Provided herein are methods and kits for isothermal nucleic acid amplifications that use a target nucleic acid template; a reaction mixture comprising a DNA polymerase having a strand displacement activity, a deoxyribonucleoside triphosphate (dNTP) mixture, a primer with a 3′ end and a 5′ end, a molecular crowding reagent, and a buffer solution for amplifying the target nucleic acid template. The buffer solution maintains a low salt concentration of the reaction mixture, and wherein the salt concentration results in a melting temperature (Tm) of the primer at least 10° C. below the reaction temperature. The amplification is effected under isothermal condition.