TECHNOLOGY FOCUS - BIOLOGY - Preferred Matrix: The matrix (A1) comprises microparticles, where the microparticles comprise the bioactive agent. (A1) comprises a bioactive agent; or bioparticles selected from viral particles and cells and further comprises cell attachment factors, and cells are attached to cell attachment factors in the matrix, where the cell attachment factors are covalently attached to the matrix via the linker segments, or are covalently attached to the matrix via a reacted group. The poly- alpha (1-4)glucopyranose polymeric segment is greater than or equal to 50 wt.% of a total weight amount of matrix-forming solids in the matrix.Preferred Method: In (M1), the step of contacting is performed in an aqueous composition including matrix-forming material comprising alpha (1-4)glucopyranose polymer and the second component, and having an amount of matrix forming material of 20-500 mg/ml; or is performed in vivo or in situ. Preferred Components: The bioactive agent comprises a nucleic acid and where the nucleic acid is associated with a carrier component to promote entry of the nucleic acid into a cell. The bioactive agent is selected from polypeptide, polysaccharide, or polynucleotide. The cell attachment factor is selected from fibronectin, vitronectin, laminin A, laminin B1, laminin B2, collagen I, and thrombospondin and its active portions.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The linker segment includes a formula selected from (Q1)-R4-C(O)-NH-NH-C(O)-R5-(Q2) (III) or (Q3)-R4-C(O)-NH-N=CH-R6-(Q4) (IV). The linker segment further comprises an ester group. The hydrazide-reactive groups are selected from aldehyde, acyl halide, NHS-ester, carboxylic acid, imidazole, hydroxymethyl phosphine and unsaturated ester.Q1-Q4=monomeric units alpha (1-4) glucopyranose polymers, or portion of a polymeric component that is different than alpha (1-4) glucopyranose polymer;R4-R6=O or cyclic, linear, or branched carbon-containing groups that contain at least one O or N.Provided that at least one of Q1 or Q2, and at least one of Q3 or Q4 are a monomeric unit of alpha (1-4) glucopyranose polymer.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The second polymeric segment comprises a hydrophilic biocompatible polymer. The hydrophilic biocompatible compound is selected from poly(vinylpyrrolidone) (PVP), poly(ethylene oxide) (PEO), poly(ethyloxazoline), poly(propylene oxide) (PPO), poly(meth)acrylamide (PAA) and poly(meth)acylic acid, polyethylene glycol (PEG), tetraethylene glycol, triethylene glycol, trimethylolpropane ethoxylate, pentaerythritol ethoxylate, PEG-PPO (copolymers of polyethylene glycol and polypropylene oxide), hydrophilic segmented urethane and polyvinyl alcohol. The alpha (1-4)glucopyranose polymer comprises pendent hydrazide groups and has degree of substitution with either first or second reactive groups of 0.1-1. In the alpha (1-4)glucopyranose polymer, the second polymer, or both, have molecular weight less than or equal to 500000 Daltons. A portion of the alpha (1-4)glucopyranose polymer has a formula selected from V-VIII. The second polymer component (P2) comprises alpha (1-4)glucopyranose polymer comprising pendent aldehyde groups.R2, R3=cyclic, linear, or branched carbon-containing group having 1-12C (preferably (CH2)n);n=1-12. EXAMPLE - Into vial, maltodextrin (3 g) was dissolved into anhydrous dimethyl sulfoxide (DMSO) (12 ml). The activating agent, 1,1'-carbonyldiimidazole (CDI) (1.50 g) was dissolved into DMSO (25 ml). The CDI solution was pipetted into the vial containing the maltodextrin and the activation was allowed to proceed for 25 minutes at room temperature while. At the same time, succinic dihydrazide (13.52 g) was solubilized into deionized water (80 ml). The succinic dihydrazide solution was stirred at 55 degrees C for 25 minutes. After work up, maltodextrin-succinyl hydrazide (1.548 mmol) was obtained as a white powder. Into vial, maltodextrin (5 g) was dissolved into 0.05M sodium acetate buffer pH 5.0 (30 ml). The solution was cooled to 5-10 degrees C for 15 minutes. The cooled periodate solution (17.1 ml) was poured into the cooled maltodextrin solution. The reaction remained in an ice bath for two hours. At the end of the time, the reaction solution was quenched with ethylene glycol (3 ml). After work up, maltodextrin-aldehyde was obtained as a white powder. Maltodextrin-succinyl hydrazide was dissolved into deionized water at 250 mg/ml. Maltodextrin aldehyde was also dissolved into water at 250 mg/ml. The two solutions were pipetted together at a 1:1 ratio onto a glass plate where they polymerized immediately upon contact to give maltodextrin matrix as a gel of strong and clear.