Biodegradable ionic matrix of variable internal polarity with grafted polymer

DETAILED DESCRIPTION What is claimed is: 1.
Particulate biodegradable matrix comprising: a hydrophilic and biodegradable ionic nucleus based on a cross-linked matrix of carbohydrates or polyols or polyamines, a hydrophilic polymeric layer, associated with the nucleus by ionic chemical interactions, functional surface molecules or polymers grafted on the hydrophilic polymeric layer by covalent bonds.
2.
The particulate biodegradable matrix according to claim 1, wherein the ionic nucleus is non-liquid and is grafted in the bulk of the core with lipophilic groups.
3.
The particulate matrix according to claim 1, wherein acid compounds are grafted on the matrix.
4.
The particulate matrix according to claim 1, wherein basic compounds are grafted on the matrix.
5.
The matrix according to claim 2, wherein lipophilic groups selected from fatty acids, polyoxyethyleneglycols, fatty amines, hydrophobic aminated acids, sterols, alkoxyethers, and mixtures thereof are grafted on the ionic matrix.
6.
The matrix according to claim 3, wherein the hydrophilic polymer layer is selected from natural and synthetic cationic polymers.
7.
The particulate matrix according to claim 4, wherein the hydrophilic polymer layer is selected from natural and synthetic anionic polymers.
8.
The matrix according to claim 1, wherein the surface polymers or molecules are bioadhesive or temporary relative to the reticuloendothelial system or have a tropism for a tissue or are activators of the immune system.
9.
The matrix according to claim 1, further comprising a component with biological activity selected from: antibodies, proteoglycanes, anticancer agents, antibiotics, antivirals, analogs of oligonucleotides and inhibitors of reverse transcriptase, antiproteases, insecticides and antifungals, oligonucleotides, ADN and elements of the genome, anesthetics and local anesthetics, benzocaine, vasoconstrictors, cardiotonics, digitoxin and its derivatives, vasodilators, diuretics and antidiuretics, prostaglandines, neuroleptics, antidepressants, hormones and derivatives, steroidal and non-steroidal anti-inflammatories, antihistamines, anti-allergic agents, antiseptics, diagnostic agents, vitamins, antioxidants, aminated acids and mineral salts, enzymes, hydroxy acids and essential oils, animal and vegetable cells, yeast, bacteria, and other micro-organisms, and molecules with activity for the absorption of UV radiation or of hydrating the epidermis