Antti Haapala

Cellulose-based materials offer versatile platforms for the development of functional photoactive systems owing to their tunable morphology, high surface area, and biocompatibility. In this study, an allyl-functionalized BODIPY derivative was incorporated into cellulose nanocrystals (CNC), cellulose nanofibers (CNF), and cellulose foam using covalent and non-covalent immobilization strategies. Covalent attachment was achieved through a thiol–ene reaction with thioglycolic acid-modified CNC (CNC–SH), while physical adsorption was employed for CNF and cellulose foam. The reactivity of the allyl-functionalized BODIPY depended strongly on the thiol structure, with enhanced conversion observed for thiols containing adjacent carbonyl groups. Scanning electron microscopy revealed distinct morphologies for the cellulose matrices, ranging from compact CNC aggregates to fibrillar CNF networks and highly porous foam architectures, which influenced dye distribution and accessibility. Biological evaluation using human breast cancer cell lines (MCF-7 and HCC-1806) showed low dark toxicity and pronounced light-induced cytotoxicity that was preserved after immobilization within the cellulose matrices, whereas low toxicity was observed in non-malignant Vero cells. These results demonstrate that cellulose morphology and immobilization strategy govern the biological performance of BODIPY–cellulose hybrid materials and provide design principles for the development of polysaccharide-based photoactive platforms.

Spent mushroom substrate (SMS) is the nutrient-depleted medium left after the commercial cultivation of protein-rich mushrooms such as Agaricus bisporus and Pleurotus ostreatus, which are typically grown on agricultural byproducts. Often discarded as waste, SMS can be converted through hydrothermal liquefaction (HTL) into liquid and solid products with potential applications as soil amendments, crop fertilizers, or alternative pesticides. In this study, liquid products obtained from the hydrothermal liquefaction (HTL) of spent mushroom substrates from A. bisporus and P. ostreatus cultivations were analyzed using direct-infusion ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry. This technique enables nontargeted chemical fingerprinting of complex organic mixtures such as HTL-derived products. The SMS-derived aqueous HTL products were found to be chemically highly diverse, comprising a broad range of heteroatomic (NOS) compounds, including phenolics, sugars, and lipids, along with their nitrogen- and sulfur-containing derivatives. Elemental analysis of the products revealed significant levels of nitrogen and sulfur, along with several inorganic elements commonly associated with nutrients (e.g., Al, Ca, Fe, K, Mg, and P), as well as trace amounts of some other metals. Comprehensive understanding of the chemical composition of HTL products is essential for their further valorization across different applications.

Microplastics morphology, namely size, shape, and texture, play an important role in adhesion of different types of contaminants over a microplastic. In flowing water, this leads to formation of complex contaminant systems which are transported and become a potential hazard for virtually all Earth’s environmental compartments. Here, we provide methods to study morphology and motion of microplastics, and we derive parameters to aid in their early detection and identification in flowing water. On UPVC microplastic we demonstrate ultra-high-definition imaging paired with statistical parameters for light intensity distribution in analogy to surface roughness parameters and perceptual texture parameters derived from a Gray Level Co-occurrence matrix. Further, from LDPE and PS microplastics videos we derived distinct flow behavior parameters of each microplastic type. Finally, we analyse images of a complex water sample, a cellulose-rich influent of a paper mill wastewater treatment plant. The presented findings open a path towards new sensing solutions to detect and identify the type of MP contaminant, predict their location and fate during and after wastewater flow monitoring.

Microplastics morphology, namely size, shape, and texture, play an important role in adhesion of different types of contaminants over a microplastic. In flowing water, this leads to formation of complex contaminant systems which are transported and become a potential hazard for virtually all Earth’s environmental compartments. Here, we provide methods to study morphology and motion of microplastics, and we derive parameters to aid in their early detection and identification in flowing water. On UPVC microplastic we demonstrate ultra-high-definition imaging paired with statistical parameters for light intensity distribution in analogy to surface roughness parameters and perceptual texture parameters derived from a Gray Level Co-occurrence matrix. Further, from LDPE and PS microplastics videos we derived distinct flow behavior parameters of each microplastic type. Finally, we analyse images of a complex water sample, a cellulose-rich influent of a paper mill wastewater treatment plant. The presented findings open a path towards new sensing solutions to detect and identify the type of MP contaminant, predict their location and fate during and after wastewater flow monitoring.

The basic density and shrinkage properties of Scots pine wood from commercial first and second thinning-stage forests were studied in eastern Finland with a reference from final-felling forests. Linear mixed model analysis was applied, indicating statistically significant differences in basic density between stand types and forest site types, with significant effects of cambial age and height position. Additionally, the 2-level interaction terms between site type, cambial age and height position were significant. In Myrtillus type sites, the basic density was 380 kg/m ³ for first-thinning wood, and 407 kg/m ³ and 406 kg/m ³ for second-thinning and final-felling wood, respectively. Young thinning trees showed, on average, wider growth rings (2.83 mm) compared to mature trees (2.04 mm). Density and latewood proportions increased with tree age, particularly in poor site types, whereas the growth ring width had opposite effects. Significant differences were observed in radial, tangential and volumetric shrinkage across stand types, height positions and radial positions, while the longitudinal shrinkage model indicated statistically significant differences between radial positions only. The radial shrinkage was 4.04% in the first thinnings and 4.44% in the second thinnings, while the tangential shrinkage was 6.98% and 7.16%, respectively. The substantial variation in properties, particularly in the first thinnings, likely reflected the presence of juvenile wood, stem form defects and reaction wood in the harvested material, making it less suitable for mechanical processing. The results confirmed that the properties of second-thinning wood enable its use in applications requiring higher density and allowing reasonable shrinkage.

Background and aims: Boron (B) deficiency is widespread in boreal forests, but it can be prevented by fertilization. As B deficiency reduces root growth, it may affect the uptake of other nutrients. We assessed the persistence of the effects of a one-time B application on growth and nutrition of Norway spruce (Picea abies). Methods: A single-tree B-fertilization experiment was established in a highly productive stand in eastern Finland in 2000 and followed until 2018. The applied B dose was 2 kg ha⁻¹. Results: After 19 growing seasons, height growth was higher in B-fertilized trees and the effect was not waning. Diameter growth was not affected. The mean needle-B concentration without B fertilizer was 1.7 mg kg⁻¹ and with B-fertilizer, 4.8 mg kg⁻¹. Boron-fertilized trees had higher foliar aluminium (Al), carbon (C), copper (Cu) and sulfur (S) concentrations, and lower soluble silicon (Si). Conclusions: The positive B effect on growth persisted after 19 years. Boron concentrations remained higher in fertilized trees, although lower than at the early stages of the experiment. Boron fertilization maintained Cu and S levels above deficiency limits. The small but consistent change in C indicates a change in needle compounds. Increased Al may result from reduced Si accumulation, as Al co-deposition with Si alleviates Al toxicity. Further studies are required to optimize B-fertilization practices and to elucidate the mechanisms behind the effects on height growth and the levels of other elements. A combination of soluble and sparingly soluble fertilizers could further increase the duration of the effect.

Wood chips and sawdust are used for cultivating Ganoderma lucidum mushrooms. In Northern Europe, side-streams of Pinus sylvestris are highly abundant, however as cultivation substrate they inhibit the growth of G. lucidum. To identify the changes in lignocellulosic composition after fungal degradation, the major lignocellulosic components in P. sylvestris and an optimal substrate for G. lucidum, Populus tremula were analyzed. Populus tremula was evenly degraded while the glucan fraction of P. sylvestris was not degraded and its lignin fraction was consumed almost completely. Despite not being an optimal substrate, P. sylvestris was successfully delignified by G. lucidum.

The ongoing challenge of viral transmission, exemplified by the Covid pandemic and recurrent viral outbreaks, necessitates the exploration of sustainable antiviral solutions. This study investigates the underexplored antiviral potential of wooden surfaces. We evaluated the antiviral efficacy of various wood types, including coniferous and deciduous trees, against enveloped coronaviruses and nonenveloped enteroviruses like coxsackie virus A9. Our findings revealed excellent antiviral activity manifesting already within 10 to 15 min in Scots pine and Norway spruce, particularly against enveloped viruses. In contrast, other hardwoods displayed varied efficacy, with oak showing effectiveness against the enterovirus. This antiviral activity was consistently observed across a spectrum of humidity levels (20 to 90 RH%), while the antiviral efficacy manifested itself more rapidly at 37 °C vs 21 °C. Key to our findings is the chemical composition of these woods. Resin acids and terpenes were prevalent in pine and spruce, correlating with their antiviral performance, while oak's high phenolic content mirrored its efficacy against enterovirus. The pine surface absorbed a higher fraction of the coronavirus in contrast to oak, whereas enteroviruses were not absorbed on those surfaces. Thermal treatment of wood or mixing wood with plastic, such as in wood-plastic composites, strongly compromised the antiviral functionality of wood materials. This study highlights the role of bioactive chemicals in the antiviral action of wood and opens new avenues for employing wood surfaces as a natural and sustainable barrier against viral transmissions.