WO2013046165A1

WO2013046165A1 - Use of functionalised nanosponges for the growth, conservation, protection and disinfection of vegetable organisms

Info

Publication number: WO2013046165A1
Application number: PCT/IB2012/055187
Authority: WO
Inventors: Carlo Maria Roggero; Stefano Di Carlo; Vander Tumiatti; Michela Tumiatti; Marco DE VECCHI; Valentina SCARIOT; Shubhen Kapila
Original assignee: Sea Marconi Technologies Di Vander Tumiatti S.A.S.
Priority date: 2011-09-30
Filing date: 2012-09-28
Publication date: 2013-04-04
Also published as: ITTO20110873A1

Abstract

The functionalised nanosponge is based upon a cross-linked cyclodextrin and contains at least one functionalising agent, such as a micro element, an active principle and/or a magnetic material. It is used for applications on vegetable organisms the growth, conservation, protection and/or disinfection of which is promoted. Such vegetable organisms include biomasses, fruit plants, ornamental plants, plants with oleaginous fruits or seeds, vegetables, cereals and algae.

Description

Use of functionalised nanosponges for the growth, conservation, protection and disinfection of vegetable organisms

This invention relates to the enhancement of the ^'functions for the growth, conservation, protection and disinfection of vegetable organisms.

^• State of the previous technique

The growth and the development of vegetable organisms are mainly correlatable to typical environmental factors such as the quantity and quality of water, carbon dioxide, light, temperature, pH, and the availability of nutrient elements and essential active principles. More specifically, an element is defined essential when its absence prevents the completion of the biological cycle of a vegetable organism. On the basis of their concentration in the vegetable tissues, the essential growth and conservation elements are divided into macro and micronutrients. The first ones (C, H, O, N, P, S, Ca, Mg, K, CI) are present with concentrations exceeding 1000 mg*kg^"1 and the second ones (Fe, Mn, Zn, Cu, B, Mo) with concentrations generally below 100 mg*kg^"1 (Marschner, 1995).

The main source of nutrients for vegetable organisms is the nutritive solution, in which the nutrients not only must be present, but also being found in a usable form, i.e. so that they can be taken by the organism itself and metabolised inside the tissues. To ensure the best growth and conservation conditions the macro and micronutrients must be present in a suitable and balanced concentration corresponding to the demand by the organism during the various phases of the life cycle. In fact, on one side the availability of the nutrients in the "nutritive solution" is very variable through time, on the other side the nutritional needs of the vegetable organism change during its growing phases.

The variations of the concentrations of the nutrients available for vegetable cultures is one of the most limiting factors for agricultural production, the production of biomasses in general and the one for algae. Resorting to an excessive use of fertilisers to overcome the nutritional deficiency is not, however, a sustainable solution both under the economical and environmental profile. Thus, it is evident the necessity of identifying and studying those mechanisms that at the "nutritive solution - vegetable organism" level can provide a decisive improvement, in qualitative and quantitative terms, of the agronomic use of nutritive elements.

Among the micro elements, the most known and studied element is undoubtedly Iron (FAO, 2006). Iron is an indispensable element for the mineral nutrition of the vegetable organisms, since it is an integral part of many enzymes which intervene in fundamental biological processes such as photosynthesis, respiration and DNA synthesis. Moreover, it performs an important role as co-factor of key enzymes involved in the oxide reduction, the splitting of peroxides, the symbiotic nitrogen fixation and in the synthesis of hormones controlling the development of the vegetable and its responses to variations of the environmental conditions. The importance of the Iron derives, most of all, from the fact that this element can exist in two different redox states: reduced (Fe2+) or oxidised (Fe3+). This characteristic allows its participation to numerous reactions involving the transfer of electrons (Zuchi, 2006).

The absorption of Iron in plants, in nature, occurs mainly through the roots. The roots are able to absorb the element only under a ferrous form (Fe II) or under a chelate form. When the environmental conditions are unfavourable (pH of the nutritive solution around or exceeding 7), the availability of the element for the plants is limited by the scarce solubility of the compounds in which it is present (oxides and hydroxides). Consequently, the plants, in order to satisfy their nutritional requirements, implement particular strategies that can ensure the absorption of sufficient quantities of Iron (Violante, 2002). With a deficiency of Iron, the dicotyledonous and monocotyledonous non-gramineae plants acidify the rhizosphere through a super activity of the H+-ATPasis, and the citrate anion, with chelating capacity passes from the cytoplasm of the root cells to the solution, providing the solu- bilisation of the Iron in the rhizosphere. The presence of a Fe(III)-citrate complex, as a solution, allows the roots to absorb the element (strategy I). The gramineae, with a different strategy (strategy II) cope with the deficiency of Iron by releasing in the rhizosphere, through specific channels or exocytosis, high amounts of non-proteinogenic amino acids, designated as siderophores, capable of chelating in a specific manner the FE(III) allowing the absorption of the complex (Romheld, 1987). These strategies of acquisition can result effective or ineffective on the basis of the single inter-actions plant-environment. In case of a missing absorption, the first detectable characteristic symptom in an "Iron - deficient" plant is the appearance of Iron chlorosis. Chlorosis is shown by the yellowing of the leaves caused by a decrement of the concentration of chlorophyll (Abadia and Abadia, 1993), which typically involves the youngest leaves, being Iron a lesser mobile element in the plant. Iron chlorosis appears since the Iron is necessary for the functionality of a series of proteins involved with the complex bio-synthetic process leading to the synthesis of chlorophyll (Pushnik and Miller, 1989).

The contribution of the element for the prevention or the cure of chlorosis can occur by radical and foliage application (Alvarez-Fernandez et al., 2004). On this subject, Iron chelates have achieved an increasingly decisive importance (Lucena, 2007). Chelation is a chemical reaction in which, normally, a metal ion is bonded to a reagent designated as chelant through more than one coordinate bond. The structure of the resulting compound constitutes a very stable complex having the central ion surrounded by the pincer-like chelant. A good chelant, under the vegetable nutrition point of view, protects the micro element from immobilisation holding it and maintaining it in solution and, at the same time, allows the roots/vegetable tissues to absorb it. An important condition is that these functions are occurring under variable environmental conditions, especially within a large range of pH and temperature.

The chelant molecules most used are: EDTA (ethylene-diamine-tetracetic acid), HEDTA (hydroxy-ethyl-diamine triacetate), DTP A (diethyl ene triamine peritaacetic acid), EDDHA (ethylene diamine-acetic acid). These molecules are proposed, depending upon the cases, for radical and/or foliar application (Alvarez-Fernandez et al., 2004; Borowski and Michalek, 2011).

There are three main critical factors correlated to the distribution into the environment of chelants, commonly used, depending upon the state of the previous technique.

"Heavy metals risk". Due to the high affinity of the known chelants for metals, the possibility exists to increment the bio-availability and the transfer, through the water bod- ies, of the heavy metals (extracting them and placing them in a solution) favouring the subsequent accumulation in the waters, in the soils and living organisms (Sillanpaa et al., 1997; Bucheli-Witschel and Egli, 2001 ; Oviedo and Rodriguez; 2003);

• "Biodegradability risk" The known chelants are characterised by a poor biodegrad- ability, fact that also prolongs their action through time (Yuan et al. 2006);

"Cytotoxicity risk". The known chelants, beyond certain levels, can become toxic for the vegetable organism (Wallace and Wallace, 1 83).

Thus there is a strong interests for new sustainable and intelligent solutions alternative to the current chelants of synthesis. The literature shows several inherent scientific works which, in particular, have verified the use of biodegradable organic acids, vegetable extracts and "Iron enriched biosolids" (Perez-Sanz et al., 2002; Marino, et al. 2004; Meers et al., 2004; Villen et al., 2007).

In the production of algae it has been surprisingly observed that bioelectric stimulation in conjunction with the synergic administration of Iron can positively influence the rate of growth. For example, by administering Iron via a chelant, such as EDTA, to a sample of Dunaliella salina in the presence of bio-electro stimulation obtained by the application of an electromagnetic field, included between 0 and 230 mT provided by an external generator (EMF), a growth peak is obtained up to 100% at 10 mT (W. Hunt, A. Zavalin; Int. J. Mol. Sci. 2009, 10, 4515-4558).

Technical problem and its solution

Thus, the object of this invention is to solve the criticalities pointed out here above in the state of the previous technique allowing the improvement and increment of the growth, the development and the conservation, as well as the protection and disinfection of vegetable organisms, in particular for what it concerns applications in open fields or greenhouses on fruit plants and ornamental plants, plants with oleaginous fruits or seeds, grapes, vegetables, cereals, in particular rice, biomasses, in particular algal and for the agro-energetic chain. For what algae are concerned it is possible to mention macro-algae, micro-algae, marine and fresh water algae, including diatoms (Bacilariophyta), green algae (Chlorophy- ceae), blue-green algae (Cyanophyceae), golden algae (Chrysophyceae), brown and/or red algae (for example Chiarella vulgaris, Hematococcus, Sticho coccus, Coccolithophorads, Scenedesmus dimorphus, Euglena gracilis, Dunalielia salina), in single or aggregated form.

This object is achieved thanks to the use claimed by one or more of the claims to follow.

In particular, in a new scenario of "Smart Agriculture" a new technique is made available based upon the use of functionalised nanosponges as complexing and carrying molecules , such as microelents like Iron, Zinc as well as other metals and organic and biologic active principles, such as for example enzymes (i.e. lypase, oxidoreductase, hydrolase).

Nanosponges can be used in aqueous dispersion for radical administration in hydroponic cultivation, foliar application or directly mixed with solid supports making the growth bed, strengthening the effects of the circulating nutrient solution. In this latter case and for dryness and/or lack of nutrients it is preferable to mix the nanosponges with particle vegetable carbon ("biochar" obtained by pyrolysis processes of selected biomasses), in order to create a surprising synergy between the nanosponges and the stable spongy structures of the biochar, capable of enhancing the absorption, holding and ensuring the gradual release of water, micronutrients, active biological substances, as well as creating a more favourable ambient for the development of useful microflora. Functionalised Nano Sponges (FNS) are macro molecules synthesised through specific crosslinking of the cyclodextrins and the trapping and/or encapsulation of microelements and/or active principles, functional for the applications required.

Cyclodextrins (CD) are natural cyclic oligosaccharides made up by a number of molecules of D-(+) glucopyrarioside variable from 6 to 8. The peculiarity of cyclodextrins is to have a truncated conical cavity where the available functional groups are arranged in a way that makes the surface hydrophilous and the inside hydrophobic. The lipophilic cavity allows the CDs to form stable inclusion complexes with organic molecules or biological active principles of an appropriate polarity and dimension. This peculiarity has been exploited to create products in different application fields such as pharmacopoeia, analytical chemistry and cosmetics. For example, cyclodextrins are used in pharmaceutical formulations to increment the dissolution velocity, the solubility and the stability of active principles; or as traps for smelly compounds in commercial products such as for example "Febreze" (Procter & Gamble).

Cyclodextrins, immobilised in a polymeric link do not loose their capacity of inclusion, whereas the inter-cyclodextrinic cavities can exhibit adsorbent and/or complexing capacity that, depending upon the type of crossliker chosen, make the polymer more specific for certain applications.

The previous documents US-5 608 015, US-4 681 934, US-7 922 783, WO-98/22 197, WO-2006/002 814 and IT2004MI00614 describe polymers based on cyclodextrins, without indicating a precise applicative functionalisation, or limiting it to the use in the analytical chemical, pharmaceutical or environmental field such as, for example, the purification of waters from persistent organic compounds.

It has been now surprisingly discovered that the FNS obtained trough a reticulation of cyclodextrins by means of diisocyanates and molecules containing carboxylic or hydroxil groups or their derivatives, in the presence of inorganic salts and/or active principles are capable of favouring the growth, the development, the protection and the disinfection of vegetable substance organisms, preventing physiopathologies due to nutritive deficiencies and/or changes in ambient conditions. Through the FNS, microelements, such as Iron and Zinc, are made more easily available with respect to the current alternatives based upon the chelants described here above.

FNS offer surprising sustainable solutions for "Smart Agriculture" (SA) in terms of Best Available Techniques (BAT) and Best Environmental Practices (BEP), in the production of vegetable organisms, capable of determining a better balance in technical, economic and environmental terms, characterised by lower production costs and reduced C0₂ emissions for the required life cycle (Life Cycle Analysis - LCA).

FNS provide the optimisation of the management of the mineral nutrition of vegetable organisms, for the global sustainable development in industrialised countries and in particular in the developing ones. The enhancement of the quantity and quality of agricultural production can be achieved through a better administration of micronutrients to the cultures and a higher absorption efficiency, even in marginal or meagre soils.

Synthesis of functionalised nanosponges (FNS)

The functionalised nanosponge (FNS) is realised through the synthesis of a polymer based upon the reticulation of the cyclodextrins (α, β, γ) and the encapsulation and/or impregnation of microelements and/or active principles. The microelements are salts of Fe, Zn, Mg, Cu, B and the active principles are substances useful for the growth, conservation, protection and disinfection of vegetable organisms, such as, for example: plant growth regulators (PGRs) (i; e. salicylic acid and its derivatives), phosphonates (i.e. aluminium tris (o-ethyl phosphonate), limonoids (i.e. azadirachtin) and triazoles (tebuconazole), natural or synthetic anti-ethylene preserving agents and disinfecting agents in general.

Moreover, it is possible to surprisingly grant electromagnetic properties to the FNS, through the encapsulation or impregnation, during the synthesis phase, of magnetic materials, preferably dispersed in the form of micro or nano powders, such as, for example: Iron- Silicon; Ferrites in general and preferably Ni-Zn and Mn-Zn Ferrites; (Sr/Ba) Fei₂0i9 Fer- rites; amorphous metals; Ni-Fe and Fe-Co alloys; Co-Cr alloys, Co:YFe₂0₃; Cr0₂; AlNiCo; Sm-Co compounds; Nd-Fe-B compounds. In this latter case FNS can create synergies with permanent or pulsating electromagnetic fields (EMFs) generated by external devices operating in the ranges 0.01-1000 mT and 10 Hz - 2000 kHz, originating programmed cycles of electro-bio stimulation that bring a considerable increment in the growth rate of vegetable organisms. ·

FNS are obtained according to two different operational synthesis processes. The synthesis of FNS occurs under shaking conditions inside a reactor at ambient pressure and it could require the heating of the mixture formed by the reacting substances up to a 70° C temperature. In relation to the type of reaction and application the formulation can be enhanced by using a high efficiency mixing device (homogenisers) or an ultrasound dispersion or mi- cronisation device. In relation with the type of application, the molar ratio between the reacting molecules can be changed. In fact, depending upon the type of functionalisation required it can be necessary to have inter-cyclodextrinic cavities of appropriate dimensions which diminish with the increment of the ration between the stoichiometric concentrations between reticulants and cyclodextrins.

The syntheses of FNS do not generate by-products different from water thus they are better with respect to the inventions relative to nanosponges synthesised using other reticulants such as, for example, diphenyl carbonate, compound that generates the formation of a toxic, corrosive and mutagenic by-product difficult to be removed such as phenol. This characteristic makes the purification procedures of the FNS simpler, more effective and re- peatable, providing production lots with a constant and guaranteed quality.

The synthesis of the FNS is more flexible and economic with respect to those of the patent applications WO 2006/002814, WO 2009/149883 and IT2004MI00614, since it uses reagents more easily available, cheaper (the industrial cost of a diisocyanate with respect to a pyromellitic anhydride is 6 or 7 times lower), more reactive and easily purifiable, which do not generate dangerous by-products that can remain permanently encapsulated in the cyclodextrinic cavity leading to a defacto creation of an impure final product potentially critical for its applications.

Moreover, the synthesis of the FNS has a higher yield, exceeding 95 %, thanks to the high reactivity of the reticulants and to the easy removal of the water generated (differently to, for example, phenol which has a very high boiling point and, furthermore it can be encapsulated in the polymeric link "molecular imprinting" - or in the cyclodextrinic cavity).

The FNS so obtained, with respect to the products existing on the market, such as for example DTPA provide a more effective and prolonged bio-availability of the microelements. The results of the application show that the FNS are more effective with respect to DTPA in terms of growth, development and protection of vegetable organisms. The results compared and better detailed in the examples to follow, emphasise:

I) A higher growth expressed as quantity of dry and fresh weight of the leaves, with increment up to 20% and more, in the case of FNS loaded with ferrous sulphate (Fell) tested on corn in hydroponic solution and compared with solutions containing the same amount of Iron under the form of DTPA-Fe (III) under the same growth conditions (fig. 2 and 3).

II) A better development and health of the vegetable organism expressed as SPAD index (indirect measurement of the quantity of chlorophyll in the vegetable tissues and the grade of chlorosis of the plant), with an increment up to 22 % and more, in the case of FNS loaded with ferrous sulphate (Fell) tested on corn in hydroponic solution and compared with solutions containing the same amount of Iron under the form of DTPA-Fe (III) under the same growth conditions (fig. 4).

III) A higher biodegradability of the FNS with respect to DTP A, thanks to the cyclo- dextrinic component, natural derivative of starch.

IV) A negligible phytotoxic effect of the FNS with respect to DTPA.

V) A better protection of the microelements and the active principles by the FNS which, being water insoluble, protect the encapsulated or impregnated microelements and the active principles from washing away phenomena and prevent critical inter-actions with the surrounding environmental matrices.

It has been surprisingly observed that the FNS, loaded with microelements, reduced to an appropriate granulometry and suspended in hydroponic solution, are capable of being absorbed by the plant entering the lymphatic ducts, without causing phytotoxic effects. This behaviour has been observed by applying the FNS, suspended in an appropriate wetting/sticking solution (i. e. alkoxilates) on leaves of corn plants.

First synthesis process of the FNS (impregnation of the functionalising agent)

In the first process there are two distinct phases (see Example 1 to follow).

The first phase consists in the preparation of a low-molecular weight pre-polymer. The pre- polymer is obtained through the reaction in solution of water, n-methylpyrrolidone, di- methylformamide, dimethyl sulfoxide between:

I) cross-linking and co-functionalisers molecules containing acids or hydrox- yls or acid derivatives groups (typically acetylsalicylic acid, citric acid, maleic anhydride, taurine, medium-low molecular weight polyethylene glycol, hanydride 1,2,4- benzene tri- " carboxylic);

II) cross-linking molecules carrying isocyanate groups chosen among lysine- diisocyanate (LDI), hexamethylene diisocyanate (HDI), methylenediphenyl diisocyanate (MDI), Toluene diisocyanate (TDI).

The second phase consists in the reaction in a solution, preferably of water, n-methyl-2- · pyrrolidone, dimethylformamide, dimethyl sulfoxide, between:

a. the pre-polymer;

b. the cyclodextrins (α, β, γ)

c. the reticulant molecules that carry isocyanate groups chosen among lysine- diisocyanate (LDI), hexamethylene diisocyanate (HDI), methylenediphenyl diisocyanate (MDI), toluene diisocyanate (TDI);

d. the functionalising agents for the applications required such as salts of micro elements and/or active principles.

Second synthesis process of the FNS (encapsulation of the element and/or active principle)

In the second process, the FNS (cfr. Example 2 to follow) are obtained by dry-mixing the following substances:

a. the cyclodextrins (α, β, γ);

b. the cross-linking agents containing acid or hydroxyls or acid derivatives groups (typically acetylsalicylic acid, citric acid, maleic anhydride, taurine, medium-low molecular weight polyethylene glycol, hanydride 1 ,2,4- benzene tricarboxylic) or isocyanate groups chosen among lysine-diisocyanate (LDI), methylenediphenyl diisocyanate (MDI), toluene diisocyanate (TDI). methylene diisocyanate (HDI); c. the functionalising agents for the applications required such as salts of micro elements and/or active principles.

The mixture obtained is dispersed in solvents preferably chosen among water or other solvents, such as n-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide. Purification process of the FNS

The FNS obtained following the first or second process described above are subjected to a purification process. This process consists essentially in the solid-liquid extraction using appropriate solvents (preferably acetone or ethyl ether to eliminate organic compounds that did not react and water to eliminate the residual cyclodextrins and solvents). The extraction occurs preferably in the same synthesis reactor, with shaking, at the boiling temperature of the solvent with subsequent distillation and re-condensation of the same inside the reactor (closed loop). The process continues until the residual concentration of reagents and solvents, compatible with the type of application^ achieved.

Micronisation and sterilisation phase of the FNS

The purified and dried FNS are micronised to the level of granulometry required by the application through an appropriate mill and/or ultrasound device. In case it is required, the single lots are sent to the sterilisation and immediately packaged to ensure the required quality level.

Preparation of stable suspensions of FNS

When required, the FNS micronised to the appropriate level of granulometry are dispersed in different typologies of liquids for hydroponic and foliar administration, by wetting/sticking agents, such as alkoxilates, or on solid substrate.

Examples

The following not-limiting examples, further illustrate the application of the process of the invention also with the help of the illustrative tables enclosed, in which:

Figure 1 is a diagram showing the SPAD index measured on corn plants cultivated in solution containing or not FNS.

Figure 2 is a diagram showing the increment of the dry weights of leaves of corn induced by the administration of Iron by means of FNS with respect to a comparison commercial product.

Figure 3 is a diagram showing the increment of the fresh weights of leaves of corn induced by the administration of Iron tlirough FNS with respect to a comparison commercial product.

Figure 4 is a diagram showing the SPAD index induced by the administration of Iron by means of FNS with respect to a comparison commercial product.

Figure 5 is a diagram showing the increment of the dry weights of roots of gibasis induced by the administration of Iron by means of FNS with respect to a comparison commercial product and

Figure 6 is a photograph pointing out the re-greening effects of products by the leaves administration of a stable watery suspension of FNS of example 2.

Example 1

This is a typical example of nanosponges functionalised by Iron impregnation.

20 g of β-CD and 17.6 g of MDI are mixed and transferred little by little in a reaction container holding about 50 g of n-methylpyrrolidone (NMP) kept under shaking.

The mixture becomes increasingly thicker until it fully solidifies with a white-yellow colour. The temperature increases up to 60° C and slowly starts to decrease; once the reticulation is completed, the solid is removed from the container and crushed.

A soxhlet purification with acetone is carried out.

Then the nanosponge is dipped into an acid solution with a known concentration of Iron sulphate for a few hours.^' The so obtained suspension is then dried.

The FNS is micronised by an appropriate steel ball mill obtaining a granulometry profile in the range between 1 and 5 μηι.

Example 2 This is a typical example of functionalised nanosponges by means of the encapsulation of Iron.

20 g of β-CD and 17.6 g of MDI and 1 1 g of anhydrous Iron sulphate are mixed and transferred little by little in a reaction container holding about 70 g of n-methylpyrrolidone (NMP) kept under shaking.

The mixture becomes increasingly thicker until it fully solidifies with a white-greenish colour. The temperature increases up to 60° C and slowly starts to decrease; once the reticulation is completed, the solid is removed from the container and crushed.

A soxhlet purification with acetone is carried out.

Example 3

This is a typical example of functionalised nanosponges by means of the encapsulation of Zinc.

22.6 g of β-CD and 20 g of MDI and 9 g of anhydrous Zinc sulphate are mixed and transferred little by little in a reaction container holding about 50 g of NMP kept under shaking.

The mixture becomes increasingly thicker until it fully solidifies with a white-greenish colour. The temperature increases up to 60° C and slowly starts to decrease; once the reticulation is completed, the solid is removed from the container and crushed. A soxhlet purification with acetone is carried out.

The FNS is macronised by an appropriate steel ball mill obtaining a granulometry profile in the range between 1 and 5 μιη. Example 4

This is a typical example of functionalised nanosponges by means of the encapsulation of Iron in a different form with respect to the previous examples.

5.2 g of β-CD and 4.2 g of MDI and 4.1 g of anhydrous Iron citrate are mixed and transferred little by little into a polypropylene container holding about 30 g of (NMP) kept under magnetic shaking. After about 10 minutes 2.2 g of MDI are added. Once the addition is completed, the magnetic anchor is removed.

In a few minutes the reaction starts and the mixture becomes increasingly thicker until it fully solidifies with a white-orange colour. The temperature increases up to 60° C and slowly starts to decrease; after about 2 hours it stabilises at 25° C. Then, the solid is removed and crushed into a powder.

A soxhlet purification with acetone is carried out.

Example 5

This is a typical example of functionalised nanosponges by means of the reaction and encapsulation of a growth and protection active principle.

5.0 g of MDI with 2.7 g of salicylic acid are mixed into 10 ml of n-methylpyrrolidone warming it to 60° C for 2 hours in a propylene container. Then 22.7 g of CD, 15 g of MDI are added and 20 g of NMP more, accurately mixing. Wait for 1.5 hour.

Then the solid is removed and crushed into a powder.

A soxhlet purification with acetone is carried out.

Example 6 This is a typical example of application of FNS as is, emphasising the non-toxicity of an empty nanosponge, thus its aptitude to be used as vector of functionalising agents. An aliquot of FNS, obtained as described in example 1, is used as is in the hydroponic cultivation of corn plants. At the same time, other corn plants are arranged in hydroponic cultivation with a solution without FNS. The growth of the plants and the connected evaluation parameters are monitored for several days. Figure 1 shows the relevant results expressed in terms of SPAD index. A higher value of the SPAD index is surprisingly inferred in the case of plants cultivated in solution containing FNS as is in comparison with plants cultivated with solution without FNS. Moreover, no phytotoxic effects are found like instead it occurs in the case the DTP A is used even in lower concentrations.

Example 7

This is an example of application of impregnated FNS in the hydroponic cultivation of corn.

An aliquot of the FNS obtained as described in example 1 is used as a compound carrying Iron together with other nutrient salts for the hydroponic cultivation of plants of corn. At the same time, other corn plants are cultivated under hydroponic conditions with solution containing the same amount of Iron under the form of Iron chelate with DTPA. The growth of the plants and the connected evaluation parameters are monitored for several days. Figures from 2 through 4 show the results relative to the weight of fresh biomass, dried bio- mass and the SPAD index. It is inferred that the FNS are much more effective with respect to the DTPA in making the plant growing and in keeping the chlorophyll index high.

Example 8

This is an example of application of encapsulated FNS in the hydroponic cultivation of corn.

An aliquot of the FNS obtained as described in example 2 is used as a compound carrying Iron together with other nutrient salts for the hydroponic cultivation of plants of corn. At the same time, other corn plants are cultivated under hydroponic conditions with solution containing the same amount of Iron under the form of Iron chelate with DTPA. The growth of the plants and the connected evaluation parameters are monitored for several days. Figures from 2 through 4 show the relevant results.

Example 9

This is an example of application of impregnated FNS in the hydroponic cultivation of gi- basis.

An aliquot of the FNS obtained as described in example 1 is used as a compound carrying Iron together with other nutrient salts for the hydroponic cultivation of plants of gibasis. At the same time, other gibasis plants are cultivated under hydroponic conditions with solution containing the same amount of Iron under the form of Iron chelate with DTPA or ferrous sulphate as is. The growth of the plants and the connected evaluation parameters are monitored for several days. Figure 5 shows the increment of the weights of the roots.

Example 10

This is an example of application of FNS encapsulated with active principle in the hydroponic cultivation of gibasis.

An aliquot of the FNS obtained as described in example 4 is used as a compound carrying Iron together with other nutrient salts for the hydroponic cultivation of plants of gibasis. At the same time, other gibasis plants are cultivated under hydroponic conditions with solution containing the same amount of Iron under the form of Iron chelate with DTPA or ferrous sulphate as is. The growth of the plants and the connected evaluation parameters are monitored for several days. From this monitoring it is inferred the higher capacity of the FNS with respect to the commercial product, to increment the growth of leaves and keep the SPAD index at higher values.

Example 1 1 This is an example of application of FNS encapsulated and carried by means of a bonding agent, in the foliar administration of iron on corn.

An aliquot of the functionalised nanosponge obtained as described in example 2 is used as carrying compound of Iron together with other nutrient salts in the foliar dressing of corn plants subject to a nutrition condition without Iron. Once the desired level of chlorosis was achieved, the leaves of the corn plants have been treated with a watery suspension of FNS of example 1 together with a cling agent, such as an alkoxilate. The formation of green spots (cfr. Fig. 6) indicates the capacity of the FNS to carry Iron inside the leaf, reinstating the original capacities for photosynthesis.

Naturally, being understood the principle of the invention, the details for the implementation and the embodiments can greatly vary with respect to what herein described purely as a simplified example, without, for this reason, getting out from the claimed scope.

Claims

1. Use of a functionalised nanosponge based upon a cross-linked cyclodextrin and containing at least one functionalising agent, such as a microelement, an active principle and/or a magnetic material, for the application on vegetable organisms of which the growth, conservation, protection and/or disinfection is promoted.

2. Use according to claim 1, wherein said vegetable organisms include biomasses, fruit plants, ornamental plants, plants with oleaginous fruits or seeds, vegetables, cereals and algae.

3. Use according to anyone of the previous claims wherein said cross-linked cyclodextrin is used in watery dispersion for hydroponic cultivations or foliar dressing or directly mixed with solid supports making up the growth bed, such as "biochar" obtained by the pyrolysis process of selected biomasses.

4. Use according to anyone of the previous claims wherein said cross-linked cyclodextrin is a polymer obtainable by the synthesis of cyclodextrinic units type α, β or γ and at least one reticulant agent having two or more reactive groups, preferably in a molar ratio from 0.5 to 0.05.

5. Use according to claim 4, wherein said cross-linking agent presents carboxylic or hydroxil groups or their derivatives, such as acetylsalicylic acid, citric acid, maleic anhydride, taurine, polyethylene glycol with molecular weight in the range between 350 and 10000, 1,2,4- benzene tricarboxylic anhydride.

6. ^' Use according to claim 4 or 5, wherein said cross-linking agent presents isocyanate groups such as lysine-diisocyanate (LDI), hexamethylene diisocyanate (HDI), methylene- diphenyl diisocyanate (MDI), toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI).

7. Use according to anyone of the previous claims, wherein said microelement is a salt of a metal such as Fe, Mn, Zn, Cu, B and Mo, and said active principle is a plant hormone, such as salicylic acid and its derivatives, a phosphonate such as aluminium tris (o-ethyl phosphonate), a limonoid such as azadirachtin, a triazole such as tebuconazole or an enzyme such as lyase, oxidoreductase or hydrolase.

8. Use according to anyone of the previous claims, wherein said functionalising agent is a magnetic material, preferably dispersed in the form of micro- or nano-powders chosen in the group consisting of: Iron-Silicon, Ferrites, preferably Ni-Zn, Mn-Zn Ferrites and (Sr/Ba) Fei₂0i9 Ferrites, amorphous .metals, Ni-Fe and Fe-Co alloys, Co-Cr alloys, Co:yFe₂0_3i Cr0_2> Alnico; Sm-Co compounds, and Nd-Fe-B compounds and said vegetable organisms are subject to the action of an external electromagnetic field.

9. Use according to anyone of the previous claims, wherein the encapsulation and impregnation of the cross-linked cyclodextrin with the functionalising agent in a weight ratio in the range between 0.1 and 20 % are entirely made under dry conditions, or at first humid ones, making the nanosponge absorbing a solution of the functionalising agent, and then drying it.

10. Use according to anyone of the previous claims, wherein said nanosponge is micro- nised into particles with dimensions in the range between 0.1 and 500 μηι, which are suspended in a solution suitable for radical or foliar administration or associated with a solid substrate.