## 1 Introduction  
Since the turn of the millennium, a multitude of advanced cellulosic materials has been developed. Their intriguing properties including transparence, low oxygen transmission, high mechanical strength, large specific surface, or tailor-made surface chemical and physical properties [1; 2; 3] literally invite use in both established and novel applications. Diagnostic or theranostic devices in human medicine typically rely on sensitive biosensors and event-triggered controlled release of active compounds. This is also the case for intelligent wound dressings capable of assessing critical protease concentrations in chronic wounds, for example [4; 5]. Beyond the core features allowing for reporting critical levels of a target analyte and triggering a controlled response, respective wound dressings or biosensors interacting with living tissue are required to be biocompatible, free of potentially harmful trace compounds and should have excellent moistening capabilities. Native bacterial cellulose (BC)--an extracellular product of the metabolism of various bacteria--is an ideal material in this respect owing to its inherent purity, hydrophilicity, and mechanical characteristics [6]. These properties are the result of the particular BC nanomorphology, surface chemistry and high cellulose I crystallinity, all virtually unaffected by any harsh chemical or mechanical isolation techniques as common for wood pulp cellulose [6]. While never-dried, sterilized, and uncompressed bacterial cellulose sheets have long been commercially available for medical and cosmetic purposes [7], translucent or even transparent bacterial cellulose sheets (wound dressings) or opaque nanopaper (dipsticks) for bio-sensing applications is an emerging field of material research, such as for luminescence resonance energy transfer based nucleic acid hybridization assays [8]. Optical biosensors in wound dressings are typically composed of biocompatible transducer materials of large accessible internal surface which carry an appropriate fluorescent reporter compound non-fluorescent in bonded state [9]. The latter can be linked to the substrate by a specific peptide which is designed to interact with the respective target analyte, such as human neutroph elastase. As a result, the fluorophore is cleaved off indirectly reporting an elastase concentration dependent optical response [5; 9; 10]. Alternatively, photoluminescence nanoparticles covalently immobilized on the transducer's surface can be used whose optical response is either triggered or quenched depending on the type and concentration of the analyte. Optical nanoscale detection devices nowadays employ a broad variety of zero-, one-, and two- dimensional photoluminescence nanoparticles capable of frequency downconversion (Stokes behavior) or upconversion (_anti_-Stokes photoluminescence; PL). Colloidal core/shell semiconductor quantum dots (QD, zero dimensional) [11], wires (1D), or wells (2D) form one major class of frequency downconversion nanoparticles. They are typically equipped with passivating ligands to prevent photo bleaching and fluorescence intermittency and/or coatings to suppress agglomeration or render QDs water dispersible [12]. Fluorescent carbon-based nanomaterials constitute a more recent type of photoluminescence particles featuring Stokes behavior. This group of materials includes nanodiamonds [13], carbon nanotubes (CNTs) [14], fullerene nanoparticles [15], graphene nanoribbons [16], graphene oxide [17], graphene quantum dots [18], polymer dots [19], and carbon nanodots [20]. Rare earth metal doped nanocrystals [21] are probably the most prominent type of _anti_-Stokes particles. Their PL response is triggered by energy-transfer upconversion (ETU), excited-state absorption (ESA), cooperative sensitization upconversion (CSU) or photon avalanche (PA) [22; 23]. The combination of photoluminescence carbon nanodots with cellulosic carrier materials in fully biobased sensor devices is particularly appealing.