NOVELTY - Modifying (m1) fiber-based substrate surface involves introducing the substrate into reaction chamber; pulsing vapor-phase precursor comprising organic/inorganic component into the chamber to create first by-product species; purging the chamber to remove excess of the precursor and first by-product species; pulsing a vapor-phase reactant into the chamber to complete the formation of atomic layer of desired material and create second by-product species; purging the chamber to remove excess of the reactant and second by-product species; and repeating the pulsing and purging steps.    USE - For modifying a surface of fiber-based substrate (e.g. cotton fiber, cotton fabric, woven cotton fabric, fluorocarbon fiber, fluorocarbon fabric, woven fluorocarbon fabric, non-woven fluorocarbon fabric, glass fiber, glass fabric, woven glass fiber, or non-woven glass fabric) (claimed).    ADVANTAGE - The method controllably and uniformly modify and reproduce arbitrary three-dimensional nano-architectures, including fiber mats and bundles, woven fabrics, and engineered polymer structures, will enable and facilitate new emerging fiber-based and textile products; and fully penetrate fibrous networks. The method utilizes self-limiting reactant adsorption processes that achieve fully conformal functionalization of textile fibers of any continuous shape. This allows for well-controlled surface energy modification. The methods are provided for reproducibly converting the surface of fiber systems into inorganic material forms to, e.g. significantly change the wetting properties of filters and other separation media, or enable template fabrication of hollow nanoscale needles, spheres, or other structures for bio-medical or tissue engineering applications. The modified textile materials meet consumer demand in regards to comfort, ease of care, and health issues, and the modified textile materials protect against mechanical, thermal, chemical, and biological attacks and offer improved durability and performance.    DETAILED DESCRIPTION - Modifying (m1) a surface of fiber-based substrate involves introducing the substrate into a reaction chamber; pulsing a vapor-phase precursor comprising an organic/inorganic component into the chamber to create a partial atomic layer of organic/inorganic component on the substrate and create a first by-product species; purging the chamber to remove excess of the precursor and first by-product species; pulsing a vapor-phase reactant into the chamber to complete the formation of an atomic layer of desired material and create a second by-product species; purging the chamber to remove excess of the reactant and second by-product species; and repeating the pulsing and purging steps until the desired surface modification is achieved. INDEPENDENT CLAIMS are included for the following:    (1) a fiber-based substrate having a modified surface comprising a fiber-based substrate; and thin film formed on the fiber-based substrate, and is formed by the atomic layer deposition of a precursor comprising an organic or inorganic component and a vapor-phase reactant reactive with the organic or inorganic component, where the thin film modifies the fiber-based substrate to have a desired surface;    (2) production (p1) of a high density amine-group functionalized surface on a fiber-based substrate;    (3) production (p2) of a uniformly hydrophilic surface on a fiber-based substrate;    (4) a filter comprising a fabric containing fiber-based substrate prepared by the method (p1) and (p2), and further comprising a bound affinity ligand;    (5) depositing (m2) polymer films on a fiber-based substrate;    (6) a fabric (f1) having a high density amine-group functionalized surface, comprising a fiber-based substrate; and an amine-group functionalized surface formed on the fiber-based substrate, and is formed by the atomic layer deposition of a vapor-phase precursor comprising an inorganic component and a vapor-phase ammonia;    (7) a modified fiber-based substrate comprising a fiber-based substrate; and a polymer film formed on the fiber-based substrate, and is formed by the atomic layer deposition of a vapor-phase reactant comprising an organic monomer and a vapor-phase co-reactant comprising a complementary organic monomer;    (8) depositing a hybrid organic-inorganic film on a fiber-based substrate involving introducing a fiber-based substrate into a reaction chamber; pulsing a vapor-phase reactant comprising a first component comprising an organic/inorganic component into the reaction chamber to create a partial atomic layer on the fiber-based substrate and create a first by-product species; purging the reaction chamber to remove excess of the vapor-phase reactant and the first by-product species; pulsing a vapor-phase co-reactant comprising a second component comprising an organic or an inorganic component depending on the first component into the reaction chamber to complete the formation of an atomic layer of the desired material and create a second by-product species; purging the reaction chamber to remove excess of the vapor-phase co-reactant and the second by-product species; and repeating the pulsing and purging steps until the desired thickness of hybrid films is deposited;    (9) formation of a free-standing micro- or nanostructure involving introducing a fiber core into a reaction chamber; pulsing a vapor-phase precursor comprising an inorganic monomer into the reaction chamber to create a partial atomic layer of the inorganic monomer on the fiber-based substrate and a first by-product species; purging the reaction chamber to remove excess of the vapor-phase precursor and the first by-product species; pulsing a vapor-phase reactant into the reaction chamber to complete the formation of an atomic layer of the desired material and create a second by-product species; purging the reaction chamber to remove excess of the vapor-phase reactant and the second by-product species; repeating the pulsing and purging steps until a desired thickness of a micro- or nanostructure is deposited; and removing the fiber core;    (10) preparation of a micro- or nanostructure involving providing a mold comprising a micro- or nanostructure; introducing the mold into an atomic layer deposition (ALD) reactor system; adjusting ALD process conditions to promote ALD reactant and product diffusion into and out of the mold, where micro- or nanostructure is formed; and removing the mold.