# Fluorescent Composite Cotton Fabric Modified with Crosslinked Chitosan for Theranostic Applications
## 1 Introduction  
Wound healing is a dynamic process that depends on the patient's health status. Traditional wound dressings use a passive approach and aim to create a suitable environment for the healing process [1, 2]. The current understanding of restoration without leaving a scar is for a breathable dressing that creates a clean, moist, and warm environment. These conditions are suitable for rapid revascularization, providing oxygen, nutrients, and growth factors, and for re-epithelialization, preventing the development of chronic wounds. In recent years, modern trends in wound care have focused on a more personalized approach based on the theranostics idea, or the simultaneous diagnosis of the wound condition and treatment as needed [3]. The new advanced materials development performing multiple functions is a promising area for improving patient care. Providing antimicrobial activity to prevent infection and monitoring wound health without removing the dressing creates greater patient treatment comfort [4, 5]. Various methods of coating and surface modification of textile materials are being investigated in order to create and enhance their antibacterial activity. For this purpose, synthetic low and high molecular weight compounds, biopolymers and natural compounds, nanoparticles, and peptidesare used [6; 7; 8; 9]. Textile material modified with a layer of fluorescent stimuli-responsive hydrogel is a forceful tool for theranostic applications in skin care. This composite material has multifunctional properties aiding effective diagnosis, imaging, and successful therapy in different situations, such as skin diseases, injuries, and cosmetic implementation. Among the various approaches, the thin film application on the fabric surface allows localized and precisely controlled release of active therapeutics [10]. Strategies for obtaining ultrathin layers include the Langmuir-Blodgett method, monolayer deposition techniques, and layer-by-layer (LbL) construction [11]. The LbL technique offers enormous freedom in the choice of materials and flexibility in the structural design. It includes multiple components, each with its role within the unified function of releasing a biologically active substance (BAS) [12]. This method does not impose restrictions on the size or shape of the substrate and does not require high temperature or pressure. The deposition on the substrate surface occurs by alternative adsorption of interacting materials through electrostatic forces, hydrogen bonds, covalent bonds, or bio-specific interactions. Different materials can be used for LbL, such as polyelectrolytes, micelles, graphene oxide, nanoparticles, and proteins [13]. Depending on the materials used to produce the multilayer film and the external conditions, the resulting layer can degrade, allowing for the controlled release of BAS. In recent years, natural polyelectrolytes, such as chitosan, alginate, pectin, collagen, etc., have found significant application in this field because they are non-toxic, biodegradable, and biocompatible. Chitosan is a polycationic polymer with a broad spectrum of biological activity against bacteria and fungi and hemostatic properties [14; 15]. Alginate is a polyanionic polymer used for wound dressing as it is a highly absorbent material and very suitable for wounds with high exudate. These natural polymers are stimuli-responsive to pH and temperature, and are applied in drug delivery and textile, especially for textile-based transdermal therapy [16]. Positively charged chitosan can interact with alginate to enhance layer stability and cytocompatibility [17]. Such supramolecular systems have been found to have applications in various fields, as they combine their ability to release drugs in a controlled manner with sensing properties for processes occurring inside and outside the studied system [18]. Recently, we have prepared new composite materials with potential applications as antimicrobial wound dressings releasing BAS.