determination of phytohormone using layered double hydroxide nanostructures

Plant hormones are involved in several stages of plant growth and development, it is essential for plant defense [1]. until recently it was assumed that the main plant growth processes were controlled by 5 types of phytohormones, namely the auxins, cytokinins, gibberellins, abscisic acid, and ethylene. gibberellins (gas) are a large family of structurally related diterpenoid acids that occur in green plants and some microorganisms. gibberellin 3 (ga) is an important member of gibberellin family and acts as a natural plant growth hormone, controlling many developmental processes such as the induction of hydrolytic enzyme activity during seed germination, stem elongation, induction of flowering, improvement of crop yield, overcoming dwarfism, elimination of dormancy, sex expression, enzyme induction and leaf and fruit senescence, etc [2-5]. due to these properties, this hormone (ga) is of great importance in agriculture, nurseries, tissue culture, tea garden, viticulture, acceleration of germination in the brewery industry, etc [6-8]. this is due to its fast and strong effects at low concentrations (μg) on the above processes, this will led to obtaining better harvests in the agriculture area and by extension improving the food industry. in addition, ga was also used in a variety of activities related to research work and pharmacological applications [5]. gibberellins are distributed widely through the plant kingdom where they play an important role in plant growth and development. they have also been isolated from fungi and bacteria. [9-11].various methods such as high performance liquid chromatography-tandem mass spectrometry (hplc-ms) [12,13] and immunoassays [14] have been developed for gibberellin 3 detection. but hplc-ms has some deficiencies such as costly equipment and tedious and time-consuming procedures. the immunoassay exhibits relatively low detection limits. layered double hydroxides (ldhs), well-known as anionic clays or hydrotalcite-like compounds, are a large class of natural and synthetic materials, which have received considerable attention in recent years due to their promising applications in many fields, such as in catalysts and catalyst supports, adsorbents, separation materials, additives in plastics, and biological and pharmaceutical materials [15-18]. ldhs are represented by the general formula [m2+ 1-xm3+ x(oh)2] (ax/n n-) . mh2o, wherem2+ is a divalent cation (mg2+, zn2+, cu2+, ni2+, co2+, etc.), m3+ is a trivalent cation (al3+, fe3+, cr3+, etc.), and an- is an interlayer anion (co3 2-, so4 2-, no3 -, cl-, oh-, etc.); x is a ratio between di- and trivalent cations with various values between 0.2 and 0.33.21,22 the structure consists of brucite-like layers built up from edge-sharing m(oh)6 octahedra. interestingly, a partial and isostructural m2+ to m3+ substitution would induce a positive charge for these layers, balanced with the negatively charged interlayer region containing anions and water molecules [19]. this remarkable structure feature allows ldhs to have a powerful ability to capture organic and/or inorganic anions in aqueous solutions.thus, a simple, highly sensitive, and selective method for trace gibberellin 3 detection is highly desirable. in this work, using layered double hydroxides and gce, a cheap, comfortable, high sensitivity, high selectivity sensor, and a very good detection limit were obtained. using cyclic voltammetric technique, layered double hydroxides were placed on gce, and then used to determine gibberellin 3 in agricultural fertilizer samples.in this work, layerd double hydroxide nanostructures were synthesized using microwave method. layerd double hydroxide nanostructures were investigated as environmentally friendly, inexpensive with adjustable composition by scanning electron microscopy and used for electrode modification. these nanostructures, as a new modifier, were able to quantify small amounts of an agricultural phytohormone called gibberellin 3 using a sensitive differential pulse voltammetry technique.