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Ferritin is a 12 nanometer (nm) diameter iron storage protein complex that is found in most plants and animals. A substantial body of evidence has established that electrons can tunnel through and between ferritin protein nanoparticles and that it exhibits Coulomb blockade behavior, similar to quantum dots and nanoparticles. This evidence can be used to understand the behavior of these particles for use in nanoelectronic devices, for biomedical applications and for investigation of quantum biological phenomena. Ferritin also has magnetic properties that make it useful for applications such as memristors and as a contrast agent for magnetic resonance imaging. This article provides a short overview of this evidence, as well as evidence of ferritin structures in vivo and of tunneling in those structures, with an emphasis on ferritin structures in substantia nigra pars compacta (SNc) neurons. Potential biomedical applications that could utilize these ferritin protein nanoparticles are also discussed.

Bacterial cellulose (BC) has been utilized as a biopolymer matrix for various applications. The advancement of synthetic biology has brought new approaches for its production and functionalization. In this mini-review, we briefly discuss the conventional methods to improve BC production and functionalization, and their challenges. We summarize the application of synthetic biology to address these challenges and its use to develop novel hybrid living materials. Finally, we consider the opportunities and future prospects of synthetic biology in bioengineered materials. National Research Foundation (NRF) This research was partially funded by the Asian Office of Aerospace Research and Development (AOARD) Grant (#FA2386-19-1-4060) and National Research Foundation, Singapore, under its Competitive Research Programme (Award#NRF-CRP22-2019-0005).

In biomolecular electronics, the role of structural order in charge transport (CT) is poorly understood. It has been reported that the metal oxide cores of protein cages (e.g., iron oxide and ferrihydrite nanoparticles (NPs) present in ferritin and E2-LFtn, which is E2 protein engineered with an iron-binding sequence) play an important role in the mechanism of CT. At the same time, the NP core also plays a major role in the structural integrity of the proteins. This paper describes the role of structural order in CT across tunnel junctions by comparing three iron-storing proteins. They are (1) DNA binding protein from starved cells (Dps, diameter (∅) = 9 nm); (2) engineered archaeal ferritin (AfFtn-AA, ∅ = 12 nm); and (3) engineered E2 of pyruvate dehydrogenase enzyme complex (E2-LFtn, ∅ = 25 nm). Both holo-Dps and apo-Dps proteins undergo CT by coherent tunneling because their globular architecture and relative structural stability provide a coherent conduction pathway. In contrast, apo-AfFtn-AA forms a disordered structure across which charges have to tunnel incoherently, but holo-AfFtn-AA retains its globular structure and supports coherent tunneling. The large E2-LFtn always forms disordered structures across which charges incoherently tunnel regardless of the presence of the NP core. These findings highlight the importance of structural order in the mechanism of CT across biomolecular tunnel junctions.

Carbene-based macromolecules are an emerging new stimuli-sensitive class of biomaterials that avoid the impediments of free radical polymerization but maintain a rapid liquid-to-biorubber transition. Activation of diazirine-grafted polycaprolactone polyol (CaproGlu) is limited to UVA wavelengths that have tissue exposure constraints and limited light intensities. For the first time, UVA is circumvented with visible light-emitting diodes at 445 nm (blue) to rapidly activate diazirine-to-carbene covalent cross-linking. Iridium photocatalysts serve to initiate diazirine, despite having little to no absorption at 445 nm. CaproGlu's liquid organic matrix dissolves the photocatalyst with no solvents required, creating a light transparent matrix. Considerable differences in cross-linking chemistry are observed in UVA vs visible/photocatalyst formulations. Empirical analysis and theoretical calculations reveal a more efficient conversion of diazirine directly to carbene with no diazoalkane intermediate detected. Photorheometry results demonstrate a correlation between shear moduli, joules light dose, and the lower limits of photocatalyst concentration required for the liquid-to-biorubber transition. Adhesion strength on ex vivo hydrated tissues exceeds that of cyanoacrylates, with a fixation strength of up to 20 kg·f·cm2. Preliminary toxicity assessment on leachates and materials directly in contact with mammalian fibroblast cells displays no signs of fibroblast cytotoxicity. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Nanyang Technological University Accepted version T.W.J.S. and I.D. are co-inventors of patent application Hygroscopic, Crosslinking Coatings and Bioadhesives; PCT/ SG2018/050452. The project was supported by the Ministry of Education Tier 1 Grant RG17/18 (S): Novel light activated, diazo protecting groups; Ministry of Education Tier 2 Grant (MOE2018-T2-2-114): CaproGlu, double-sided wet tissue adhesives; NTUitive POC (Gap) Fund NGF/2018/05: Aesthetic Applications of CaproGlu Bioadhesives; and A*Star IAF PP Grant (H19/01/a0/0II9): CathoGlu Bioadhesives-preventing catheter extravasation and skin infections. L.B. acknowledges funding from the Spanish Ministry of Science and Innovation (MCIU), project PID2019- 104654GB-I00.

Coacervates are dense microdroplets formed by liquid-liquid phase separation (LLPS) of macromolecules that have gained increasing attention as drug delivery vehicles. Recently, we have reported a new intracellular delivery system based on self-coacervating histidine (His)-rich beak peptides (HBpep and HBpep-SP) inspired by beak proteins of the Humboldt squid. These peptide microdroplets combine excellent encapsulation efficiency of therapeutics with high transfection rate and low cytotoxicity. However, the mechanism by which they cross the cell membrane remains elusive. Previous inhibitor studies provided incomplete clues into the detail uptake pathway, although they suggested a cholesterol-dependent and, possibly, an energy-independent non-classical mechanism of internalization. In this study, we improved our understanding of coacervates/cell membrane interactions using model membranes, namely Giant Unilamellar Vesicles (GUVs) and Giant Plasma Membrane Vesicles (GPMVs). We also employ a combination of electron microscopy techniques to gain detailed structural insights into the cell uptake of HBpep and HBpep-SP coacervates. We demonstrate that modulating lipid charge and cholesterol level influence coacervate attachment to GUVs. However, they are not able to cross the GUV’s lumen in an energy-independent manner. We then show that the coacervates enter HeLa and HepG2 cells via a mechanism sharing morphological features of macropinocytosis and phagocytosis, in particular involving cytoskeleton rearrangement and capture by filipodia. Our study provides key insights into the interaction of HPpep and HBpep-SP coacervates with model membranes as well as their cellular uptake pathway.

The wet environment in the oral cavity is challenging for topical disease management approaches. The compromised material properties leading to weak adhesion and short retention (8 h) in such environment result in frequent reapplication of the therapeutics. Composites of bacterial cellulose (BC) and carbene-based bioadhesives attempt to address these shortcomings. Previous designs comprised of aqueous formulations. The current design, for the first time, presents dry, shelf-stable cellulose patches for convenient ready-to-use application. The dry patches simultaneously remove tissue surface hydration while retaining carbene-based photocuring and offers on-demand adhesion. The dry patch prototypes are optimized by controlling BC/adhesive mole ratios and dehydration technique. The adhesion strength is higher than commercial denture adhesives on soft mucosal tissues. The structural integrity is maintained for a minimum of 7 days in aqueous environment. The patches act as selective nanoporous barrier against bacteria while allowing permeation of proteins. The results support the application of BC-based adhesive patches as a flexible platform for wound dressings, drug depots, or combination thereof.

Bacterial cellulose (BC) based hybrid hydrogels and aerogels have been fabricated by reformatting BC pellicles. BC pellicles are formed by tight fibrillar networks making it challenging to incorporate other materials to form hybrids or composites. In this study, BC pellicles produced from two Acetobacteracea family members are disintegrated into individual nanofibrils via TEMPO-mediated oxidation. The individualized BC nanofibrils about tens of microns in length and 20–50 nm in width are well-dispersed in water with crystallinity and birefringence of cellulose I. These BC nanofibril dispersions are non-Newtonian fluid. Upon complexation with 0.75 mmol/g of Fe3+, the formed BC nanofibril hydrogels display 17-fold increase in storage moduli. Composite aerogels formed by complexation with conductive polymer PEDOT/PSS show characteristics of a non-Hookean foam material with conductivity value of up to 0.86 S/cm for cellulose density of 4.2 mg/cm2.

Enzymes, receptors, and carrier proteins discriminate between enantiomers of natural and synthetic chemicals. Whereas the structural details of this phenomenon have been investigated in enzymes and receptors, much less is known for carrier proteins of hydrophobic ligands, particularly concerning the contribution of asymmetric centers in the side chains of amino acids to chirally selective binding. Working with a pig odorant-binding protein, we have found that the replacement of either one or both isoleucine residues in the binding pocket by leucines abolishes discrimination of menthol and carvone enantiomers. The results indicate that isoleucines are crucial for chiral discrimination of hydrophobic ligands, and that asymmetry in the side chain may be as important as the overall asymmetry of the protein. The results provide suggestions and guidelines for improving chiral selectivity of binding proteins and enzymes, with consequent applications in the production of enantiomerically pure drugs.

The development of protein-polymer complexes using protein cages is garnering attention as a strategy to overcome challenges that relate to immunogenicity and protease degradation. We propose the use of thermoresponsive polymers such as poly(N-isopropylacrylamide) (PNIPAM) to form ferritin-polymer complexes through non-covalent interactions. Ferritin is observed to be released from the complexes after 1–2 days incubation at 37 °C.

Bacterial cellulose (BC), a renewable type of cellulose, has been used in the manufacture of foods, cosmetics, and biomedical products. To produce BC, a high-throughput single-bacterium measurement is necessary to identify the functional bacteria that can produce BC with sufficient amount and desirable morphology. In this study, a continuous-flow intelligent optofluidic device was developed to enable high-throughput single-bacterium profiling of BC. Single bacteria were incubated in agarose hydrogel particles to produce BC with varied densities and structures. An intelligent convolutional neural network (CNN) computational method was developed to analyze the scattering patterns of BC. The BC production and morphology were determined with a throughput of ∼35 bacteria per second. A total of ∼105 single-bacterium BC samples were characterized within 3 hours. The high flexibility of this approach facilitates high-throughput comprehensive single-cell production analysis for a range of applications in engineering biology.

Protein cages (viral and non-viral) found in nature have evolved for a variety of purposes and are found in all kingdoms of life. The main functions of these nanoscale compartments are the protection and delivery of nucleic acids e.g. virus capsids, or the enrichment and sequestration of metabolons e.g. bacterial microcompartments. This review focuses on recent developments of protein cages for use in immunotherapy and therapeutic delivery. In doing so, we highlight the unique ways in which protein cages have informed on fundamental principles governing bio-nano interactions. With the enormous existing design space among naturally occurring protein cages, there is still much to learn from studying them as biomimetic particles.

(1) Background: This paper aims to present and discuss the most significant challenges encountered by STEM professionals associated with remote working during the COVID-19 lockdowns. (2) Methods: We performed a qualitative analysis of 921 responses from professionals from 76 countries to the open-ended question: "What has been most challenging during the lockdown for you, and/or your family?" (3) Findings: Participants reported challenges within the immediate family to include responsibilities for school, childcare, and children's wellbeing; and the loss of social interactions with family and friends. Participants reported increased domestic duties, blurred lines between home and work, and long workdays. Finding adequate workspace was a problem, and adaptations were necessary, especially when adults shared the same setting for working and childcare. Connectivity issues and concentration difficulties emerged. While some participants reported employers' expectations did not change, others revealed concerns about efficiency. Mental health issues were expressed as anxiety and depression symptoms, exhaustion and burnout, and no outlets for stress. Fear of becoming infected with COVID-19 and uncertainties about the future also emerged. Pressure points related to gender, relationship status, and ethnicities were also evaluated. Public policies differed substantially across countries, raising concerns about the adherence to unnecessary restrictions, and similarly, restrictions being not tight enough. Beyond challenges, some benefits emerged, such as increased productivity and less time spent getting ready for work and commuting. Confinement resulted in more quality time and stronger relationships with family. (4) Interpretation: Viewpoints on positive and negative aspects of remote working differed by gender. Females were more affected professionally, socially, and personally than males. Mental stress and the feeling of inadequate work efficiency in women were caused by employers' expectations and lack of flexibility. Working from home turned out to be challenging, primarily due to a lack of preparedness, limited access to a dedicated home-office, and lack of previous experience in multi-layer/multi-scale environments. Published version Funding has been received from the International Union for Physical and Engineering Sciences in Medicine (IUPESM) towards data analysis.

Topical treatments for oral wounds and infections exhibit weak adhesion to wet surfaces which results in short retention duration (6-8 hours), frequent dosing requirement and patient incompatibility. To address these limitations, aqueous composites made of fibrillated bacterial cellulose and photoactive bioadhesives are designed for soft epithelial surfaces. The aqueous composites crosslink upon photocuring within a minute and exhibit a transition from viscous to elastic adhesive hydrogels. The light-cured composites have shear moduli mimicking oral mucosa and other soft tissues. The tunable adhesion strength ranges from 3 to 35 kPa on hydrated tissue-mimicking surfaces (collagen film). The results support the application of bacterial cellulose hydrogel systems for potential treatment of mucosal wounds. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Submitted/Accepted version The project is partially supported by A*STAR IAF PP Grant (H19/01/a0/0II9): CathoGlu Bioadhesives-preventing catheter extravasation and skin infections; Ministry of Education Tier 2 Grant: CaproGlu, Double sided wet-tissue adhesives (MOE2018-T2-2-114).

Resistance to doxorubicin (DOX) remains a big challenge to breast cancer treatment especially for triple negative breast cancer (TNBC). Our previous study revealed that the antioxidant system plays an important role in conferring metastasis derived DOX resistance. In this study, we used two-dimensional difference gel electrophoresis (2D-DIGE) proteomics to compare the expression profiles of two generations of TNBC cell lines which have increased metastatic ability in nude mice and exhibited resistance to DOX. Through careful analyses, one antioxidant protein: glucose-6-phosphate dehydrogenase (G6PD) was identified with 3.2-fold higher level in metastatic/DOX-resistant 231-M1 than its parental 231-C3 cells. Analyses of clinical data showed that TNBC patients with higher G6PD levels exhibited lower overall survival than patients with lower G6PD level. Reducing G6PD expression by siRNA or inhibiting its activity with dehydroepiandrosterone (DHEA) significantly increased DOX's cytotoxicity in both cell lines. Importantly, inhibiting G6PD's activity with DHEA dramatically increased the apoptotic rate of 1.25 µM DOX from 2% to 54%. Our results suggest that high level of G6PD can help TNBC to resist DOX-induced oxidative stress. Thus, inhibiting G6PD shall be a good strategy to treat DOX-resistant TNBC. Ministry of Education (MOE) Published version This work was supported by the Tier 2 grant (MOE2014-T2-1-025) from the Ministry of Education (MOE) of Singapore and The Science and Technology Development Fund of Macao SAR, China (File No. 083/2016/A2).

Bacterial cellulose (BC) has found applications in various fields ranging from healthcare to electronics. Functionalization of cellulose to impart conductive properties has been met with challenges due to superficial coating rather than uniform interactions with the conducting polymers. In this work, mechanical disruption is shown to be a facile strategy to develop BC-PEDOT:PSS conductive foams without the use of any harsh chemical treatments to functionalize cellulose. The strategy allows for uniform polymer intercalation with the cellulose nanofibers imparting superior conductive properties to the functional material. The conductive foams with low PEDOT:PSS ratio exhibit conductivity of 0.7 S/cm and are cytocompatible with human dermal fibroblasts (HDFa) cells. National Research Foundation (NRF) This research was funded by National Research Foundation (NRF) Biological Design, Tools, and Applications (BDTA) Grant (#NRF2013-THE001-046).

Understanding the mechanisms of charge transport (CT) across biomolecules in solid-state devices is imperative to realize biomolecular electronic devices in a predictive manner. Although it is well-accepted that biomolecule-electrode interactions play an essential role, it is often overlooked. This paper reveals the prominent role of graphene interfaces with Fe-storing proteins in the net CT across their tunnel junctions. Here, ferritin (AfFtn-AA) is adsorbed on the graphene by noncovalent amine-graphene interactions confirmed with Raman spectroscopy. In contrast to junctions with metal electrodes, graphene has a vanishing density of states toward its intrinsic Fermi level ("Dirac point"), which increases away from the Fermi level. Therefore, the amount of charge carriers is highly sensitive to temperature and electrostatic charging (induced doping), as deduced from a detailed analysis of CT as a function of temperature and iron loading. Remarkably, the temperature dependence can be fully explained within the coherent tunneling regime due to excitation of hot carriers. Graphene is not only demonstrated as an alternative platform to study CT across biomolecular tunnel junctions, but it also opens rich possibilities in employing interface electrostatics in tuning CT behavior. Ministry of Education (MOE) Published version We acknowledge the Ministry of Education (MOE) for supporting this research under award no. MOE2019-T2-1-137.

Refereed/Peer-reviewed Women in Medical Physics and Biomedical Engineering (WiMPBME) is a Task Group established in 2014 under the International Union of Physical and Engineering Scientists in Medicine (IUPESM). The group’s main role is to identify, develop, implement, and coordinate various tasks and projects related to women’s needs and roles in medical physics and biomedical engineering around the world. The current paper summarizes the past, present and future goals and activities undertaken or planned by the Task group in order to motivate, nurture and support women in medical physics and biomedical engineering throughout their professional careers. In addition, the article includes the historical pathway followed by various women’s groups and subcommittees from 2004 up to the present day and depicts future aims to further these professions in a gender-balanced manner.

With a significant proportion of the global population growing older (>60 years), the low success rates of current diagnoses for early neurodegeneration signs are disappointing. Early detection of Alzheimer's disease (AD) can improve acclimatization and quality of life for patients in their later years. Endogenous proteins, such as the most abundant secreted protein in cerebrospinal fluid, lipocalin‐type prostaglandin d synthase (L‐PGDS), can bind the early toxic oligomers of amyloid β (Aβ) peptides implicated in AD and prevent their aggregation. Herein, the utility of L‐PGDS for detection of amyloids is demonstrated. L‐PGDS is conjugated with different iron‐oxide magnetic nanoparticles for contrast‐enhanced visualization using magnetic resonance imaging (MRI). These conjugates inhibit amyloid aggregation in vitro and improve viability in neuronal cells incubated with amyloid fibrils, showing a potential neuroprotective function. L‐PGDS‐ferritin conjugates, when administered intraventricularly, localize to AD‐associated amyloid‐rich regions in mice brain imaged using MRI and histological stains. As a proof‐of‐concept, it is demonstrated that L‐PGDS conjugates could reach the brain regions through non‐invasive intranasal administration. These conjugates are developed as the first entirely protein‐based nanoprobes for early detection of brain amyloids. The results of this study open a wider avenue for study of endogenous proteins as potential theranostics for AD.

Hyperpigmentation is a major cosmetic concern that results from the overproduction of melanin from melanocyte cells in the skin. Current formulations of therapeutic drugs and active molecules that are intended to be delivered to the melanocytes are not targeted, leading to inefficient delivery and undesirable side effects. There is a compelling need for delivery vehicles that target melanocytes to effectively regulate melanin production. Self‐assembling protein nanocages (PNCs) have been shown to offer safe and efficient delivery of active molecules. They are versatile protein nanoparticle platforms that can be engineered to display functional ligands to impart specific biological functions. In this work, E2 PNCs are engineered to display alpha‐melanocyte‐stimulating hormone (AlphaMSH) peptides as ligands for targeting and enhancing uptake by melanocytes. At 500 pM, the AlphaMSH‐modified E2 PNCs show 4‐fold increase in melanocyte cell uptake compared to bare E2 PNCs in 2 hours. This increase was less pronounced in keratinocytes. Competitive inhibition assay proves that the MC1R melanocyte cell surface receptor facilitates the uptake of E2 PNCs by mediating interaction with the displayed AlphaMSH peptides. PNCs can thus be used as targeted delivery vehicles of drugs and active molecules to melanocytes for the management of hyperpigmentation.

Accumulation of lipid-laden macrophages (foam cells) is characteristic of atherosclerosis development in the arterial walls. Ferritin nanocages have been found to passively accumulate in the atherosclerotic plaque. Ferritin has been actively investigated as a carrier for contrast agents in atherosclerosis diagnosis. We demonstrate the potential of ferritin as a carrier for therapeutic molecules to mediate cholesterol reduction from foam cells. Cyclodextrin molecules are chemically conjugated to the ferritin nanocages surface or encapsulated within the nanocages using metal co-loading methods. The cyclodextrin-conjugated ferritin has nanomolar affinity to cholesterol molecules. Treatment of foam cells with the conjugates shows decreased levels of intracellular accumulated cholesterol. The preferential localization of ferritin to foam cells is due to transferrin receptor-mediated endocytosis process. These findings show that ferritin nanocages as carriers localize cyclodextrin molecules to foam cells which mediate intracellular cholesterol reduction, thus highlighting its potential use as a therapeutic agent.

Misfolding of Amyloid β (Aβ) peptides leads to the formation of extracellular amyloid plaques. Molecular chaperones can facilitate the refolding or degradation of such misfolded proteins. Here, for the first time, we report the unique ability of Lipocalin-type Prostaglandin D synthase (L-PGDS) protein to act as a disaggregase on the pre-formed fibrils of Aβ(1–40), abbreviated as Aβ40, and Aβ(25–35) peptides, in addition to inhibiting the aggregation of Aβ monomers. Furthermore, our proteomics results indicate that L-PGDS can facilitate extraction of several other proteins from the insoluble aggregates extracted from the brain of an Alzheimer’s disease patient. In this study, we have established the mode of binding of L-PGDS with monomeric and fibrillar Aβ using Nuclear Magnetic Resonance (NMR) Spectroscopy, Small Angle X-ray Scattering (SAXS), and Transmission Electron Microscopy (TEM). Our results confirm a direct interaction between L-PGDS and monomeric Aβ40 and Aβ(25–35), thereby inhibiting their spontaneous aggregation. The monomeric unstructured Aβ40 binds to L-PGDS via its C-terminus, while the N-terminus remains free which is observed as a new domain in the L-PGDS-Aβ40 complex model.

The unique properties of graphene quantum dots (GQDs) which include high loading capacity, excellent physiological stability, strong photoluminescence, biocompatibility, and facile production make them attractive nanomaterials for biomedical applications. In this work, GQDs have been explored as dual-functional targeted drug carriers and cellular bioimaging agents. The GQDs were conjugated to single chain variable fragment of antibody (scFv), which had been engineered with high affinity (B10) to epidermal growth factor receptor (EGFR), via amide covalent linkages (GQDs-scFvB10). The morphology and surface modification of GQDs were characterized by HRTEM, SDS-PAGE, FT-IR, UV-vis and fluorescence spectroscopies. Western blot analysis along with the confocal imaging of EGFR-overexpressing breast cancer cells (MDA-MB-231) demonstrated the targeting functionality of scFvB10 after conjugation to the GQDs, as well as the potential application of GQDs-scFvB10 in targeted bioimaging. The surface of targeted GQDs had a high cisplatin (CDDP) loading capacity of 50% and a pH-dependent release with slower release rate at neutral conditions, which can reduce the commonly observed systemic toxicity of CDDP. The targeted CDDP-loaded nanocarriers ((CDDP)GQDs-scFvB10) exhibited significantly higher toxicity on MDA-MB-231 cells compared to non-targeted ones suggesting their efficient uptake through EGFR. In contrast, cells with saturated EGFR showed lower uptake and cytotoxic effect of (CDDP)GQDs-scFvB10, demonstrating selectivity of the nanocarriers towards EGFR-overexpressing cells. The scFvB10-functionalized GQD is a promising platform for targeted cellular imaging and delivery of CDDP through interactions with EGFRs. This work was funded partially by NTU-Northwestern Institute for Nanomedicine at Nanyang Technological University, Singapore. The authors thank Arun Kumar Prabhakar for his assistance with the initial GQDs preparation, Barindra Sana and Valerie Loh for the reconstruction of the plasmid containing scFvB10 gene.

Circulation of cancer cells in the bloodstream is a vital step for distant metastasis, during which cancer cells are exposed to hemodynamic shear stress (SS). The actions of SS on tumor cells are complicated and not fully understood. We previously reported that fluidic SS was able to promote migration of breast cancer cells by elevating the cellular ROS level. In this study, we further investigated the mechanisms regulating SS-promoted cell migration and identified the role of MnSOD in the related pathway. We found that SS could enhance tumor cell adhesion to extracellular matrix and endothelial monolayer, and MnSOD also regulated this process. Briefly, SS stimulates the generation of mitochondrial superoxide in tumor cells. MnSOD then converts superoxide into hydrogen peroxide, which activates ERK1/2 to promote tumor cell migration and activates FAK to promote tumor cell adhesion. Combining our previous and present studies, we present experimental evidence on the pro-metastatic effects of hemodynamic SS and reveal the underlying mechanism. Our findings provide new insights into the nature of cancer metastasis and the understanding of tumor cell responses to external stresses and have valuable implications for cancer therapy development. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

Topical approaches to oral diseases require frequent dosing due to limited wound retention times. A mucoadhesive drug delivery platform is proposed for oral wound sites with soft tissue adhesion capability of up to 7 days. Bacterial cellulose (BC) and photoactivated carbene-based bioadhesives are combined to yield flexible film platform for interfacing soft tissues in dynamic, wet environments. Structure-activity relationships evaluate UV dose and hydration state with respect to adhesive strength on soft tissue mimics. The bioadhesive composite has an adhesion strength ranging from 7-17 kPa and duration exceeding 48 hours in wet conditions under sustained shear forces, while other mucoadhesives based on hydrophilic macromolecules exhibit adhesion strength of 0.5-5 kPa and last only a few hours. The work highlights the first evaluation of BC composites for mucoadhesive treatments in the buccal cavity. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Accepted version The project is partially supported by RG17/18 (S); Wound Care Innovation for the Tropics Grant. A*STAR IAF PP Grant (H19/01/a0/ 0II9): CathoGlu Bioadhesives-preventing catheter extravasation and skin infections; Ministry of Education Tier 2 Grant: CaproGlu, Double sided wet-tissue adhesives (MOE2018-T2-2-114); Ministry of Education Tier 1 Grant: Novel light activated, diazo protecting groups.

Imaging of immune cells has wide implications in understanding disease progression and staging. While optical imaging is limited in penetration depth due to light properties, magnetic resonance (MR) imaging provides a more powerful tool for the imaging of deep tissues where immune cells reside. Due to poor MR signal to noise ratio, tracking of such cells typically requires contrast agents. This report presents an in-depth physical characterization and application of archaeal magnetoferritin for MR imaging of macrophages - an important component of the innate immune system that is the first line of defense and first responder in acute inflammation. Magnetoferritin is synthesized by loading iron in apoferritin in anaerobic condition at 65 °C. The loading method results in one order of magnitude enhancement of r

Tunnel junctions based on Fe storing globular proteins are an interesting class of biomolecular tunnel junctions due to their tunable Fe ion loading, symmetrical structure and thermal stability, and are therefore attractive to study the mechanisms of charge transport (CT) at the molecular level. This paper describes a temperature-induced change in the CT mechanism across junctions with large globular (similar to 25 nm in diameter) E2-proteins bioengineered with Fe-binding peptides from ferritin (E2-LFtn) to mineralise Fe ions in the form of iron oxide nanoparticles (NPs) inside the protein's cavity. The iron oxide NPs provide accessible energy states that support high CT rates and shallow activation barriers. Interestingly, the CT mechanism changes abruptly, but reversibly, from incoherent tunnelling (which is thermally activated) to coherent tunnelling (which is activationless) across the E2-LFtn-based tunnel junctions with the highest Fe ion loading at a temperature of 220-240 K. During this transition the current density across the junctions increases by a factor of 13 at an applied voltage of V = -0.8 V. X-ray absorption spectroscopy indicates that the iron oxide NPs inside the E2-LFtn cages undergo a reversible phase transition; this phase transition opens up new a tunnelling pathway changing the mechanism of CT from thermally activated to activationless tunnelling despite the large size of the E2-LFtn and associated distance for tunnelling. Ministry of Education (MOE) Published version D. Q. acknowledges the support of the Australian Research Council (Grant No. FT160100207). We acknowledge the Ministry of Education (MOE) for supporting this research under award no. MOE2019-T2-1-137. Prime Minister’s Office, Singapore, under its Medium-sized centre program is also acknowledged for supporting this research.

We report exceptionally large tunnel magnetoresistance (TMR) for biomolecular tunnel junctions based on ferritins immobilized between Ni and EGaIn electrodes. Ferritin stores iron in the form of ferrihydrite nanoparticles (NPs) and fulfills the following roles: (a) it dictates the tunnel barrier, (b) it magnetically decouples the NPs from the ferromagnetic (FM) electrode, (c) it stabilizes the NPs, and (d) it acts as a spin filter reducing the complexity of the tunnel junctions since only one FM electrode is required. The mechanism of charge transport is long-range tunneling which results in TMR of 60 ± 10% at 200 K and 25 ± 5% at room temperature. We propose a magnon-assisted transmission to explain the substantially larger TMR switching fields (up to 1 Tesla) than the characteristic coercive fields (a few Gauss) of ferritin ferrihydrite particles at T < 20 K. These results highlight the genuine potential of biomolecular tunnel junctions in designing functional nanoscale spintronic devices., We acknowledge the Ministry of Education (MOE) for supporting this research under award No. MOE2019-T2-1-137. Prime Minister's Office, Singapore under its Medium sized center program is also acknowledged for supporting this research. We kindly acknowledge the Singapore Synchrotron Light Source (SSLS) supporting our experiments at the SINS beam line under NUS core support C-380-003-003-001. We would like to acknowledge beamline scientists Dr Bruce Cowie and Dr Anton Tadich (soft x-ray (SXR) Beamline at the Australian Synchrotron) for their immense support. E d B acknowledges support from the US National Science Foundation (Grant No.: ECCS#1916874). S R acknowledges funding from CA2DM-NUS during his stay in Singapore. ICN2 is funded by the CERCA programme/generalitat de Catalunya, and the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2017-0706).

The quest to develop ideal nanoparticles capable of molecular, cellular, and tissue level imaging is ongoing. Since certain imaging probes and nanoparticles face drawbacks such as low aqueous solubility, increased ROS generation leading to DNA damage, apoptosis, and high cellular/organ toxicities, the development of versatile and biocompatible nanocarriers becomes necessary. Protein nanoparticles (PNPs) are one such promising class of nanocarriers that possess most of the desirable properties of an ideal nanocarrier for bioimaging applications. PNPs demonstrate high aqueous solubility, minimal cytotoxicity, and multi-cargo loading capacity. They are also amenable to surface-functionalization, as well as modulation of their hydrophobicity and hydrophilicity. The use of PNPs for bioimaging applications has made rapid advancements in the past two decades. Being comparatively less explored, the field opens up a plethora of opportunities and focus areas to engineer ideal bioimaging protein nanocarriers. The use of PNPs as carriers of their natural ligands as well as other heavy metals and fluorescent probes, along with drug molecules for combined theranostic applications has been reported. In addition, surface functionalization to impart specificity of targeting the PNPs has been shown to reduce nonspecific cellular interactions, thus reducing systemic toxicity. PNPs have been explored for their application in imaging of numerous cancers, cardiovascular diseases as well as imaging of the brain using near infrared fluorescence (NIRF) imaging, magnetic resonance imaging (MRI), X-ray computed tomography (CT), positron emission tomography (PET), single-photon emission computed tomography (SPECT), ultrasound (US), and photoacoustic (PA) imaging. Nanyang Technological University This work is partially supported by the School of Chemical and Biomedical Engineering at Nanyang TechnologicalUniversity, Singapore.

The utilization of surface-active engineered protein nanocages as stabilizers for emulsions provides avenues for the design of new tailor-made functional materials in various fields including food, pharmaceutical, and biotechnology. They can be used to codeliver bioactive molecules of different polarities in a tailored manner to the body, act as a platform for screening cells or enzymes, or function as targeted drug delivery systems. Knowledge on the mechanisms that underlie the protein nanocage-driven stabilization of emulsions and their colloidal structure can have direct implications for the rational design of the new advanced functional colloids. This contribution summarizes the recent progress in protein nanocage-stabilized emulsions. It discusses the advances in the precision bioengineering of protein nanocages for emulsion design, highlights challenges in the characterization of structure and dynamics in these materials, and demonstrates selected applications in the field of functional food materials. Published version The work was supported by NTUitive (project no. NGF-2018-04-022) to S.L. and the Swiss National Science Foundation (project no. 200021_192051) to S.S.

The COVID-19 pandemic has forced many people, including those in the fields of science and engineering, to work from home. The new working environment caused by the pandemic is assumed to have a different impact on the amount of work that women and men can do from home. Particularly, if the major burden of child and other types of care is still predominantly on the shoulders of women. As such, a survey was conducted to assess the main issues that biomedical engineers, medical physicists (academics and professionals), and other similar professionals have been facing when working from home during the pandemic. A survey was created and disseminated worldwide. It originated from a committee of International Union for Physical and Engineering Sciences in Medicine (IUPESM; Women in Medical Physics and Biomedical Engineering Task Group) and supported by the Union. The ethics clearance was received from Carleton University. The survey was deployed on the Survey Monkey platform and the results were analyzed using IBM SPSS software. The analyses mainly consisted of frequency of the demographic parameters and the cross-tabulation of gender with all relevant variables describing the impact of work at home. A total of 921 responses from biomedical professions in 76 countries were received: 339 males, 573 females, and nine prefer-not-to-say/other. Regarding marital/partnership status, 85% of males were married or in partnership, and 15% were single, whereas 72% of females were married or in partnership, and 26% were single. More women were working from home during the pandemic (68%) versus 50% of men. More men had access to an office at home (68%) versus 64% for women. The proportion of men spending more than 3 h on child care and schooling per day was 12%, while for women it was 22%; for household duties, 8% of men spent more than 3 h; for women, this was 12.5%. It is interesting to note that 44% of men spent between 1 and 3 h per day on household duties, while for women, it was 55%. The high number of survey responses can be considered excellent. It is interesting to note that men participate in childcare and household duties in a relatively high percentage; although this corresponds to less hours daily than for women. It is far more than can be found 2 and 3 decades ago. This may reflect the situation in the developed countries only—as majority of responses (75%) was received from these countries. It is evident that the burden of childcare and household duties will have a negative impact on the careers of women if the burden is not more similar for both sexes. It is important to recognize that a change in policies of organizations that hire them may be required to provide accommodation and compensation to minimize the negative impact on the professional status and career of men and women who work in STEM fields. Refereed/Peer-reviewed

Electrical field-induced charge modulation in graphene-based devices at the nanoscale with ultrahigh density carrier accumulation is important for various practical applications. In bilayer graphene (BLG), inversion symmetry can simply be broken by an external electric field. However, control over charge carrier density at the nanometer scale is a challenging task. Here, we demonstrate local gating of bilayer graphene (BLG) in the nanometer range by adsorption of AfFtn-AA (which is a bio-engineered ferritin, an iron storing globular protein with ∅ = 12 nm). Low-temperature electrical transport measurements with field effect transistors with these AfFtn-AA/BLG surfaces show hysteresis with two Dirac peaks. One peak at a gate voltage Vg = 35 V is associated with pristine BLG, while the second peak at Vg = 5 V results from local doping by ferritin. This charge trapping at the biomolecular length-scale offers a straightforward and non-destructive method to alter the local electronic structure of BLG.

Investigating plant structure is fundamental in botanical science and provides crucial knowledge for the theories of plant evolution, ecophysiology and for the biotechnological practices. Modern plant anatomy often targets the formation, localization and characterization of cellulosic, lignified or suberized cell walls. While classical methods developed in the 1960s are still popular, recent innovations in tissue preparation, fluorescence staining and microscopy equipment offer advantages to the traditional practices for investigation of the complex lignocellulosic walls. Our goal is to enhance the productivity and quality of microscopy work by focusing on quick and cost-effective preparation of thick sections or plant specimen surfaces and efficient use of direct fluorescent stains. We discuss popular histochemical microscopy techniques for visualization of cell walls, such as autofluorescence or staining with calcofluor, Congo red (CR), fluorol yellow (FY) and safranin, and provide detailed descriptions of our own approaches and protocols. Autofluorescence of lignin in combination with CR and FY staining can clearly differentiate between lignified, suberized and unlignified cell walls in root and stem tissues. Glycerol can serve as an effective clearing medium as well as the carrier of FY for staining of suberin and lipids allowing for observation of thick histological preparations. Three-dimensional (3D) imaging of all cell types together with chemical information by wide-field fluorescence or confocal laser scanning microscopy (CLSM) was achieved., Investigating plant structure is fundamental in botanical science. Across disciplines, such as plant development, ecophysiology and biotechnology, particular interest is focused on the complex structure of lignocellulosic walls. We review the recent innovations in tissue preparation and fluorescence staining for lignin and suberin. We demonstrate simple and cost-effective protocols for preparation of plant samples for microscopy using hand-cut sections and clearing with glycerol. Autofluorescence of lignin in combination with direct stains such as Congo red and fluorol yellow can clearly differentiate between lignified, suberized and unlignified cell wall domains.

Endogenous brain proteins can recognize the toxic oligomers of amyloid-β (Aβ) peptides implicated in Alzheimer’s disease (AD) and interact with them to prevent their aggregation. Lipocalin-type Prostaglandin D Synthase (L-PGDS) is a major Aβ-chaperone protein in the human cerebrospinal fluid. Here we demonstrate that L-PGDS detects amyloids in diseased mouse brain. Conjugation of L-PGDS with magnetic nanoparticles enhanced the contrast for magnetic resonance imaging. We conjugated the L-PGDS protein with ferritin nanocages to detect amyloids in the AD mouse model brain. We show here that the conjugates administered through intraventricular injections co-localize with amyloids in the mouse brain. These conjugates can target the brain regions through non-invasive intranasal administration, as shown in healthy mice. These conjugates can inhibit the aggregation of amyloids in vitro and show potential neuroprotective function by breaking down the mature amyloid fibrils.

Synthetic biology has focused on engineering genetic modules that operate orthogonally from the host cells. A synthetic biological module, however, can be designed to reprogram the host proteome, which in turn enhances the function of the synthetic module. Here, we apply this holistic synthetic biology concept to the engineering of cell-free systems by exploiting the crosstalk between metabolic networks in cells, leading to a protein environment more favorable for protein synthesis. Specifically, we show that local modules expressing translation machinery can reprogram the bacterial proteome, changing the expression levels of more than 700 proteins. The resultant feedback generates a cell-free system that can synthesize fluorescent reporters, protein nanocages, and the gene-editing nuclease Cas9, with up to 5-fold higher expression level than classical cell-free systems. Our work demonstrates a holistic approach that integrates synthetic and systems biology concepts to achieve outcomes not possible by only local, orthogonal circuits., Synthetic biological modules can be used to reprogram host proteomes, which in turn enhance the function of the synthetic modules. The authors use this holistic synthetic biology approach to engineer a more favorable environment for cell-free protein synthesis.