# Recent Development of Morphology Controlled Conducting Polymer Nanomaterial-Based Biosensor
## 1 Introduction  
Biosensors are crucial for numerous applications in healthcare, medical science, agriculture, environmental monitoring, food, and biosecurity because of their extremely precise diagnostic and monitoring capabilities [1; 2; 3; 4; 5]. Analytes are detected with the aid of biological-sensing elements such as antibodies, cells, receptors, and aptamers, which are bound to transducers made from conductive nanomaterials [6; 7; 8]. Quantitative analysis of the target analyte is achieved by selectively converting the molecular recognition processes between the analyte and the biological element bound to the transducers from a nonelectrical domain to an electrical signal [9; 10; 11; 12]. The binding of the analyte induces changes in the electrical properties of the transducers. An effective biosensor exhibits several crucial characteristics, namely, high sensitivity, good selectivity, fast response/recovery time, cycle stability, and the capability to operate at low temperatures. In addition to satisfying all of these prerequisites, conductive nanomaterial-based electrodes are renowned for their small size, high surface-to-volume ratio, and unique optical/electrical properties, thereby making them excellent candidates for biosensor-assisted applications [13; 14; 15; 16; 17]. Conducting polymers are often employed as transducer materials for biosensor applications because of the unique traits inferred by their unusual \(\pi\)-conjugated systems [18; 19; 20; 21; 22]. Conducting polymers contain polyconjugated chains consisting of alternating single (\(\sigma\)) and double (\(\pi\)) bonds that influence the electrical and optical properties of the sensing transducer [23; 24; 25]. Several parameters govern the physical properties of conducting polymers, including the length of the conjugation, the existing intra-/interchain interactions, and the extent of the disorder in the system [26; 27]. Furthermore, research has shown that the partial or total inclusion of conducting polymer nanostructures in sensor transducers leads to significantly improved sensing performance [28; 29; 30; 31; 32]. The ability to selectively tunedefects, electronic states, and the surface chemistry has been the driving force behind diverse methods for fabricating morphologically tunable conducting polymer nanomaterials [33; 34; 35; 36]. Additionally, assembling conducting polymer nanostructures into an ordered array is often necessary to render them functional [37; 38]. Novel nanostructure-based sensing devices exhibit enhanced abilities that are generated through the development of new strategies for combining and assembling nanoscale units [39; 40; 41; 42]. Various synthetic methods have been reported, of which the template method is the most promising and powerful tool for fabricating conducting polymer nanomaterials [43; 44; 45; 46; 47; 48; 49; 50; 51]. The template method involves the inclusion of inorganic or organic guest molecules in the voids of the host material. These voids act as the \"template\", thereby defining the shape, size, and orientation of the compound being produced. Generally, the template method is classified into three different types, namely, hard, soft, and template free methods. Briefly, the \"hard\" template process involves the fabrication of 1D nanostructures such as nanotubes and nanorods using anodic aluminum oxide membranes, track-etched polycarbonates, and zeolites [52; 53; 54; 55]. The \"soft\" template method involves the fabrication of various morphologies of conducting polymer nanomaterials. Here, the templates used include surfactants, liquid-crystalline polymers, cyclodext, and functionalized polymers [56; 57; 58; 59]. Surfactants that include cationic, anionic, and non-ionic amphiphiles are commonly used to form micelles as nanoreactors.