Plasmonic nanoparticles, primarily composed of gold and silver are some of the most promising candidates for bio-molecular sensors and probes. The ability to extract the enhanced properties for these materials relies solely on the ability to control the particle size, shape, structure or composition. While much effort has gone into creating and understanding the resulting properties for gold and silver based nanoparticles, there is still a challenge to overcome in achieving optimized probes which are robust, have high plasmonic activity and possess a strong surface reactivity with a wide range of bio-molecules. The hybridization of particle properties in multi-component nanoparticles offers a powerful route towards achieving this goal. Core@shell nanoparticles composed of silver and gold display a wealth of enhanced sensing properties, yet suffer from two primary drawbacks. The sensitivity of silver to the galvanic replacement reaction and rapid oxidation in the presence of biological levels of salt effectively limits the ability to control the characteristics of these probes either through synthetic technique or in practical use. New studies however have emerged that reveal an enhanced stability for silver when it is coated as a shell onto gold particles. The enhanced resistance of the silver at an interfacial layer in the Au@Ag structure is revealed to arise as a result of a unique electronic transfer phenomenon, which ultimately causes the silver layer to become electron rich, leading to enhanced stability. The finding creates a new avenue for controlling the plasmonic and stability properties for not only gold and silver core@shell nanoparticles for bio-molecular diagnostics, but also for a host of other nanomaterials that can benefit through multicomponent designs.