing carbodiimide chemistry (dicyclohexylcarbodiimide/4-dimethylaminopyridine) has been described. NA-agarose was characterized by TGA, GPC, UV spectrophotometry, fluorescence spectroscopy, FT-IR, ¹H and ¹³C NMR spectra, exhibiting that in NA-agarose the naphthylacetyl group was attached to the backbone of the agarose polymer. The hydrolysis of NA-agarose in heterogeneous aqueous phase showed that the 1-naphthyl acetic acid (NAA), a plant growth regulator, got released in a controlled manner, the release rate being dependent on the hydrophilicity of the polymer adduct as well as on pH and temperature. The fluorescence emission (λ_max 332 nm) of NA-agarose (1 × 10⁻³ M) in ethylene glycol was significantly higher (ca. 82%) than that of the molar equivalent of NAA content in the product i.e. 0.08 mg in 1 × 10⁻³ M solution. The resulting polymer would be of potential utility as a sustained release plant growth regulator and sensory applications.