Carbon dots, which are less than 10 nm in diameter, have been widely investigated because of their unique luminescence properties and potential for use in bioimaging. In the present work, natural carbon dots (L-CDs) were obtained by molecular aggregation, using ethanol-extracted cellulolytic enzyme lignin. The whole process for the preparation of L-CDs was green and simple to operate and did not use toxic chemical reagents or harsh conditions. The newly prepared L-CDs emitted multicolor photoluminescence following one- and two-photon excitation. The L-CDs also showed good cellular biocompatibility, which is crucial for biological applications. One- and two-photon cell-imaging studies demonstrated the potential of L-CDs for bioimaging.

The purpose of this study was to synthesize hydrophilic cinnamaldehyde Schiff base compounds and investigate those bioactivity. A total of 24 Schiff base compounds were synthesized using a simple approach with 3 cinnamaldehyde derivates and 8 amino acids as raw materials. The structures of synthesized compounds were confirmed using FTIR, 1HNMR, HRMS purity and melting point. The antimicrobial activities of new compounds were evaluated with fluconazole and ciprofloxacin as the control against Aspergillus niger, Penicillium citrinum, Escherichia coli and Staphylococcus aureus. Findings show that major compounds exhibited significant bioactivity. Results from the structure–activity relationship suggest that both –p-Cl on benzene ring of cinnamaldehyde and the number of –COOK of amino acid salts significantly contributed to antimicrobial activity.

To develop new rosin-based wood preservatives with good antifungal activity, 24 rosin derivatives were synthesized, bioassay tested with Trametes versicolor and Gloeophyllum trabeum, and subjected to analysis of their quantitative structure–activity relationships (QSAR). A QSAR analysis using Ampac 9.2.1 and Codessa 2.7.16 software built two QSAR models of antifungal ratio for T. versicolor and G. trabeum with values of R2 = 0.9740 and 0.9692, respectively. Based on the models, tri-N-(3-hydroabietoxy-2-hydroxy) propyl-triethyl ammonium chloride was designed and the bioassay test result proved its better inhibitory effect against the two selected fungi as expected.

Nano-crystalline cellulose was fabricated in an anhydrous phosphoric acid system with medical absorbent cotton as its raw material. After ammonia neutralization, the whole system with produced phosphates and hydrolyzed saccharides was used as a modifier for preparing polyurethane foam (PUF). The NCC worked as a reinforce material, the phosphates served as flame-retardants, and the hydrolyzed saccharides partly replaced polyol. The addition of the modifier significantly improved mechanical property and flame-retardancy without an inferior thermal conductivity. When the dosage of modifier was 6% of the whole polyol, compressive strength increased 4.29 times, heat release rate dropped to 50.7%, and time to ignition extended to 2.6 times of those of the neat PUF. XRD and TEM analyses proved that the NCC in the modifier was rod-shape cellulose Ⅱ with diameter of 10 nm or so. FTIR analysis confirmed that the modifier well reacted with isocyanate, and SEM results revealed that the flame-retardant PUF had more uniform cells and more regular skeleton structure than the neat PUF.