Chemical functionalization of solid-state nanopores and nanopore arrays and applications thereof. Nanopores are extremely sensitive single-molecule sensors. Recently, electron beams have been used to fabricate synthetic nanopores in thin solid-state membranes with sub-nanometer resolution. A new class of chemically modified nanopore sensors are provided with two approaches for monolayer coating of nanopores by: (1) self-assembly from solution, in which nanopores −10 nm diameter can be reproducibly coated, and (2) self-assembly under voltage-driven electrolyte flow, in which 5 nm nanopores may be coated. Applications of chemically modified nanopore are provided including: the detection of biopolymers such as DNA and RNA; immobilizing enzymes or other proteins for detection or for generating chemical gradients; and localized pH sensing.