A particle comprising: (i) an inorganic core comprising silica or magnetite; and (ii) polymeric or oligomeric anti-microbial active unit chemically bound to the core directly or indirectly (via a third linker) to the core; wherein the polymeric or oligomeric anti-microbial active unit comprises more than one monomeric units comprising an anti-microbial active group; wherein the number of the anti-microbial active groups per each anti-microbial active unit is between 2-200; and wherein said particle is represented by the following structure: wherein L 1 is a bond or a first linker; L 2 is a second linker; L 3 is a bond or a third linker; R 1 and R 1 ' are each independently alkyl, terpenoid, cycloalkyl, aryl, heterocycle, alkenyl, alkynyl or any combination thereof; R 2 and R 2 ' are each independently alkyl, terpenoid, cycloalkyl, aryl, heterocycle, alkenyl, alkynyl or any combination thereof; R 3 and R 3 ' are each independently not present, hydrogen, alkyl, terpenoid moiety, cycloalkyl, aryl, heterocycle, alkenyl or alkynyl; wherein if R 3 or R 3 ' is nothing the nitrogen is not charged; X 1 and X 2 is each independently a bond, alkylene, alkenylene, or alkynylene; p defines the surface density of anti-microbial active units per one sq nm (nm 2) of the core surface, wherein said density is of between 0.01-30 anti-microbial active groups per one sq nm (nm 2) of the core surface of the particle; n 1 is each independently an integer between 0 to 200; n 2 is each independently an integer between 0 to 200; wherein n 1 +n 2 ≥2; m is an integer between 1 to 200 and the repeating unit is the same or different; said first, second and third linkers are independently a C 1 to C 18 alkylene, alkenylene, alkynelene, arylene or conjugated alkylene, optionally substituted with one or more functional groups including phosphate, phosphonate, siloxane, silane, ether acetal, amide, amine, anhydride, ester or an aromatic ring; and said alkyl is unsubstituted or substituted by a halogen, haloalkyl, hydroxyl, alkoxy, carbonyl, amido, alkylamido, dialkylamido, cyano, nitro, CO 2 H, amino, alkylamino, dialkylamino, carboxyl, thio and/or thioalkyl; and said surface density is measured via the spectrophotometric methods disclosed in Example 6 of the description. (i) an inorganic core comprising silica or magnetite; and (ii) polymeric or oligomeric anti-microbial active unit chemically bound to the core directly or indirectly (via a third linker) to the core; wherein the polymeric or oligomeric anti-microbial active unit comprises more than one monomeric units comprising an anti-microbial active group; wherein the number of the anti-microbial active groups per each anti-microbial active unit is between 2-200; and wherein said particle is represented by the following structure: wherein L 1 is a bond or a first linker; L 2 is a second linker; L 3 is a bond or a third linker; R 1 and R 1 ' are each independently alkyl, terpenoid, cycloalkyl, aryl, heterocycle, alkenyl, alkynyl or any combination thereof; R 2 and R 2 ' are each independently alkyl, terpenoid, cycloalkyl, aryl, heterocycle, alkenyl, alkynyl or any combination thereof; R 3 and R 3 ' are each independently not present, hydrogen, alkyl, terpenoid moiety, cycloalkyl, aryl, heterocycle, alkenyl or alkynyl; wherein if R 3 or R 3 ' is nothing the nitrogen is not charged; X 1 and X 2 is each independently a bond, alkylene, alkenylene, or alkynylene; p defines the surface density of anti-microbial active units per one sq nm (nm 2) of the core surface, wherein said density is of between 0.01-30 anti-microbial active groups per one sq nm (nm 2) of the core surface of the particle; n 1 is each independently an integer between 0 to 200; n 2 is each independently an integer between 0 to 200; wherein n 1 +n 2 ≥2; m is an integer between 1 to 200 and the repeating unit is the same or different; said first, second and third linkers are independently a C 1 to C 18 alkylene, alkenylene, alkynelene, arylene or conjugated alkylene, optionally substituted with one or more functional groups including phosphate, phosphonate, siloxane, silane, ether acetal, amide, amine, anhydride, ester or an aromatic ring; and said alkyl is unsubstituted or substituted by a halogen, haloalkyl, hydroxyl, alkoxy, carbonyl, amido, alkylamido, dialkylamido, cyano, nitro, CO 2 H, amino, alkylamino, dialkylamino, carboxyl, thio and/or thioalkyl; and said surface density is measured via the spectrophotometric methods disclosed in Example 6 of the description.