The strive toward sustainability increases the demand for bio-based material production, forcing expansion of the biorefinery feedstock supply from forest wood to non-woody materials such as agricultural residues. As a model organism for legume crops, the aptness of agricultural lupins as a lignocellulose feedstock is investigated. Principle chemical analysis combined with optotracing, in which the fluorescent tracer molecule Carbotrace 680 generates a visual map of the native tissues’ lignocellulose anatomy at sub-cellular resolution, enables informed design of a mild recovery process. A streamlined conversion approach is then designed, yielding lignin-containing microfibrillated cellulose. By monitoring defibrillation and delignification throughout the extraction process, the use of optotracing for non-destructive fiber analytics at unprecedented details across all hierarchical structures of lignocellulosic materials is demonstrated. This crop valorization is a prime illustration of a holistic use of lupin biomass, with seeds serving as plant-based food sources, and other parts as sources for lignocellulose-based materials, thereby expanding both the biorefinery concept and feedstock supply.

The production of lignocellulosic-based materials necessitates leveraging alternative biomasses such as agricultural residues. This study investigates Lupinus angustifolius as a renewable feedstock for lignin-containing microfibrillated cellulose (L-MFC) and explores the role of lignin and hemicellulose in producing lupin-derived L-MFC films. By utilizing mild alkaline pre-treatments (0.5 or 1.5 M NaOH at 90 or 140 °C) and avoiding extensive delignification, four lignocellulose systems with varying lignin and hemicellulose content are generated. To produce L-MFC, these systems were further subjected to a defibrillation process, including TEMPO oxidation and mechanical homogenization. TEMPO oxidation removed partly lignin while preserving hemicellulose, leading to altered biopolymer ratios. Confocal fluorescence microscopy combined with optotracing enabled real-time visualization of the defibrillation process and spatial biopolymer mapping. Complementary excitation-emission matrix (EEM) spectroscopy provided fluorescence fingerprints for tracking molecular-level changes during processing. The resulting lupin-derived L-MFCs were successfully processed into self-standing films using Rapid Köthen drying. Films with higher residual lignin displayed increased hydrophobicity and mechanical strength, especially the R0.5-140-RK system, which achieved a tensile index of ~110 Nm/g and Young’s modulus of ~9700 MPa. This study demonstrates that partial preservation of native lignocellulose architecture offers a viable pathway for sustainable lupin-derived L-MFC film production.

The macroalga Ulva fenestrata plays a key role in marine ecosystems and has increasing potential in aquaculture. However, its three-dimensional tissue architecture remains underexplored. This study applies multimodal fluorescence microscopy combined with optotracing to spatially map biopolymers and structural features in native Ulva tissue. Using Carbotrace 680, cellulose was localized in situ within the cell walls, while oligo/polyaromatic compounds were visualized across multiple scaffold layers via autofluorescence. Lambda scanning validated the fluorescence detection settings for cellulose (Exitation wavelength (Ex.) 561 nm, Emission wavelength (Em.) 570–631 nm), oligo/polyaromatics (Ex. 405 nm, Em. 408–505 nm), and chlorophyll (Ex. 639 nm, Em. 649–693 nm). Spatially resolved biopolymer anatomy maps were generated for blade and rhizoidal tissues, and 3D tissue models were constructed. The outermost blade layer exhibited a sandwich-like architecture, and a previously undescribed median layer was identified separating the two cell layers. This layer was >11 times thicker in rhizoidal tissue than in blade tissue, comprising 56 % and 7 % of the total thickness, respectively. Spectral differences in rhizoidal cells indicated cellular heterogeneity. Collectively, the observed biopolymer and architectural differences may reflect tissue-specific functional specialization of the macroalga. This imaging-based approach provides new perspectives on algal biology and supports the multisectoral valorization of Ulva.

This study presents a decellularization-inspired strategy for isolating the native cell wall scaffold of the tissue of the green macroalgae Ulva fenestrata as platform for bio-based film material. Advancing from conventional bottom-up biopolymer extraction, this top-down approach aims to preserve the inherent hierarchical architecture of the cell wall while reducing chemical use and processing steps. Several extraction protocols were evaluated, revealing that surfactant addition and mechanical pretreatment significantly enhanced decellularization efficiency and scaffold integrity. A high-throughput fluorescence spectroscopy-based method was established for real-time monitoring of pigment extraction kinetics. Cytosolic components were removed, evidenced by the presence of free-floating particles and sheet-like structures, suggesting outer layer detachment. Particle size distribution revealed three distinct fractions, with the smallest likely representing cytosolic remnants.  Biopolymer anatomy mapping revealed that tissue recovery varied with biomass architecture: In the blade tissue, thinner-walled tissues were more susceptible to treatment, whereas thicker-walled tissues retained integrity through an intermediate lamella. Additionally, in both blade and rhizoidal tissues, impairment of the outermost layer significantly enhanced decellularization efficiency. While Carbotrace 680 effectively stained Ulva cell walls in blade tissue, it showed no affinity for the rhizoidal cell walls, which instead were stained by Carbotrace 630, highlighting differences in tissue architecture. Recovered material was fractionated by size for film fabrication into fine, coarse, and mixed films. Tensile testing demonstrated distinct mechanical profiles among the film categories. This sustainable, biomimetic method offers a promising route for developing bio-based films directly from Ulva tissue, preserving native structure while enabling material tunability through process parameters and particle size selection.