Nematic liquid crystal environment enables directional propulsion of spherical droplets representing aqueous dispersion of bacterial microswimmers[1]. Here we explore how the dynamics of active droplets can be controlled by patterning the nematic environment with singular and nonsingular director field. We use the plasmonic metamasks technique to pattern the director the form of non-singular disclinations. We demonstrate that interactions of the active droplet with the director gradients of the environment can be used to control propagation direction, speed, and locations of traps that stop propulsion.

1. Rajabi, M., Baza, H., Turiv, T. & Lavrentovich, O. D. Directional self-locomotion of active droplets enabled by nematic environment. Nat. Phys., doi:https://doi.org/10.1038/s41567-020-01055-5 (2020).

An increasing demand for fast and efficient random-access pointing has led to more investigation on beam steering approaches. This capability is crucial for LiDAR, remote sensing and many other emerging applications.

Electro-Optical devices have advantages over mechanical approach that include a lower cost, faster steering rates, and a random-access beam pointing capability. We have designed, fabricated, Optimized, and characterized a recently proposed non-mechanical beam steering device based on the Pancharatnam-Berry phase. The architecture of our proposed device employs a linear array of phase control elements (PCEs) which are comprised of a fringe field switching electrode structure, are able to locally control the orientation of the liquid crystal director into a cycloidal pattern to deflect transmitted light. Efficiency data verifies a high beam steering efficiency for the proposed device.

A liquid crystal elastomer (LCE) combines a rubber-like elasticity with an orientational order, which makes the material sensitive to external cues such as temperature and light. Recently, Liu et al. [1] demonstrated that LCE coatings change their profile in response to an in-plane AC electric field. The response is attributed to the realignments of the molecular dipoles by the field and the ensuing volumetric expansion of the material [1,2]. We explore experimentally how the temperature, frequency and amplitude of the AC field affect the surface profile of the LCE coatings and demonstrate the existence of two resonance frequencies at which the response is maximized.

References:

[1] Danqing Liu, Nicholas B. Tito, and Dirk J. Broer, Protruding organic surfaces triggered by in-plane electric fields, Nature Communications 8, 1526 (2017).
[2] Guido L. A. Kusters, Inge P. Verheul, Nicholas B. Tito, Paul van der Schoot, and Cornelis Storm, Dynamical Landau–de Gennes theory for electrically-responsive liquid crystal networks, Phys. Rev. E 102, 042703 (2020).

The isolation and characterization of circulating tumor cells (CTCs) has great potential for non-invasive biopsy. In this study, a surface-enhanced Raman spectroscopy (SERS) method was developed using magnetic nanoparticles and a solid SERS-active substrate integrated with an external field-assisted microfluidic device to efficiently isolate CTCs from blood samples. A new SERS substrate was used, developed by physically modifying the surface with a femtosecond laser, sputtering the active SERS layer and chemically modifying the surface with anti-EpCAM antibodies. Magnetic nanoparticles (Fe2O3) were coated with SERS active metal and then modified with para-mercaptobenzoic acid (p-MBA), which acts simultaneously as a Raman reporter and a linker with anti-EpCAM antibodies. The sensitive immune recognition of tumor cells is aided by the introduction of a controlled external magnetic field into the microfluidic chip. The integration of the SERS-active platform and p-MBA labeled immuno-Ag@Fe2O3 nanostructures with the microfluidic device ensures lower demand for samples and analytes, precise operation, increases the reproducibility of spectral responses and enables miniaturization and portability of the presented approach. We used four target tumor cell lines with relatively large (human prostate metastatic adenocarcinoma cells (LNCaP)), medium (adenocarcinomic human alveolar basal epithelial cells (A549)), weak (human prostate tumor line (PC3)) and no expression of EpCAM (tumor cells) cervical cancer (HeLa)) to estimate the detection limits on the basis of constructed calibration curves blood samples from lung cancer patients were used to validate the developed method.[1]

1. M. Czaplicka, K. Niciński, A. Nowicka, T. Szymborski i A. Kamińska, Cancers, 2020, 12 (3315), 1-21.

The coupling between molecular conformation and chirality is a cornerstone in the construction of supramolecular helical structures of small molecules across various length scales. Inspired by biological systems, conformational preselection and control in artificial helical molecules, polymers, and aggregates has guided various applications in optics, photonics, and chiral sorting among others, which are frequently based on an inherent chirality amplification through processes such as templating and self-assembly. The so-called B4 nano- or microfilament phase formed by some bent-shaped molecules [1-5] is an exemplary case for such chirality amplification across length scales, best illustrated by the formation of distinct nano- or microscopic chiral morphologies controlled by molecular conformation. Introduction of one or more chiral centers in the aliphatic side chains led to the discovery of homochiral helical nanofilament, helical microfilament, and heliconical-layered nanocylinder morphologies. Herein, we demonstrate how a priori calculations of the molecular conformation affected by chiral side chains are used to design bent-shaped molecules that self-assemble into chiral nano- and microfilament as well as nanocylinder conglomerates despite the homochiral nature of the molecules. Furthermore, relocation of the chiral center leads to formation of helical as well as flat nanoribbons. Self-consistent data sets from polarized optical as well as scanning and transmission electron microscopy, thin film and solution circular dichroism spectropolarimetry, and synchrotron-based X-ray diffraction experiments support the progressive and predictable change in morphology controlled by structural changes in the chiral side chains. The formation of these morphologies is discussed in light of the diminishing effects of molecular chirality as the chain length increases or as the chiral center is moved away from the core-chain juncture. The type of phase (B1-columnar or B4) and morphology of the nano- or microfilaments generated can further be controlled by sample treatment conditions such as by the cooling rate from the isotropic melt or by the presence of an organic solvent in the ensuing colloidal dispersions. We show that these nanoscale morphologies can then organize into a wealth of two- and three-dimensional shapes and structures ranging from flower blossoms to fiber mats formed by intersecting flat nanoribbons.

References:

[1] L. Li, M. Salamonczyk, A. Jakli, T. Hegmann, Small 2016, 12, 3944.
[2] L. Li, M. Salamonczyk, S. Shadpour, C. Zhu, A. Jakli, T. Hegmann, Nat Commun 2018, 9, 714.
[3] S. Shadpour, A. Nemati, N. J. Boyd, L. Li, M. E. Prévôt, S. L. Wakerlin, J. P. Vanegas, M. Salamończyk, E. Hegmann, C. Zhu, M. R. Wilson, A. I. Jákli, T. Hegmann, Materials Horizons 2019, 6, 959.
[4] S. Shadpour, A. Nemati, J. Liu, T. Hegmann, ACS Appl Mater Interfaces 2020, 12, 13456.
[5] S. Shadpour, A. Nemati, M. Salamonczyk, M. E. Prevot, J. Liu, N. J. Boyd, M. R. Wilson, C. Zhu, E. Hegmann, A. I. Jakli, T. Hegmann, Small 2020, 16, e1905591.

A novel approach of organometallic compounds towards the construction of nanoparticles for cancer therapy to enhance cellular uptake by targeting nucleus and mitochondria was achieved. By mixing the organometallic compound with a biocompatible polymer, PEG50 in a proper ratio coordination driven self- assembly occurs, to yield micelles. Bond formation between Pt and carboxylate ligands confirmed with 1HNMR and 31PNMR studies. Drug loading capacity within micelles found to be 80%. Cytotoxicity studies were carried out with MTT experiments, cellular uptake and cell imaging experiments. Mechanism of action of the micelles was studied with apoptosis, γH2AX, Mitostatus and MitoSOX assays. Results reveal that synthesized nanoparticles show better therapeutic effects on several cancer types including ovarian cancer.

Sexually transmitted diseases (STDs) refer to infections and syndromes passed through sexual contact and caused by bacteria, viruses, and fungi. It was estimated that each year around 376 million people struggle with bacterial STDs. There are several methods that enable diagnosis of STDs, but each of them has some limitations e.g.: Gram staining is characterized by its low detection rate while microbial culture requires time-consuming incubation and specific conditions for bacterial growth. Even the most recommended tests - nucleic acid amplification tests (NAATs) are very expensive and not every laboratory can afford it. For the above-described reasons, there is still a need to establish rapid, reliable and sensitive method for STDs diagnosis.

More recently, a lot of studies have been done presenting the great potential of the application of SERS (Surface-enhanced Raman Spectroscopy) in diverse fields including medicine and biology. SERS is a kind of fingerprint technique based on the inelastic scattering of incident light by molecules adsorbed on the roughened metal surface (SERS-active substrate). The phenomenon of the SERS technique originates mainly from two main mechanisms: electromagnetic (EM) and chemical.

In this study, we present that SERS-based sensor and chemometric analysis can be performed successfully in direct as well as indirect manner for STD diagnosis. The indirect (confirmatory) approach is based on the identification of unknown pathogenic strain in clinical sample by comparison its spectral image to others spectral image of different bacteria. While the direct one guarantees ultrafast diagnosis (up to 15 min) by classifying SERS spectra of clinical sample to the correct group by means of supervised technique (SIMCA, PLS1-DA). The undoubted advantage of this approach is that it does not involve advance preparation of sample and any chemical reagents while maintaining ultrahigh sensitivity. Hence, both of these methods can compete with many currently used techniques.

This research may have a great impact in biomedical application since, the integration of SERS-based sensor with a small, portable Raman spectrometer could lead to the development of a handheld point-of-care device, which would enable the diagnosis of STD in extremely short time.

Surface-Enhanced Raman Spectroscopy (SERS) is a sensitive, non-destructive, rapid and powerful detection technique used for wide range of biological systems and chemicals analytes in low concentration and also as a diagnostic tool for environmental and biomedical analysis [1].To enhance the Raman signal the special SERS platform, usually made of silicon, glass or another brittle material, or metallic nanoparticles are required [2].

Due to extensive use of those chemical substances for plant fungicide and insecticide protection the detection and identification of pesticides on the surface of fruits and vegetables is a crucial issue. We show a new type of elastic SERS platform made of poly(ethylene terephthalate) (PET) covered with a layer of indium tin oxide (ITO). This composite is subjected to dielectric barrier discharge (DBD) that develops the active surface of the PET/ITO foil. To enhance the Raman signal, a modified composite was covered with a thin layer of silver using the physical vapor deposition (PVD) technique. The SERS platform was used for measurements popular pesticides, i.e., Thiram and Carbaryl and to quantitative analysis of those pesticides from fruits. The presented SERS platform exhibits excellent enhancement and reproducibility of the Raman signal, which enables the trace analysis of these pesticides in the range up to their maximum residues limit. [3].

REFERENCES

[1] Pilot R, Signorini R, Durante C, Bhamidipati DM, Fabris L., Biosensors (2019); 9, 57
[2] Mosier-Boss PA., Nanomaterials (2017);7,142
[3] Nowicka AB, Czaplicka M, Kowlaska AA, Szymborski T, Kamińska A., Biosensors (2019); 9,

The number of antibiotic-resistant bacterial strains has been dramatically increased over the past few decades[1]. With bacteria constantly evolving, humans are unable to discover new antibiotics fast enough to keep an upper hand in this race[2]. It is therefore vital to explore novel non-antibiotic-based antimicrobial drugs with high efficacy and different mechanisms of action to inhibit bacterial growth. This study was focused on designing a biocompatible and efficient nanocomposite drug delivery system containing Vitamin C-Copper nanoparticles (CuNPs) incorporated into alumina hydrogels. It has been demonstrated that γ-alumina hydrogels with CuNPs embedded in the hydrogel network can be readily formed by hydrolysis reactions of aluminum isopropoxide in water, followed by incorporation of CuNPs. The products obtained in both nanoparticles and composite forms were fully characterized by dynamic light scattering (DLS), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The CuNPs released from the hydrogels are expected to exhibit improved cellular penetration via endocytosis and could trigger apoptosis by generating Reactive oxygen species (ROS) in bacterial cells. The antibacterial efficacy of CuNPs was examined and found to be highly active against Staphylococcus aureus (SA), Pseudomonas aeruginosa (PA) as well as methicillin-resistant Staphylococcus aureus (MRSA) and Multi drug-resistant Pseudomonas aeruginosa (MDRPA).

References:

1. Kaushik, Neha, Nizam Uddin, Geon Bo Sim, Young June Hong, Ku Youn Baik, Chung Hyeok Kim, Su Jae Lee, Nagendra Kumar Kaushik, and Eun Ha Choi. "Responses of solid tumor cells in DMEM to reactive oxygen species generated by non-thermal plasma and chemically induced ROS systems." Scientific reports 5 (2015): 8587.
2. Usman, M. S., El Zowalaty, M. E., Shameli, K., Zainuddin, N., Salama, M., & Ibrahim, N. A. (2013). Synthesis, characterization, and antimicrobial properties of copper nanoparticles. International journal of nanomedicine, 8, 4467.