Center for Nanoscience and Nanotechnology

HypothesisThere is a growing interest in designing superhydrophobic materials for many applications including self-clean surfaces, separation systems, and antifouling solutions. Peptides and amino acids offer attractive building blocks for these materials since they are biocompatible and biodegradable and can self-assemble into complex ordered structures.Experiments and SimulationsWe designed a self-standing superhydrophobic material through the self-assembly of an individual functionalized aromatic amino acid, Cbz-Phe(4F). The self-assembly of Cbz-Phe(4F) was investigated by experimental and computational methods. Moreover, when drop-casted three times on a solid support, it formed a self-standing superhydrophobic material. The mechanical properties and chemical stability of this self-standing superhydrophobic material were demonstrated.FindingsThe designed Cbz-Phe(4F) self-assembled into …

In this talk we discuss the limitations and the potential of metalenses, and demonstrate several results where the limitations are being circumvent by applying a hybrid approach of metalens and computational imaging.

Mechanisms for Electric Field Induced Color Change in Coupled Colloidal Quantum Dot Molecules Revealed by Low Temperatures Single Particle Spectroscopy EN LOGIN REGISTER All data generated by the account on the platform will be deleted after logout. Close Save Journal Home > Just Accepted Nano Research Research Article | Just accepted | Available online: 21 June 2024 Mechanisms for Electric Field Induced Color Change in Coupled Colloidal Quantum Dot Molecules Revealed by Low Temperatures Single Particle Spectroscopy Show Author's Information Hide Author's Information Yossef E. Panfil 1 , † , Adar Levi 1 , Somnath Koley 1 , †† , Einav Scharf 1 , Yonatan Ossia 1 , Uri Banin 1 ( ) 1 Institute of Chemistry and the center for nanoscience and nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel † Present address: Quantum Engineering Laboratory, the Department of …

Industrial pollutants, including perfluoroalkyl and polyfluoroalkyl substances (PFASs), pose serious health and environmental risks. Time-consuming and expensive traditional detection techniques, including liquid chromatography-mass spectrometry, impede prompt field examination. PFASense attempts to address this problem by the development of cost-effective, dependable, and sustainable electrochemical techniques for continuous PFAS evaluation in contaminated aquatic environments. The proposed approach combines a pretreatment phase employing nanofiltration membranes to remove interfering impurities, chemometric arraybased analysis, as well as bacteria-and yeast-based whole cell biosensors. The sensors are examined in complex aqueous matrices, such as contaminated ground water, and mathematical models are employed for perfluorooctane sulfonic acid (PFOS) quantification. To date, we have demonstrated preliminary limits of PFOS detection in buffer of 151±53 nM and 53.1±19.0 nM, employing fluorinated and hydrophobic modified electrodes, respectively. We plan to eventually integrate the complementary PFASense technologies into a portable fluidic device for continuous PFAS monitoring.

We experimentally demonstrate a new electro-optic SRAM element fully CMOS compatible. Inspired by the Esaki diode, presenting negative differential resistance (NDR), we designed a new type of NDR diode based on a horizontal PN junction and a region with higher acceptor concentration, P+, in silicon. We embedded the new NDR into a photonic micro-ring resonator to enable a bistable device with electrical and optical readout capabilities. Our device is remarkable for its simplicity, CMOS compatibility and its low power consumption around the nanowatt, but it’s also an important steppingstone on the way to new nonlinear electro-optic and neuromorphic computing structures.

We experimentally demonstrate a Huygens metasurface in the visible regime utilizing Silicon rich Nitride (SRN). Offering high refractive index and CMOS compatibility, SRN is an outstanding candidate to replace the widely used TiO2.

Metallic transition metal dichalcogenides (TMDs), consisting of H-NbSe, H-NbS, H-TaSe and H-TaS, remain superconducting down to a thickness of a single layer. In these materials, thickness affects a variety of properties, including Ising protection, two-band superconductivity, and the critical temperature , which decreases for the Nb-based, and increases for the Ta-based materials. This contradicting trend is puzzling, and has precluded the development of a unified theory. We approach the question of thickness-evolution of and the superconducting gap by measuring high-resolution tunneling spectra in TaS-based stacked devices. Our measurements allow for simultaneous evaluation of , , and the upper critical field . The latter, we find, is strongly enhanced towards the single-layer limit, following a proportionality ratio. Our main finding is that the same ratio holds for the entire family of metallic TMDs: TaS and NbSe of all thicknesses, bulk TaSe and bulk NbS, extending over 4 orders of magnitude in and covering both clean and dirty limits. We propose that this tunability across the TMD family is controlled by the competing charge density wave (CDW) phase. Using Gor'kov's theory, we calculate how a CDW order affects the quasiparticle density of states and the resulting and . Our results suggest that CDW is the key determinant factor limiting in the TMD family. They also show that is universally enhanced by a factor of two orders of magnitude above the expected value, an effect that remains an open question.

We explore the potential of nanocrystals (a term used equivalently to nanoparticles) as building blocks for nanomaterials, and the current advances and open challenges for fundamental science developments and applications. Nanocrystal assemblies are inherently multiscale, and the generation of revolutionary material properties requires a precise understanding of the relationship between structure and function, the former being determined by classical effects and the latter often by quantum effects. With an emphasis on theory and computation, we discuss challenges that hamper current assembly strategies and to what extent nanocrystal assemblies represent thermodynamic equilibrium or kinetically trapped metastable states. We also examine dynamic effects and optimization of assembly protocols. Finally, we discuss promising material functions and examples of their realization with nanocrystal assemblies.

We explore the potential of nanocrystals (a term used equivalently to nanoparticles) as building blocks for nanomaterials, and the current advances and open challenges for fundamental science developments and applications. Nanocrystal assemblies are inherently multiscale, and the generation of revolutionary material properties requires a precise understanding of the relationship between structure and function, the former being determined by classical effects and the latter often by quantum effects. With an emphasis on theory and computation, we discuss challenges that hamper current assembly strategies and to what extent nanocrystal assemblies represent thermodynamic equilibrium or kinetically trapped metastable states. We also examine dynamic effects and optimization of assembly protocols. Finally, we discuss promising material functions and examples of their realization with nanocrystal assemblies.

MethodsToBRFV longevity in naturally-contaminated soil was tested by collecting an earth pile after a growth-cycle of ToBRFV-infected tomato plants. The soil was sampled at different time points and root-truncated tomato seedlings were planted. Virion stability at a range of pH values was determined by testing virus infectivity on Nicotiana glutinosa; by amplifying large genome segments using RT-PCR; and by transmission electron microscopy (TEM) visualization.ResultsToBRFV-infectivity in naturally-contaminated soil was profoundly reduced by day 184 of pile-age and was abolished between 205 and 385 days of pile-age. Virion stability and genome integrity were preserved over the pH range of 2-10. At pH 1, ToBRFV-infectivity and efficiency of large genome segment amplifications were reduced. At pH values above 10, modified particle morphologies were visualized by TEM, and virus infectivity was abolished …

The release of endocrine-disrupting compounds (EDCs) to the environment poses a health hazard to both humans and wildlife. EDCs can activate or inhibit endogenous endocrine functions by binding hormone receptors, leading to potentially adverse effects. Conventional analytical methods can detect EDCs at a high sensitivity and precision, but are blind to the biological activity of the detected compounds. To overcome this limitation, yeast-based bioassays have previously been developed as a pre-screening method, providing an effect-based overview of hormonal-disruptive activity within the sample prior to the application of analytical methods. These yeast biosensors express human endocrine-specific receptors, co-transfected with the relevant response element fused to the specific fluorescent protein reporter gene. We describe several molecular manipulations of the sensor/reporter circuit in a Saccharomyces cerevisiae bioreporter strain that have yielded an enhanced detection of estrogenic-like compounds. Improved responses were displayed both in liquid culture (96-well plate format) as well as in conjunction with sample separation using high-performance thin-layer chromatography (HPTLC). The latter approach allows for an assessment of the biological effect of individual sample components without the need for their chemical identification at the screening stage.

A unique on-chip method for the direct correlation of optical properties, with atomic-scale chemical–structural characteristics for a single quantum dot (QD), is developed and utilized in various examples. This is based on performing single QD optical characterization on a modified glass substrate, followed by the extraction of the relevant region of interest by focused-ion-beam–scanning electron microscope processing into a lamella for high resolution scanning transmission electron microscopy (STEM) characterization with atomic scale resolution. The direct correlation of the optical response under an electric field with STEM analysis of the same particle allows addressing several single particle phenomena: first, the direct correlation of single QD photoluminescence (PL) polarization and its response to the external field with the QD crystal lattice alignment, so far inferred indirectly; second, the identification of unique …

In earlier work, we suggested using a curved waveguide as a quantum simulator to simulate the tunnel ionization process. Here we implemented for the first time such a simulator and tested our results against the Keldysh and bending loss ionization rates. We observed also straight rays which are reminiscent of above-threshold-ionization (ATI) electrons.

The combination of a superconductor with a magnetically inhomogeneous material has been established as an efficient mechanism for the generation of long-ranged spin-polarized (spin-triplet) Cooper pairs. Evidence for this mechanism, however, has been demonstrated based on studies done on thin-film multilayers, where the strong bonds existing at the interface between the superconductor and the magnetic material should in principle enhance proximity effects and strengthen any electronic correlations. Here, we fabricate devices based on van der Waals (vdW) stacks of flakes of the Nb S 2 combined with flakes of C r 1/3 Nb S 2, which has a built-in magnetic inhomogeneity due to its helimagnetic spin texture at low temperatures. We find that the critical temperature of these vdW heterostructures is strongly dependent on the magnetic state of C r 1/3 Nb S 2, whose degree of magnetic inhomogeneity can be …

We demonstrate the design, fabrication, and experimental characterization of a single transverse mode adiabatic microring resonator (MRR) implemented using the silicon-on- insulator (SOI) platform using local oxidation of silicon (LOCOS) approach. Following its fabrication, the device was characterized experimentally and an ultrahigh intrinsic Q-factor of ∼2 million with a free spectral range (FSR) of 2 nm was achieved, giving rise to a finesse of ∼1100, the highest demonstrated so far in SOI platform at the telecom band. We have further studied our device to analyze the source of losses that occur in the MRR and to understand the limits of the achievable Q-factor. The surface roughness was quantified using AFM scans and the root mean square roughness was found to be ∼ 0.32±0.03 nm. The nonlinear losses were further examined by coupling different optical power levels into the MRR. Indeed, we could …

Biofilm formation, a major concern for healthcare systems, is initiated when bacteria adhere to surfaces. Escherichia coli adhesion is mediated by appendages, including type-1 fimbriae and curli amyloid fibers. Antifouling surfaces prevent the adhesion of bacteria to combat biofilm formation. Here, we used single-cell force-spectroscopy to study the interaction between E. coli and glass or two antifouling surfaces: the tripeptide DOPA-Phe(4F)-Phe(4F)-OMe and poly(ethylene glycol) polymer-brush. Our results indicate that both antifoulants significantly deter E. coli initial adhesion. By using two mutant strains expressing no type-1 fimbriae or curli amyloids, we studied the adhesion mechanism. Our results suggest that the bacteria adhere to different antifoulants via separate mechanisms. Finally, we show that some bacteria adhere much better than others, illustrating how the variability of bacterial cultures affects biofilm …

Emulsions are commonly used for drug delivery, yet they are usually limited to exclusively delivering either lipophilic or hydrophilic compounds. This separation negates possible synergetic therapeutic roles between such compounds. Here, we introduce a design for a short peptide that can stabilize emulsions. Upon binding certain metal ions, the peptide acts as a molecular switch, changes conformation, and becomes amphiphilic. Spectroscopic methods, NMR, and molecular dynamics provide information on the mechanism of this complexation-triggered amphiphilicity. The stability of these unique emulsions is based on histidine-metal bonds, which break at low pH values, selectively releasing their contents at the extracellular pH of tumors. Paclitaxel-encapsulated emulsion demonstrates strong activity against HeLa cells with an IC50 of 70 nM, possibly enhanced by the simultaneous release of Zn2+ ions …

In recent years there has been a shift of interest in the Nanophotonics community moving from using metallic/plasmonic materials to using high‐index dielectric materials for the construction of metasurfaces. Although high‐index dielectrics hold many advantages over their plasmonic counterparts, the selection of materials that exhibit high‐index properties, have low loss, and are complemetary metal‐oxide‐semiconductor (CMOS) compatible that also operate in the visible regime is extremely challenging. In this work, a high‐index dielectric material using silicon rich nitride (SRN) is proposed and experimentally demonstrated as a platform for solving this problem. While SRN has been used before for diffractive lenses and structural colors, here its applicability for Huygens‐type metasurfaces is focused upon. Specifically, a Huygens metasurface that operates in the visible range around a wavelength of 575 nm is …

Metasurfaces have recently risen to prominence in optical research, providing unique functionalities that can be used for imaging, beam forming, holography, polarimetry, and many more, while keeping device dimensions small. Despite the fact that a vast range of basic metasurface designs has already been thoroughly studied in the literature, the number of metasurface-related papers is still growing at a rapid pace, as metasurface research is now spreading to adjacent fields, including computational imaging, augmented and virtual reality, automotive, display, biosensing, nonlinear, quantum and topological optics, optical computing, and more. At the same time, the ability of metasurfaces to perform optical functions in much more compact optical systems has triggered strong and constantly growing interest from various industries that greatly benefit from the availability of miniaturized, highly functional, and efficient …

Metasurfaces have recently risen to prominence in optical research, providing unique functionalities that can be used for imaging, beam forming, holography, polarimetry, and many more, while keeping device dimensions small. Despite the fact that a vast range of basic metasurface designs has already been thoroughly studied in the literature, the number of metasurface-related papers is still growing at a rapid pace, as metasurface research is now spreading to adjacent fields, including computational imaging, augmented and virtual reality, automotive, display, biosensing, nonlinear, quantum and topological optics, optical computing, and more. At the same time, the ability of metasurfaces to perform optical functions in much more compact optical systems has triggered strong and constantly growing interest from various industries that greatly benefit from the availability of miniaturized, highly functional, and efficient …