A kit comprising uncoated magnetic nanoparticle entrapped in a matrix of protein cross-linked with epichlorohydrin, wherein the MNP is entrapped by a method comprising incubating the protein with magnetic nanoparticles in a binding buffer having pH ranging from 6-9 along with epichlorohydrin at a temperature of about 4°C to 30°C, with the optional supplementation of salts, and wherein the MNP is entrapped in a ratio ranging from about 1:5 to 1:0.25 and has a particle size in the range of 1 to 100nm, wherein: the kit is a diagnostic kit for immobilization, purification and identification of IgG, Fab fragments or single chain variants, functional proteins from biological samples comprising: (i) 25μgm to 10mg magnetic nanoparticle entrapped in a matrix of cross-linked protein having affinity to IgG/Fab fragments in 5mM Sodium phosphate buffer, pH 8.0; (ii) 25ml washing buffer, i.e. IX phosphate buffer pH 8; (iii) 50ml IgG/Fab fragment elution buffer, i.e. an acidic buffer comprising phosphate buffer pH 2.8; or glycine, pH 2; or L-Arginine, pH 3; (iv) 2ml neutralizing buffer, i.e. 1M Tris, pH 9.0; (v) a catalogue comprising instructions and parameters relating to use of the kit; or the kit is an immunoprecipitation kit for the detection of an immunogen or antigenic proteins comprising (i) 25μg to 10 mg magnetic nanoparticle entrapped in a matrix of cross-linked protein having affinity to IgG/Fab fragments in 5mM Sodium phosphate buffer, pH 8.0; (ii) a primary antibody specific to antigen to be detected; (iii) 1ml of IX Sodium Dodecyl Sulfate buffer; (iv) micro-centrifuge tubes; (v) a catalogue comprising instructions and parameters relating to use of the kit; and wherein (vi) the proteins are selected from the group consisting of ProteinA-MNP, ProteinG-MNP, Protein L-MNP, peroxidase-MNP, glutathione-MNP, Bovine serum albumin -MNP, ovalbumin-MNP, amylase-MNP, hemoglobin-MNP, lipase-MNP, Fab-MNP, ScFv-MNP, IgG-MNP, lectin-MNP, calmodulin-MNP, streptavidin-MNP, Albumin-MNP, gelatin-MNP, histone-MNP; and (vii) the biological samples are selected from the group consisting of biological fluids selected from whole blood, serum, plasma and ascites; cell culture and bacterial cell lysate. the kit is a diagnostic kit for immobilization, purification and identification of IgG, Fab fragments or single chain variants, functional proteins from biological samples comprising: (i) 25μgm to 10mg magnetic nanoparticle entrapped in a matrix of cross-linked protein having affinity to IgG/Fab fragments in 5mM Sodium phosphate buffer, pH 8.0; (ii) 25ml washing buffer, i.e. IX phosphate buffer pH 8; (iii) 50ml IgG/Fab fragment elution buffer, i.e. an acidic buffer comprising phosphate buffer pH 2.8; or glycine, pH 2; or L-Arginine, pH 3; (iv) 2ml neutralizing buffer, i.e. 1M Tris, pH 9.0; (v) a catalogue comprising instructions and parameters relating to use of the kit; or (i) 25μgm to 10mg magnetic nanoparticle entrapped in a matrix of cross-linked protein having affinity to IgG/Fab fragments in 5mM Sodium phosphate buffer, pH 8.0; (ii) 25ml washing buffer, i.e. IX phosphate buffer pH 8; (iii) 50ml IgG/Fab fragment elution buffer, i.e. an acidic buffer comprising phosphate buffer pH 2.8; or glycine, pH 2; or L-Arginine, pH 3; (iv) 2ml neutralizing buffer, i.e. 1M Tris, pH 9.0; (v) a catalogue comprising instructions and parameters relating to use of the kit; or the kit is an immunoprecipitation kit for the detection of an immunogen or antigenic proteins comprising (i) 25μg to 10 mg magnetic nanoparticle entrapped in a matrix of cross-linked protein having affinity to IgG/Fab fragments in 5mM Sodium phosphate buffer, pH 8.0; (ii) a primary antibody specific to antigen to be detected; (iii) 1ml of IX Sodium Dodecyl Sulfate buffer; (iv) micro-centrifuge tubes; (v) a catalogue comprising instructions and parameters relating to use of the kit; and wherein (vi) the proteins are selected from the group consisting of ProteinA-MNP, ProteinG-MNP, Protein L-MNP, peroxidase-MNP, glutathione-MNP, Bovine serum albumin -MNP, ovalbumin-MNP, amylase-MNP, hemoglobin-MNP, lipase-MNP, Fab-MNP, ScFv-MNP, IgG-MNP, lectin-MNP, calmodulin-MNP, streptavidin-MNP, Albumin-MNP, gelatin-MNP, histone-MNP; and (vii) the biological samples are selected from the group consisting of biological fluids selected from whole blood, serum, plasma and ascites; cell culture and bacterial cell lysate. (i) 25μg to 10 mg magnetic nanoparticle entrapped in a matrix of cross-linked protein having affinity to IgG/Fab fragments in 5mM Sodium phosphate buffer, pH 8.0; (ii) a primary antibody specific to antigen to be detected; (iii) 1ml of IX Sodium Dodecyl Sulfate buffer; (iv) micro-centrifuge tubes; (v) a catalogue comprising instructions and parameters relating to use of the kit; and wherein (vi) the proteins are selected from the group consisting of ProteinA-MNP, ProteinG-MNP, Protein L-MNP, peroxidase-MNP, glutathione-MNP, Bovine serum albumin -MNP, ovalbumin-MNP, amylase-MNP, hemoglobin-MNP, lipase-MNP, Fab-MNP, ScFv-MNP, IgG-MNP, lectin-MNP, calmodulin-MNP, streptavidin-MNP, Albumin-MNP, gelatin-MNP, histone-MNP; and (vii) the biological samples are selected from the group consisting of biological fluids selected from whole blood, serum, plasma and ascites; cell culture and bacterial cell lysate.