Jeewon Lee

Cancer-associated microRNAs are promising biomarkers for early cancer diagnosis. However, current microRNA detections – which are based on polymerase chain reaction, microarray analysis, Raman scattering, or various electrochemical assays – rely on multi-step analysis including amplification of microRNA and/or read-out signals, often causing inaccuracy despite using elaborate instruments, which remains a major challenge. Here, we describe an RNaseH1-dependent, amplification-free detection of microRNAs, which is based on Förster resonance energy transfer (FRET) between donor (single-stranded DNA probe (ssDNA)-spiked, green fluorescent nanocage) and acceptor (RNaseH1-linked, orange fluorescent protein) and enables reliable cancer diagnosis with high accuracy for human lung and gastric cancer patients and healthy donors by directly quantifying serum microRNA targets. Notably, unlike traditional ensemble FRET, this FRET platform senses molecular interactions between ssDNA and miRNAs and conformational changes of their hybrid helices and thus differentiates even a single-base mismatch, which holds significant promise for reliable, clinical cancer diagnosis.

A common challenge in nanotechnology is synthesizing nanomaterials with well‐defined structures. In particular, it remains a major unresolved challenge to precisely regulate the structure and function of protein nanomaterials, which are structurally diverse, highly ordered, and complex and offer an innovative means that enables a high performance in various nanodevices, which is rarely achievable with other nanomaterials. Here an innovative approach is proposed to fabricating multi‐dimensional (0‐ to 3D) protein nanostructures with functional and structural specialties via molecular‐level regulation. This approach is based on a stable, consistent, anisotropic self‐assembly of Tobacco mosaic virus (TMV) coat protein‐derived engineered building blocks where genetically added tryptophan residues are externally tailored. The unique structural characteristics of each nanostructure above are demonstrated in detail through various analyses (electron microscopy, atomic force microscopy, dynamic light scattering, and small‐angle X‐ray scattering) and further investigated through molecular dynamics simulations, indicating that this control, anisotropic, and molecular assembly‐based approach to regulating protein nanostructures holds great potential for customizing a variety of nanomaterials with unique functions and structures.

Soluble methane monooxygenase (sMMO) oxidizes a wide range of carbon feedstocks (C1 to C8) directly using intracellular NADH and is a useful means in developing green routes for industrial manufacturing of chemicals. However, the high-throughput biosynthesis of active recombinant sMMO and the ensuing catalytic oxidation have so far been unsuccessful due to the structural and functional complexity of sMMO, comprised of three functionally complementary components, which remains a major challenge for its industrial applications. Here we develop a catalytically active miniature of sMMO (mini-sMMO), with a turnover frequency of 0.32 s⁻¹, through an optimal reassembly of minimal and modified components of sMMO on catalytically inert and stable apoferritin scaffold. We characterise the molecular characteristics in detail through in silico and experimental analyses and verifications. Notably, in-situ methanol production in a high-cell-density culture of mini-sMMO-expressing recombinant Escherichia coli resulted in higher yield and productivity (~ 3.0 g/L and 0.11 g/L/h, respectively) compared to traditional methanotrophic production.

Soluble methane monooxygenase (sMMO) oxidizes a wide range of carbon feedstocks (C1 to C8) directly using intracellular NADH and is a useful means in developing green routes for industrial manufacturing of chemicals; however, the high-throughput biosynthesis of active recombinant sMMO and the ensuing catalytic oxidation have so far been unsuccessful due to the structural and functional complexity of sMMO, comprised of functionally complementary, three enzyme components, which remains a major challenge for its industrial applications. Here we developed a catalytically active miniature of sMMO (mini-sMMO) through an optimal reassembly of minimal and modified components of sMMO on catalytically inert and stable apoferritin scaffold, with demonstrating the molecular characteristics in detail through in silico and experimental analyses and verifications. Notably, the in-situ methanol production in the high-cell-density culture of mini-sMMO-expressing recombinant Escherichia coli resulted in a remarkably higher productivity compared to the traditional methanotrophic production.

Composite solid electrolytes (CSEs) are newly emerging components for all‐solid‐state Li‐metal batteries owing to their excellent processability and compatibility with the electrodes. Moreover, the ionic conductivity of the CSEs is one order of magnitude higher than the solid polymer electrolytes (SPEs) by incorporation of inorganic fillers into SPEs. However, their advancement has come to a standstill owing to unclear Li‐ion conduction mechanism and pathway. Herein, the dominating effect of the oxygen vacancy (O_vac) in the inorganic filler on the ionic conductivity of CSEs is demonstrated via Li‐ion‐conducting percolation network model. Based on density functional theory, indium tin oxide nanoparticles (ITO NPs) are selected as inorganic filler to determine the effect of O_vac on the ionic conductivity of the CSEs. Owing to the fast Li‐ion conduction through the O_vac inducing percolation network on ITO NP–polymer interface, LiFePO₄/CSE/Li cells using CSEs exhibit a remarkable capacity in long‐term cycling (154 mAh g⁻¹ at 0.5C after 700 cycles). Moreover, by modifying the O_vac concentration of ITO NPs via UV‐ozone oxygen‐vacancy modification, the ionic conductivity dependence of the CSEs on the surface O_vac from the inorganic filler is directly verified.

Although a variety of urinary cancer markers are available for in vitro diagnosis, inherent problems of urine environment—containing various inorganic/organic ions/molecules that vary in concentration over a 20‐fold range or more and significantly attenuate antibody avidity for markers—render conventional immunoassays unsuitable, remaining unresolved and a major challenge. Here we developed a 3D‐plus‐3D (3p3) immunoassay method, based on a single‐step urinary marker detection by 3D‐antibody probes, which are free of steric hindrance and capable of omnidirectional capture of markers in a 3D solution. The 3p3 immunoassay showed an excellent performance in the diagnosis of prostate cancer (PCa) through detecting PCa‐specific urinary engrailed‐2 protein, demonstrating 100% sensitivity and 100% specificity with the urine specimens of PCa‐related and other related disease patients and healthy individuals. This innovative approach holds a great potential in opening up a novel clinical route for precise in vitro cancer diagnosis and also pushing urine immunoassay closer to more widespread adoption.

Cancer chemotherapeutic drugs such as doxorubicin, mitomycin C, and gemcitabine, which are mostly small synthetic molecules, are still clinically useful for cancer treatment. However, despite considerable therapeutic efficacy, severe toxicity‐associated problems, which are mainly caused by the non‐specific mode of action such as chromosomal DNA damage and interference in the DNA replication even in normal cells, remain unresolved and a major challenge for safer and thus more widespread adoption of chemotherapy. Herein, an innovative platform is developed through beneficially integrating core peptide units into highly‐ordered, stable, and flexibly guest‐adaptable structure of apoferritin, which simultaneously fulfills high‐capacity loading of chemotherapeutic drugs compared with the case of FDA‐approved antibody‐drug conjugates, efficient drug targeting to cancer cells, and cancer cell‐specific drug release and activation. This approach dramatically reduces drug toxicity to normal cells, significantly enhances efficacy in in vivo cancer treatment without toxicity to normal organs of mice, and thus is expected to open up a novel clinical route to break through the limits of current cancer chemotherapy.