AVS 72 Session BI-MoA: The Future of Biointerface Science

Food security and agricultural economies depend on the continued production of grain crops, including barley, wheat and oats. Foliar fungal diseases pose a major threat to grains production worldwide, and solutions to reduce their incidence heavily rely on broadacre fungicide applications after disease occurs. This can be costly, environmentally harmful and eventually promote the emergence of chemically resistant pathogens. Prophylactic strategies to prevent fungal disease occurrence are scarce, but a shared bottleneck to fungal disease progression may a key target for intervention: the fungal pathogen must detect and successfully recognise the host’s surface. This initial point of contact in plant-fungi interactions can hence be reframed as a biointerfaces problem that materials science can address.

The cuticle is a waxy bio-composite that coats the surface of leaves and is comprised of a cutin matrix that is embedded and/or coated with cuticular waxes, long chain aliphatic compounds that display an extensive range of carbon chain lengths and functional groups. Physiologically, the cuticle plays vital roles in water retention and physical defence against disease, however; increasing evidence has demonstrated that some cuticular waxes can signal recognition to pathogenic fungi to promote infection. The complexity of these plant-fungi interactions hence make them challenging to study and require model systems that can assess the effect of individual surface variables on fungal development.

To address this, we propose the development of a biomimetic model system using fabricated wax films to replicate native leaf chemistries on inert substrates. Using fabrication techniques including spin-coating to generate thin films that can be characterised using a suite of analytical techniques to assess their hydrophobicity, thickness, uniformity and morphology, precise tuning of surface physicochemical properties can be achieved. Individual surface parameters can then be disentangled and systematically assessed in the context of fungal development to identify key virulence traits at the leaf surface.

Biomaterials are increasingly being explored as sustainable alternatives to petroleum-derived materials, but many systems that perform well at laboratory scale remain difficult to manufacture reliably at industrial scale. One reason for this disconnect is that biomaterial structure and function are strongly influenced by the physical conditions present during assembly, including flow, transport, dewatering, and drying conditions that differ substantially between laboratory and industrial environments. This talk presents a framework for designing biomaterials with formation conditions and manufacturing environments considered from the outset instead of introducing process constraints only after laboratory optimization. Using papermaking and related large-scale bio-based manufacturing systems as examples, the presentation examines how process-dependent assembly governs interfacial structure development across systems including microfibrillated cellulose, protein-based materials, biofilms, and mycelium composites. Differences between benchtop and industrial processing are discussed in terms of flow behavior, transport limitations, shear history, and consolidation dynamics, demonstrating that scale-dependent physical regimes can produce fundamentally different structures and functional behavior. The talk further outlines a process-integrated framework in which material selection, structure formation, and manufacturing constraints are treated as interconnected design variables. Finally, future needs in process-relevant characterization, multiscale modeling, and experimental tools capable of probing biomaterial formation under realistic manufacturing conditions are discussed. Incorporating formation pathways into biomaterials research may improve reproducibility and help bridge the gap between laboratory discovery and industrial implementation.

Water quality monitoring is essential for environmental protection and public health, yet scalable solutions remain limited. Furthermore, current high-accuracy sensing technologies rely heavily on trained personnel to take discrete aqueous measurements, which are expensive and cannot provide spatial and temporal measurements in high resolution. To address this, we developed a sensor using a diffraction grating and Raspberry Pi imaging to capture spectral data from a large water volume and extract information on analyte concentration through post-processing image analysis techniques. The diffraction-based design and consumer-level parts allow for inexpensive mass production while maintaining sensitivity comparable to commercial spectrophotometers. The system enables simultaneous measurement of turbidity and analyte-specific absorbance with near-continuous, independent operation. The robust and customizable design of the sensor allowed for field deployment in tropical, temperate, and polar climates. These results show that a low-cost diffraction imaging approach can provide customizable, scalable water quality monitoring for widespread deployment over various environmental conditions.

ZnO demonstrates a strong antibacterial action to both Gram-positive and Gram-negative bacteria. At this time, there remains a significant controversy regarding the predominant mechanisms of antibacterial action of ZnO. In our previous work, we proposed a model of the antibacterial action of ZnO, based on the mechanism of surface defect-induced dissolution. For its further validation, we carry out modification of hydrothermally synthesized microparticles of ZnO in order to modulate their antibacterial efficacy in a controlled manner. We hypothesize that the instability of ZnO during antibacterial tests is due to defect-induced reconstruction of polar surfaces, which occurs due to the significant internal dipole moment of the ZnO crystal lattice. Theoretically, doping of ZnO with Fe ions can compensate for this dipole moment and stabilize the free surface without disturbing the crystalline structure. To test this hypothesis, we modify the hydrothermal synthesis protocol in order to obtain microparticles with a controlled Fe doping as well as controlled particle morphologies with varied relative abundance of polar surfaces. Next, we carry out a systematic optoelectronic and physicochemical characterization (scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction spectroscopy, and photoluminescence spectroscopy) of the synthesized particles before and after their interaction with Staphylococcus Aureus bacteria in different nutrient media. This makes it possible to assess the stability of the ZnO surface and establish a relationship between surface changes, the concentration of the doping impurity and the antibacterial activity of the material.

The emergence of antibiotic-resistant pathogens has increased interest in naturally derived antibacterial compounds. 1,8-cineole, a bioactive terpene found in eucalyptus oil, is a promising antibacterial compound; however, high volatility limits sustained application. Plasma-enhanced chemical vapor deposition (PECVD) offers a solvent-free method to convert vaporized 1,8-cineole into conformal plasma-polymerized films. Although PECVD has been previously employed to fabricate 1,8-cineole-derived coatings, plasma-induced fragmentation can alter precursor-derived chemical functionality in the resulting film. Because the biocidal activity of 1,8-cineole is structure-dependent, retention of these precursor-derived motifs may be important for preserving film bioactivity. The relationship between duty cycle and 1,8-cineole derived PECVD film composition has been explored , although no significant difference in chemical composition was elucidated. In addition to duty cycle, substrate position also has been shown to influence the extent of functional group retention in films deposited using other PECVD precursors, thereby influencing film chemistry and morphology. Importantly, the effect of substrate position has not been systematically examined for 1,8-cineole-derived films. Understanding how deposition conditions influence film chemistry and morphology is important because these surface properties can affect wettability, bacterial attachment, biofilm development, and overall biological performance.

In this study, properties of 1,8-cineole-derived films were evaluated as a function of substrate position within an inductively coupled plasma reactor under pulsed and continuous discharge conditions. We hypothesized that pulsed deposition would promote growth from longer-lived, less-fragmented species during plasma-off periods, while continuous deposition would provide a comparison under sustained plasma excitation. Water contact angle measurements confirmed surface modification and showed reproducible positional differences in wettability, with films deposited at the center of the reactor exhibiting the lowest contact angles. Preliminary X-ray photoelectron spectroscopy results suggest that the effect of substrate position depends on discharge mode: pulsed films showed clearer spatial trends in elemental composition and oxygen-containing carbon environments, whereas films deposited under continuous power exhibited weaker positional dependence and greater sample-to-sample variability. These findings indicate that substrate position and discharge mode jointly influence the surface chemistry and wettability of 1,8-cineole-derived films.