Nanostructures of pectin and its metal complexes

Abstract

Complexes with metal ions and nanostructures of pectin from Yalongoch lemon were prepared by precipitation. The structural organization and characteristics of the resulting nanostructures were studied by electron microscopy, rheology, and potentiometric titration. A growth-stimulating effect on cotton seeds was found for pectin nanostructures containing biogenic cations.Pectin (PC) is a water-soluble biologically active polymer that is widely used in medicine, the food industry, agriculture, etc.[1]. Its biological activity is clearly pronounced in the nanostructural form (certain type of supramolecular structures) or as nanostructured metal complexes [2]. The formation of one PC supramolecular structure or another depends greatly on the initial state and conformational rotation of its molecules in the solutions and the activity of the carboxyl and methoxyl groups in the chains. The preparation of nanostructures based on citric PC, which is used more widely than other types of PC for medical, food, and preventative purposes, is of great interest. Our goal was to study the formation of precipitated PC nanostructures and its complexes with metal ions (microelements) in addition to finding their biological activity.PC molecules typically are highly structured in solutions and can produce nanometer-sized particles depending on the precipitation method. Preliminary experiments showed that acetone was the most effective precipitant for producing PC nanostructures. Electron-microscopy images showed the formation of nanometer-sized PC particles in addition to dendritic crystals upon precipitation by acetone, especially for PC:acetone = 1:1.8 (Fig. 1). Increasing the amount of acetone in the mixture enlarged the crystallites and was accompanied in parallel by the formation of larger particles and dendritic structures.The formation of PC structures in solutions and their subsequent precipitation can be controlled using metal ions, which form polymer:metal complexes of various dimensions, including nanometer-sized ones. Changing the PC concentration favors the formation of certain particle shapes and sizes regardless of the type of Me 2+ . Electron-microscopy studies showed that nanostructures with particle sizes 10-50 nm were formed for all samples in the studied PC concentration range. Figure 2 shows that the solution with concentration C = 0.1% gave the most uniform structure with respect to distribution and size, i.e., the lower the solution concentration C < 0.1% was, the smaller were the dimensions of the nanoparticles. b c 5 m P 5 m P 5 m P a Fig. 1. Electron-microscopy images of PC precipitated by acetone for PC:acetone = 1:1.8 (a), 1:2.3 (b), and 1:2.6 (c).

Sugar‐Based Electroless Copper Deposition on Pectin‐Coated Alumina Microparticles

“…The key feature of pectin is the ability of the carboxyl groups to form strong complexes with the metal ions added to the dispersion, creating metal centers on the surface. [ 25 ] After the addition of the reducing agent, the first metal nuclei are formed on the surface, leading to a further deposition process in an autocatalytic manner. [ 18 ] In this work, we use pectin and STMP treatment as a sustainable and cost‐effective activation process compared to conventional methods.…”

“…We chose this biopolymer due to its water solubility and its capability to complex doubly positive charged metal ions. [ 25 ] To attach it to the ceramic particle surface (e.g., alumina particles) the pectin is modified using sodium trimetaphosphate (STMP), [ 26 ] which adds phosphate groups to the polymer.…”