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PREPARATION OF GOLD NANOPARTICLES STABILIZED BY CHITOSAN USING IRRADIATION AND SONICATION METHODS

100%

Czechowska-Biskup R., Rokita B., Ulański P., Rosiak J. M.

Progress on Chemistry and Application of Chitin and its Derivatives

2015

vol. 20

18-33

Gold nanoparticles (AuNPs) were synthesized, in the absence of any reducing agent, using ionizing radiation or ultrasound in aqueous solutions of chloroauric acid (HAuCl4). Chitosan (average molecular weight 158 kDa, degree of deacetylation 90 %) was used as a stabilizing agent. Both techniques yielded AuNPs which were stable in solution at RT for at least 3 months after synthesis. UV-Vis spectroscopy was used to follow substrate decay, nanoparticles formation, size of the gold core and particles stability. Hydrodynamic radii and polydispersion of the chitozan-stabilized AuNPs (i.e. the whole core-shell nanoparticles) were determined by dynamic light scattering. Zeta potential measurements were performed to assess the surface charge and stability of the particles. Influence of synthesis parameters and presence of isopropanol on the formation and properties of the products have been described and reaction mechanisms have been discussed. Radiation and sonochemical methods are demonstrated to be very efficient, fast and easy-to-control methods of synthesizing gold nanoparticles, leaving behind no unreacted reducing agent or unwanted side products, while stabilization by chitosan provides AuNPs with excellent stability and long shelf life.

DETERMINATION OF DEGREE OF DEACETYLATION OF CHITOSAN - COMPARISION OF METHODS

88%

Czechowska-Biskup R., Jarosińska D., Rokita B., Ulański P., Rosiak J. M.

Progress on Chemistry and Application of Chitin and its Derivatives

2012

vol. 17

5 - 20

Degree of deacetylation (DD) is one of the main parameters characterizing chitosan. The most precise measurements of DD require sophisticated equipment (NMR spectrometer), not available at many laboratories worldwide working on chitosan. There is a need for low-cost, simple, yet sturdy and reliable methods and procedures for DD determination. The aim of this work was to test and compare – on the same set of chitosan samples - a few of the existing analytical techniques and provide recommendation for selecting DD determination methods. Tests were performed on four chitosans of nominal DD in the range 70 - 95%. Three different methods of titration, two different methods of spectroscopy UV / Vis and infrared spectroscopy using various calculation approaches were used. The results are summarized and compared with values obtained by 1H NMR, considered as the reference method. Moreover, evaluation of the ease of performance and availability of reagents in the given methods was performed. On that basis, recommendations for selection of DD determination methods were formulated.

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2 Progress on Chemistry and Application of Chitin and its Derivatives

1 2015

1 2012

2 Czechowska-Biskup R.

2 Rokita B.

2 Rosiak J. M.

2 Ulański P.

1 Jarosińska D.

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PREPARATION OF GOLD NANOPARTICLES STABILIZED BY CHITOSAN USING IRRADIATION AND SONICATION METHODS

DETERMINATION OF DEGREE OF DEACETYLATION OF CHITOSAN - COMPARISION OF METHODS