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- ItemHuman spermbots for patient-representative 3D ovarian cancer cell treatment(Cambridge : RSC Publ., 2020) Xu, Haifeng; Medina-Sánchez, Mariana; Zhang, Wunan; Seaton, Melanie P. H.; Brison, Daniel R.; Edmondson, Richard J.; Taylor, Stephen S.; Nelson, Louisa; Zeng, Kang; Bagley, Steven; Ribeiro, Carla; Restrepo, Lina P.; Lucena, Elkin; Schmidt, Christine K.; Schmidt, Oliver G.Cellular micromotors are attractive for locally delivering high concentrations of drug, and targeting hard-to-reach disease sites such as cervical cancer and early ovarian cancer lesions by non-invasive means. Spermatozoa are highly efficient micromotors perfectly adapted to traveling up the female reproductive system. Indeed, bovine sperm-based micromotors have shown potential to carry drugs toward gynecological cancers. However, due to major differences in the molecular make-up of bovine and human sperm, a key translational bottleneck for bringing this technology closer to the clinic is to transfer this concept to human material. Here, we successfully load human sperm with Doxorubicin (DOX) and perform treatment of 3D cervical cancer and patient-representative ovarian cancer cell cultures, resulting in strong anticancer cell effects. Additionally, we define the subcellular localization of the chemotherapeutic drug within human sperm, using high-resolution optical microscopy. We also assess drug effects on sperm motility and viability over time, employing sperm samples from healthy donors as well as assisted reproduction patients. Finally, we demonstrate guidance and release of human drug-loaded sperm onto cancer tissues using magnetic microcaps, and show the sperm microcap loaded with a second anticancer drug, camptothecin (CPT), which unlike DOX is not suitable for directly loading into sperm due to its hydrophobic nature. This co-drug delivery approach opens up novel targeted combinatorial drug therapies for future applications. © 2020 The Royal Society of Chemistry.
- ItemIntegrated molecular diode as 10 MHz half-wave rectifier based on an organic nanostructure heterojunction([London] : Nature Publishing Group UK, 2020) Li, Tianming; Bandari, Vineeth Kumar; Hantusch, Martin; Xin, Jianhui; Kuhrt, Robert; Ravishankar, Rachappa; Xu, Longqian; Zhang, Jidong; Knupfer, Martin; Zhu, Feng; Yan, Donghang; Schmidt, Oliver G.Considerable efforts have been made to realize nanoscale diodes based on single molecules or molecular ensembles for implementing the concept of molecular electronics. However, so far, functional molecular diodes have only been demonstrated in the very low alternating current frequency regime, which is partially due to their extremely low conductance and the poor degree of device integration. Here, we report about fully integrated rectifiers with microtubular soft-contacts, which are based on a molecularly thin organic heterojunction and are able to convert alternating current with a frequency of up to 10 MHz. The unidirectional current behavior of our devices originates mainly from the intrinsically different surfaces of the bottom planar and top microtubular Au electrodes while the excellent high frequency response benefits from the charge accumulation in the phthalocyanine molecular heterojunction, which not only improves the charge injection but also increases the carrier density.
- ItemIRONSperm: Sperm-templated soft magnetic microrobots(Washington, DC : American Association for the Advancement of Science, 2020) Magdanz, Veronika; Khalil, Islam S.M.; Simmchen, Juliane; Furtado, Guilherme P.; Mohanty, Sumit; Gebauer, Johannes; Xu, Haifeng; Klingner, Anke; Aziz, Azaam; Medina-Sánchez, Mariana; Schmidt, Oliver G.; Misra, SarthakWe develop biohybrid magnetic microrobots by electrostatic self-assembly of nonmotile sperm cells and magnetic nanoparticles. Incorporating a biological entity into microrobots entails many functional advantages beyond shape templating, such as the facile uptake of chemotherapeutic agents to achieve targeted drug delivery. We present a single-step electrostatic self-assembly technique to fabricate IRONSperms, soft magnetic microswimmers that emulate the motion of motile sperm cells. Our experiments and theoretical predictions show that the swimming speed of IRONSperms exceeds 0.2 body length/s (6.8 ± 4.1 µm/s) at an actuation frequency of 8 Hz and precision angle of 45°. We demonstrate that the nanoparticle coating increases the acoustic impedance of the sperm cells and enables localization of clusters of IRONSperm using ultrasound feedback. We also confirm the biocompatibility and drug loading ability of these microrobots, and their promise as biocompatible, controllable, and detectable biohybrid tools for in vivo targeted therapy.
- ItemSteering Directional Light Emission and Mode Chirality through Postshaping of Cavity Geometry(Hoboke, NJ : Wiley, 2020) Wang, Jiawei; Tang, Min; Yang, Yue-De; Yin, Yin; Chen, Yan; Saggau, Christian Niclaas; Zhu, Minshen; Yuan, Xiaobo; Karnaushenko, Dmitriy; Huang, Yong-Zhen; Ma, Libo; Schmidt, Oliver G.Dielectric optical microcavities have been explored as an excellent platform to manipulate the light flow and investigate non‐Hermitian physics in open optical systems. For whispering gallery mode optical microcavities, modifying the rotational symmetry is highly desirable for intriguing phenomena such as degenerated chiral modes and directional light emission. However, for the state‐of‐the‐art approaches, namely deforming the cavity geometry by precision lithography or introducing local scatterers near the cavity boundary via micromanipulation, there is a lack of flexibility in fine‐adjusting of chiral symmetry and far‐field emission direction. Here, precise engineering of cavity boundary using electron‐beam‐induced deposition is reported based on rolled‐up nanomembrane‐enabled spiral‐shaped microcavities. The deformation of outer boundary results in delicate tailoring of asymmetric backscattering between the outer and inner rolling edges, and hence deterministically strong mode chirality. Besides, the crescent‐shaped high‐index nanocap leads to modified light tunneling channels and inflected far‐field emission angle. It is envisioned that such a localized deposition‐assisted technique for adjusting the structural deformation of 3D optical microcavities will be highly useful for understanding rich insights in non‐Hermitian photonics and unfolding exotic properties on lasing, sensing, and cavity quantum electrodynamics.
- ItemSperm-Driven Micromotors Moving in Oviduct Fluid and Viscoelastic Media(Weinheim : Wiley-VCH, 2020) Striggow, Friedrich; Medina-Sánchez, Mariana; Auernhammer, Günter K.; Magdanz, Veronika; Friedrich, Benjamin M.; Schmidt, Oliver G.Biohybrid micromotors propelled by motile cells are fascinating entities for autonomous biomedical operations on the microscale. Their operation under physiological conditions, including highly viscous environments, is an essential prerequisite to be translated to in vivo settings. In this work, a sperm-driven microswimmer, referred to as a spermbot, is demonstrated to operate in oviduct fluid in vitro. The viscoelastic properties of bovine oviduct fluid (BOF), one of the fluids that sperm cells encounter on their way to the oocyte, are first characterized using passive microrheology. This allows to design an artificial oviduct fluid to match the rheological properties of oviduct fluid for further experiments. Sperm motion is analyzed and it is confirmed that kinetic parameters match in real and artificial oviduct fluids, respectively. It is demonstrated that sperm cells can efficiently couple to magnetic microtubes and propel them forward in media of different viscosities and in BOF. The flagellar beat pattern of coupled as well as of free sperm cells is investigated, revealing an alteration on the regular flagellar beat, presenting an on–off behavior caused by the additional load of the microtube. Finally, a new microcap design is proposed to improve the overall performance of the spermbot in complex biofluids. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemEngineering microrobots for targeted cancer therapies from a medical perspective(Berlin : Springer Nature, 2020) Schmidt, Christine K.; Medina-Sánchez, Mariana; Edmondson, Richard J.; Schmidt, Oliver G.Systemic chemotherapy remains the backbone of many cancer treatments. Due to its untargeted nature and the severe side effects it can cause, numerous nanomedicine approaches have been developed to overcome these issues. However, targeted delivery of therapeutics remains challenging. Engineering microrobots is increasingly receiving attention in this regard. Their functionalities, particularly their motility, allow microrobots to penetrate tissues and reach cancers more efficiently. Here, we highlight how different microrobots, ranging from tailor-made motile bacteria and tiny bubble-propelled microengines to hybrid spermbots, can be engineered to integrate sophisticated features optimised for precision-targeting of a wide range of cancers. Towards this, we highlight the importance of integrating clinicians, the public and cancer patients early on in the development of these novel technologies.
- ItemQuantum dot-based broadband optical antenna for efficient extraction of single photons in the telecom O-band(Washington, DC : The Optical Society, 2020) Yang, Jingzhong; Nawrath, Cornelius; Keil, Robert; Joos, Raphael; Zhang, Xi; Höfer, Bianca; Chen, Yan; Zopf, Michael; Jetter, Michael; Portalupi, Simone Luca; Ding, Fei; Michler, Peter; Schmidt, Oliver G.Long-distance fiber-based quantum communication relies on efficient non-classical light sources operating at telecommunication wavelengths. Semiconductor quantum dots are promising candidates for on-demand generation of single photons and entangled photon pairs for such applications. However, their brightness is strongly limited due to total internal reflection at the semiconductor/vacuum interface. Here we overcome this limitation using a dielectric antenna structure. The non-classical light source consists of a gallium phosphide solid immersion lens in combination with a quantum dot nanomembrane emitting single photons in the telecom O-band. With this device, the photon extraction is strongly increased in a broad spectral range. A brightness of 17% (numerical aperture of 0.6) is obtained experimentally, with a single photon purity of 𝑔(2)(0)=0.049±0.02 at saturation power. This brings the practical implementation of quantum communication networks one step closer.
- ItemAdvanced Hybrid GaN/ZnO Nanoarchitectured Microtubes for Fluorescent Micromotors Driven by UV Light(Weinheim : Wiley-VCH, 2020) Wolff, Niklas; Ciobanu, Vladimir; Enachi, Mihail; Kamp, Marius; Braniste, Tudor; Duppel, Viola; Shree, Sindu; Raevschi, Simion; Medina-Sánchez, Mariana; Adelung, Rainer; Schmidt, Oliver G.; Kienle, Lorenz; Tiginyanu, IonThe development of functional microstructures with designed hierarchical and complex morphologies and large free active surfaces offers new potential for improvement of the pristine microstructures properties by the synergistic combination of microscopic as well as nanoscopic effects. In this contribution, dedicated methods of transmission electron microscopy (TEM) including tomography are used to characterize the complex hierarchically structured hybrid GaN/ZnO:Au microtubes containing a dense nanowire network on their interior. The presence of an epitaxially stabilized and chemically extremely stable ultrathin layer of ZnO on the inner wall of the produced GaN microtubes is evidenced. Gold nanoparticles initially trigger the catalytic growth of solid solution phase (Ga1– xZnx)(N1– xOx) nanowires into the interior space of the microtube, which are found to be terminated by AuGa-alloy nanodots coated in a shell of amorphous GaOx species after the hydride vapor phase epitaxy process. The structural characterization suggests that this hierarchical design of GaN/ZnO microtubes could offer the potential to exhibit improved photocatalytic properties, which are initially demonstrated under UV light irradiation. As a proof of concept, the produced microtubes are used as photocatalytic micromotors in the presence of hydrogen peroxide solution with luminescent properties, which are appealing for future environmental applications and active matter fundamental studies. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemStress‐Actuated Spiral Microelectrode for High‐Performance Lithium‐Ion Microbatteries(2020) Tang, Hongmei; Karnaushenko, Dmitriy D.; Neu, Volker; Gabler, Felix; Wang, Sitao; Liu, Lixiang; Li, Yang; Wang, Jiawei; Zhu, Minshen; Schmidt, Oliver G.Miniaturization of batteries lags behind the success of modern electronic devices. Neither the device volume nor the energy density of microbatteries meets the requirement of microscale electronic devices. The main limitation for pushing the energy density of microbatteries arises from the low mass loading of active materials. However, merely pushing the mass loading through increased electrode thickness is accompanied by the long charge transfer pathway and inferior mechanical properties for long‐term operation. Here, a new spiral microelectrode upon stress‐actuation accomplishes high mass loading but short charge transfer pathways. At a small footprint area of around 1 mm2, a 21‐fold increase of the mass loading is achieved while featuring fast charge transfer at the nanoscale. The spiral microelectrode delivers a maximum area capacity of 1053 µAh cm−2 with a retention of 67% over 50 cycles. Moreover, the energy density of the cylinder microbattery using the spiral microelectrode as the anode reaches 12.6 mWh cm−3 at an ultrasmall volume of 3 mm3. In terms of the device volume and energy density, the cylinder microbattery outperforms most of the current microbattery technologies, and hence provides a new strategy to develop high‐performance microbatteries that can be integrated with miniaturized electronic devices.