Biology subjects

Heuer-Jungemann, A.

Publications and source records attributed to Heuer-Jungemann, A..

9 recordsLinked to original sources

bioRxiv2025

Customizable silicification of DNA origami nanostructures

The silicification of DNA origami nanostructures offers a powerful strategy for enhancing their mechanical stability and resistivity against detrimental environmental conditions. In the past years, several studies have investigated different aspects of the silica coating procedure, leading to several different silicification protocols. Until now, the silica coating generally served as a protective layer or as the base for the further deposition of inorganic materials. However, it did not carry any additional functionality itself. Here, we present two different approaches for the customization of the silica coating on DNA origami nanostructures. Firstly, we developed a custom synthesized silica precursor carrying a fluorescein molecule to endow the silica coating of both DNA origami monomers and crystals with fluorescence and show the applicability of this novel silicification for the stabilization and tracking of DNA origami nanostructures intracellularly. Secondly, we employ a silica precursor containing a disulfide bridge to develop a silica coating that is dissolvable in a reducing environment. We anticipate that the results presented in this study will expand the toolbox of silicification in DNA nanotechnology and will further pave the way towards applications in drug delivery and material science.

biophysics↗

bioRxiv2025

Effects of DNA Origami-Based Nanoagent Design on Apoptosis Induction in a Large 3D Spheroid Model

The extrinsic activation of programmed cell death by FasR/CD95 is a promising minimally invasive strategy for cancer treatment. This can be leveraged using high-precision nanoscale therapeutics: Utilizing DNA origami for precise Fas ligand (FasL) presentation resulted in over 100 times more potent apoptosis induction in single cells. However, treating large, solid tumors poses challenges for DNA origami-based therapeutics, including drug distribution and altered cellular behavior. Here, we addressed these challenges using a 3D spheroid model. First, we assessed DNA origamis ability to penetrate tumor tissue, finding that penetration is influenced by the DNA origami size rather its structural flexibility. Second, we evaluated the apoptosis induction efficacy by DNA origami-FasL nanoagents within the spheroid model. The most potent nanoagents were able to completely eradicate all cells in the spheroid. Results indicated that apoptosis induction depended strongly on FasL attachment strategy rather than DNA origami design. Notably, only a rigid neutravidin linker for FasL attachment, rather than a flexible dsDNA linker, halted spheroid growth and fully eradicated all cancer cells. This study offers critical insights into designing DNA-based therapeutics for complex cellular environments and significantly advances DNA origami nanotherapeutic development, highlighting the impact of nanoagent design on cell fate decisions.

bioengineering↗

bioRxiv2024

Monitoring the Coating of Single DNA Origami Nanostructures with a Molecular Fluorescence Lifetime Sensor

The high functionality of DNA nanostructures makes them a promising tool for biomedical applications, their intrinsic instability under application-relevant conditions, still remains challenging. Protective coating of DNA nanostructures with materials like silica or cationic polymers has evolved as a simple, yet powerful strategy to improve their stability even under extreme conditions. While over time, various materials and protocols have been developed, the characterization and quality assessment of the coating is either time consuming, highly invasive or lacks detailed insights on single nanostructures. Here, we introduce a cyanine dye based molecular sensor designed to non-invasively probe the coating of DNA origami by either a cationic polymer or by silica, in real-time and on a single nanostructure level. The cyanine dye reports changes in its local environment upon coating via increased fluorescence lifetime induced by steric restriction and water exclusion. Exploiting the addressability of DNA origami, the molecular sensor can be placed at selected positions to probe the coating layer with nanometer precision. We demonstrate the reversibility of the sensor and use it to study the stability of the different coatings in degrading conditions. To showcase the potential for correlative studies, we combine the molecular fluorescence lifetime sensor with DNA PAINT super-resolution imaging to investigate coating and structural integrity as well as preserved addressability of DNA nanostructures. The reported sensor presents a valuable tool to probe the coating of DNA nanodevices in complex biochemical environments in real-time and at the single nanosensor level and aids the development of novel stabilization strategies.

biophysics↗

bioRxiv2024

High yield purification of an Isoleucine zipper modified CD95 Ligand with either biotin or DNA-oligomer binding domain for efficient Cell Apoptosis Induction

BackgroundCluster of differentiation 95 (CD95/Fas/Apo1) as part of the Tumor-necrosis factor (TNF) receptor family is a prototypic trigger of the extrinsic apoptotic pathway and its activation by the trimeric ligand CD95L is of high interest for anticancer therapy. However, CD95L, when presented in solution, exhibits a low efficiency to induce apoptosis signaling in human cells. ResultsHere, we design a recombinant CD95L exhibiting an isoleucine zipper (IZ) motif at the N-terminus for stabilization of the trimerized CD95L and demonstrate its high apoptosis induction efficiency. A cysteine amino acid fused behind the IZ is further used as a versatile coupling site for bionanotechnological applications or for the development of biomedical assays. A fast, cheap, and high-yield production of CD95L via the HEK293T secretory expression system is presented, along with CD95L affinity purification and functionalization. We verified the biological activity of the purified protein and identified a stabilized trimeric CD95L structure as the most potent inducer of apoptosis signaling. ConclusionsThe workflow and the findings reported here will streamline a wide array of future low- or high-throughput TNF-ligand screens, and their modification towards improving apoptosis induction efficiency and anticancer therapy.

cell biology↗

bioRxiv2024

Compliant DNA Origami Nanoactuators as Size-Selective Nanopores

Biological nanopores crucially control the import and export of biomolecules across lipid membranes in cells. They have found widespread use in biophysics and biotechnology, where their typically narrow, fixed diameters enable selective transport of ions and small molecules as well as DNA and peptides for sequencing applications. Yet, due to their small channel sizes, they preclude the passage of large macromolecules, e.g., therapeutics. Here, we harness the unique combined properties of DNA origami nanotechnology, machine-inspired design, and synthetic biology, to present a structurally reconfigurable DNA origami MechanoPore (MP) that features a lumen that is tuneable in size through molecular triggers. Controllable switching of MPs between three stable states is confirmed by 3D-DNA-PAINT super-resolution imaging and through dye-influx assays, after reconstitution of the large MPs in the membrane of liposomes via an inverted-emulsion cDICE technique. Confocal imaging of transmembrane transport shows size-selective behaviour with adjustable thresholds. Importantly, the conformational changes are fully reversible, attesting to the robust mechanical switching that overcomes pressure from the surrounding lipid molecules. These MPs advance nanopore technology, offering functional nanostructures that can be tuned on-demand - thereby impacting fields as diverse as drug-delivery, biomolecule sorting and sensing, as well as bottom-up synthetic biology.

biophysics↗

bioRxiv2023

Fully addressable, designer superstructures assembled from a single modular DNA origami

Intricate self-organization is essential in many biological processes, underpinning vital functions and interactions. In an effort to mimic such processes, synthetic biology aims to engineer dynamic structures with controllable functions using nanotechnological tools. A key requirement of engineered building blocks is the ability to assemble and disassemble hierarchically with precision. Using the DNA origami technique, we here present the moDON, a modular DNA origami nanostructure, which is capable of assembling into almost 20 000 diverse monomers, forming complex and controlled superstructures in three dimensions. While shape and addressability of DNA origami are nearly arbitrary, its overall size is limited by the scaffold size. Previous methods of extending the size of DNA origami (e.g. hierarchical assembly, modified scaffolds, etc.), either led to loss over control of shape and addressability beyond monomers or to proportionally increased cost and design effort. With the moDON we were able to overcome both issues. The modular design combines xy- and z-plane assembly methods, enabling the construction of finite and periodic structures beyond 1 GDa. We demonstrate xy-z orthogonality, by enabling controlled selective or parallel assembly and disassembly via distinct orthogonal triggers. The kinetic profile of assembly and disassembly aligns with biological time scales, paving the way for applications in dynamic nanomachinery and advanced biomaterials. Finally, we showcase the conjugation of gold nanoparticles to specific positions within superstructures, underscoring the efficacy of this approach for creating intricate and orthogonal nanoscale architectures with preserved site-specific addressability. The moDON thus offers an efficient, cost-effective solution for constructing large, precisely organized, and fully addressable structures with vast potential in synthetic cellular systems design.

biophysics↗

bioRxiv2022

Full site-specific addressability in DNA origami-templated silica nanostructures

DNA nanotechnology allows for the fabrication of nano-meter-sized objects with high precision and selective addressability as a result of the programmable hybridization of complementary DNA strands. Such structures can template the formation of other materials, including metals and complex silica nanostructures, where the silica shell simultaneously acts to protect the DNA from external detrimental factors. However, the formation of silica nanostructures with site-specific addressability has thus far not been explored. Here we show that silica nanostructures templated by DNA origami remain addressable for post silicification modification with guest molecules even if the silica shell measures several nm in thickness. We used the conjugation of fluorescently labelled oligonucleotides to different silicified DNA origami structures carrying a complementary ssDNA handle as well as DNA PAINT super-resolution imaging to show that ssDNA handles remain unsilicified and thus ensure retained addressability. We also demonstrate that not only handles, but also ssDNA scaffold segments within a DNA origami nanostructure remain accessible, allowing for the formation of dynamic silica nanostructures. Finally we demonstrate the power of this approach by forming 3D DNA origami crystals from silicified monomers. Our results thus present a fully site-specifically addressable silica nanostructure with complete control over size and shape.

biophysics↗

bioRxiv2020

Nanoscale Organization of FasL on DNA Origami as a Versatile Platform to Tune Apoptosis Signaling in Cells

Nanoscale probes with fine-tunable properties are of key interest in cell biology and nanomedicine to elucidate and eventually control signaling processes in cells. A critical, still challenging issue is to conjugate these probes with molecules in a number- and spatially-controlled manner. Here, DNA origami-based nanoagents as nanometer precise scaffolds presenting Fas ligand (FasL) in well-defined arrangements to cells are reported. These nanoagents activate receptor molecules in the plasma membrane initiating apoptosis signaling in cells. Signaling for apoptosis depends sensitively on FasL geometry: fastest time-to-death kinetics are obtained for FasL nanoagents representing predicted structure models of hexagonal receptor ordering with 10 nm inter-molecular spacing. Slower kinetics are observed for one to two FasL on DNA origami or FasL coupled with higher flexibility. Nanoagents with FasL arranged in hexagons with small (5 nm) and large (30 nm) spacing impede signal transduction. Moreover, for predicted hexagonal FasL nanoagents, signaling efficiency is faster and 100× higher compared to naturally occurring soluble FasL. Incubation of the FasL-origami nanoagent in solution exhibited an EC50 value of only 90 pM. These studies present DNA origami as versatile signaling platforms to probe the significance of molecular number and nanoscale ordering for signal initiation in cells.Competing Interest StatementThe authors have declared no competing interest.View Full Text

biophysics↗

bioRxiv2020

Unraveling the interaction between doxorubicin and DNA origami nanostructures for customizable chemotherapeutic drug release

Doxorubicin (DOX) is a common drug in cancer chemotherapy, and its high DNA-binding affinity can be harnessed in preparing DOX-loaded DNA nanostructures for targeted delivery and therapeutics. Although DOX has been widely studied, the existing literature of DOX-loaded DNA-carriers remains limited and incoherent. Here, based on an in-depth spectroscopic analysis, we characterize and optimize the DOX loading into different 2D and 3D scaffolded DNA origami nanostructures (DONs). In our experimental conditions, all DONs show similar DOX binding capacities (one DOX molecule per two to three base pairs), and the binding equilibrium is reached within seconds, remarkably faster than previously acknowledged. To characterize drug release profiles, DON degradation and DOX release from the complexes upon DNase I digestion was studied. For the employed DONs, the relative doses (DOX molecules released per unit time) may vary by two orders of magnitude depending on the DON superstructure. In addition, we identify DOX aggregation mechanisms and spectral changes linked to pH, magnesium, and DOX concentration. These features have been largely ignored in experimenting with DNA nanostructures, but are probably the major sources of the incoherence of the experimental results so far. Therefore, we believe this work can act as a guide to tailoring the release profiles and developing better drug delivery systems based on DNA-carriers.

biochemistry↗