Laser Research Institute

Abstract Countering the optical network ‘capacity crunch’ calls for a radical development in optical fibres that could simultaneously minimize nonlinearity penalties, chromatic dispersion and maximize signal launch power. Hollow-core fibres (HCF) can break the nonlinear Shannon limit of solid-core fibre and fulfil all above requirements, but its optical performance need to be significantly upgraded before they can be considered for high-capacity telecommunication systems. Here, we report a new HCF with conjoined-tubes in the cladding and a negative-curvature core shape. It exhibits a minimum transmission loss of 2 dB km −1 at 1512 nm and a <16 dB km −1 bandwidth spanning across the O, E, S, C, L telecom bands (1302–1637 nm). The debut of this conjoined-tube HCF, with combined merits of ultralow loss, broad bandwidth, low bending loss, high mode quality and simple structure heralds a new opportunity to fully unleash the potential of HCF in telecommunication applications.

Ghost imaging (GI) facilitates image acquisition under low-light conditions by single-pixel measurements and thus has great potential in applications in various fields ranging from biomedical imaging to remote sensing. However, GI usually requires a large amount of single-pixel samplings in order to reconstruct a high-resolution image, imposing a practical limit for its applications. Here we propose a far-field super-resolution GI technique that incorporates the physical model for GI image formation into a deep neural network. The resulting hybrid neural network does not need to pre-train on any dataset, and allows the reconstruction of a far-field image with the resolution beyond the diffraction limit. Furthermore, the physical model imposes a constraint to the network output, making it effectively interpretable. We experimentally demonstrate the proposed GI technique by imaging a flying drone, and show that it outperforms some other widespread GI techniques in terms of both spatial resolution and sampling ratio. We believe that this study provides a new framework for GI, and paves a way for its practical applications.

The first study of photodynamic therapy in the human gastrointestinal tract using 5 aminolaevulinic acid (ALA) induced protoporphyrin IX as the photosensitising agent is described. Eighteen patients with colorectal, duodenal, and oesophageal tumours were studied. After 30-60 mg/kg of ALA given orally, biopsy specimens of tumour and adjacent normal mucosa were taken 1-72 hours later. These specimens were examined by quantitative fluorescence microscopy for assessment of sensitisation with protoporphyrin IX. Ten patients were given a second dose of ALA a few weeks later and their tumours were treated with red laser light (628 nm). With 30 mg/kg ALA, the highest fluorescence values were detected in the duodenum and oesophagus, and the lowest in the large bowel. Doubling the ALA dose in patients with colorectal tumours gave protoporphyrin IX fluorescence intensities similar to those in patients with upper gastrointestinal lesions and improved the tumour:normal mucosa protoporphyrin IX sensitisation ratio. The treated patients showed superficial mucosal necrosis in the areas exposed to laser light. Six patients had transient rises in serum aspartate aminotransferases, two mild skin photosensitivity reactions, and five mild nausea and vomiting. In conclusion, photodynamic therapy with systemically administered ALA may be a promising technique for the treatment of small tumours and areas of dysplasia such as in Barrett's oesophagus.

Computed Tomography (CT) is a powerful method for non-destructive testing (NDT) and metrology awakes with expanding application fields. To improve the spatial resolution of high energy CT, a micro-spot gamma-ray source based on bremsstrahlung from a laser wakefield accelerator was developed. A high energy CT using the source was performed, which shows that the resolution of reconstruction can reach 100 μm at 10% contrast. Our proof-of-principle demonstration indicates that laser driven micro-spot gamma-ray sources provide a prospective way to increase the spatial resolution and toward to high energy micro CT. Due to the advantage in spatial resolution, laser based high energy CT represents a large potential for many NDT applications.

Moringa peregrina plants were grown under four levels of saline water (0, 3000, 6000, 9000 ppm), and treated with sprayed Hoagland solution containing different concentrations of ZnO and Fe3O4 Nano-Particles (NP) (30, 60 and 90 mg/L); the normal Hoagland solution was used as a control. Results show that salinity levels significantly reduced growth parameters (plant height, root length, number of leaves, number of branches, shoot and root fresh and dry weights). Also, chlorophyll, carotenoids and crude protein levels decreased meanwhile proline and total carbohydrate levels, antioxidant non-enzymes (vitamins A and C) and enzymes (POD and SOD) increased. Moringa plants sprayed with Hoagland-containing ZnO and Fe3O4 NP showed an enhancement in growth parameters either under normal or saline conditions when compared to control. Also, spraying plants with Hoagland-containing ZnO and Fe3O4 NP resulted in significant reduction in Na+ and Cl- and an increase in N, P, K+, Mg2+, Mn2+, Fe, Zn; total chlorophyll, carotenoids, proline, carbohydrates, crude protein levels, antioxidant non-enzymes and enzymes when compared to control, normal Hoagland sprayed-plants. Generally, this enhancement of salt tolerance was considerable in plants sprayed with 60 mg/L ZnO and Fe3O4 NP and grown either in saline and non-saline conditions.   Key words: Moringa peregrine, nanofertilizers, salt stress, growth parameters, chemical composition.  

Self-cleaning transparent glass surfaces with periodic micro–nano structures fabricated by a femtosecond laser exhibit exceptional water repellency and thermostability.

Nonlinear propagation of intense femtosecond laser pulses in bulk transparent media leads to a specific propagation regime, termed femtosecond filamentation, which in turn produces dramatic spectral broadening, or superbroadening, termed supercontinuum generation. Femtosecond supercontinuum generation in transparent solids represents a compact, efficient and alignment-insensitive technique for generation of coherent broadband radiation at various parts of the optical spectrum, which finds numerous applications in diverse fields of modern ultrafast science. During recent years, this research field has reached a high level of maturity, both in understanding of the underlying physics and in achievement of exciting practical results. In this paper we overview the state-of-the-art femtosecond supercontinuum generation in various transparent solid-state media, ranging from wide-bandgap dielectrics to semiconductor materials and in various parts of the optical spectrum, from the ultraviolet to the mid-infrared spectral range. A particular emphasis is given to the most recent experimental developments: multioctave supercontinuum generation with pumping in the mid-infrared spectral range, spectral control, power and energy scaling of broadband radiation and the development of simple, flexible and robust pulse compression techniques, which deliver few optical cycle pulses and which could be readily implemented in a variety of modern ultrafast laser systems.

Abstract The field of next‐generation microdisplays is flourishing. Relevant display technologies, such as mini‐light emission diodes (mini‐LEDs), micro‐organic light emission diodes (micro‐OLEDs), and micro‐light emission diodes (micro‐LEDs) are thus in the urgent stage of development. From this perspective, comprehensive and systematical analyzes are conducted for the aforesaid microdisplay configurations. A holistic view of microdisplay technologies is developed with the corresponding performance metrics, providing a path for miscellaneous scenarios. Among these scenarios, the applications in augmented reality (AR), virtual reality (VR), wearable devices, and head‐up displays (HUD) are currently attracting considerable attention for deeper human‐digital interactions. However, there is a multiplicity of obstacles and challenges hindering such development. Nevertheless, recent advances in microdisplay technologies hold tremendous promise for the paradigms of these applications, taking a leap forward for next‐generation microdisplays. This review presents perspectives, relevant materials, and the technology landscape for such ongoing display technologies, offering guidance on the design of advanced microdisplays.

We have previously shown that elevated expression of mitotic kinase aurora kinase A (AURKA) in cancer cells promotes the development of metastatic phenotypes and is associated clinically with adverse prognosis. Here, we first revealed a clinically positive correlation between AURKA and autophagy-associated protein SQSTM1 in breast cancer and further demonstrated that AURKA regulated SQSTM1 through autophagy. Indeed, depletion by siRNA or chemical inhibition of AURKA by the small molecule VX-680 increased both the level of microtubule-associated protein 1 light chain 3-II (LC3-II) and the number of autophagosomes, along with decreased SQSTM1. Conversely, overexpression of AURKA inhibited autophagy, as assessed by decreased LC3-II and increased SQSTM1 either upon nutrient deprivation or normal conditions. In addition, phosphorylated forms of both RPS6KB1 and mechanistic target of rapamycin (MTOR) were elevated by overexpression of AURKA whereas they were suppressed by depletion or inhibition of AURKA. Moreover, inhibition of MTOR by PP242, an inhibitor of MTOR complex1/2, abrogated the changes in both LC3-II and SQSTM1 in AURKA-overexpressing BT-549 cells, suggesting that AURKA-suppressed autophagy might be associated with MTOR activation. Lastly, repression of autophagy by depletion of either LC3 or ATG5, sensitized breast cancer cells to VX-680-induced apoptosis. Similar findings were observed in cells treated with the autophagy inhibitors chloroquine (CQ) and bafilomycin A 1 (BAF). Our data thus revealed a novel role of AURKA as a negative regulator of autophagy, showing that AURKA inhibition induced autophagy, which may represent a novel mechanism of drug resistance in apoptosis-aimed therapy for breast cancer.

The quest to design and fabricate new antibacterial surfaces is an important task to meet the urgent demands of biomedical applications. Recently, a mechanical mechanism for killing adherent bacteria was discovered on nanopatterned surfaces, but there is a lack of understanding of the bactericidal mechanism. Here we present a quantitative thermodynamic model to study the bactericidal mechanism of nanopatterned surfaces through analyzing the total free energy change of bacterial cells. By comparing the bacterial cells on a flat surface and nanopatterned surface, our theoretical results reveal that cicada wing-like nanopatterned surfaces have more effective bactericidal properties than flat surfaces because a patterned surface leads to a drastic increase of the contact adhesion area. Our model also reveals some details of the influence mechanism, and gives some important information about how to improve the bactericidal properties through designing the morphology of the patterned surface.

Mitochondria-targeted photosensitizers with highly efficient singlet oxygen generation, bright near-infrared AIE and good two-photon absorption are obtained through ingenious molecular engineering for cancer cell-selective photodynamic therapy.

Cellular metabolisms produce reactive oxygen species (ROS) which are essential for cellular signaling pathways and physiological functions. Nevertheless, ROS act as "double-edged swords" that have an unstable redox balance between ROS production and removal. A little raise of ROS results in cell proliferation enhancement, survival, and soft immune responses, while a high level of ROS could lead to cellular damage consequently protein, nucleic acid, and lipid damages and finally cell death. ROS play an important role in various pathological circumstances. On the contrary, ROS can show selective toxicity which is used against cancer cells and pathogens. Photodynamic therapy (PDT) is based on three important components including a photosensitizer (PS), oxygen, and light. Upon excitation of the PS at a specific wavelength, the PDT process begins which leads to ROS generation. ROS produced during PDT could induce two different pathways. If PDT produces control and low ROS, it can lead to cell proliferation and differentiation. However, excess production of ROS by PDT causes cellular photo damage which is the main mechanism used in cancer treatment. This review summarizes the functions of ROS in living systems and describes role of PDT in production of controllable ROS and finally a special focus on current ROS-generating therapeutic protocols for regeneration and wound healing.

This manuscript presents superhydrophobic surfaces with extremely high Cassie–Baxter state stability <italic>via</italic> precisely tunable dual-scale and triple-scale micro–nano structures.

Terahertz waves provide a better contrast in imaging soft biomedical tissues than X-rays, and unlike X-rays, they cause no ionisation damage, making them a good option for biomedical imaging. Terahertz absorption imaging has conventionally been used for cancer diagnosis. However, the absorption properties of a cancerous sample are influenced by two opposing factors: an increase in absorption due to a higher degree of hydration and a decrease in absorption due to structural changes. It is therefore difficult to diagnose cancer from an absorption image. Phase imaging can thus be critical for diagnostics. We demonstrate imaging of the absorption and phase-shift distributions of 3.2 mm × 2.3 mm × 30-μm-thick human hepatocellular carcinoma tissue by continuous-wave terahertz digital in-line holography. The acquisition time of a few seconds for a single in-line hologram is much shorter than that of other terahertz diagnostic techniques, and future detectors will allow acquisition of meaningful holograms without sample dehydration. The resolution of the reconstructions was enhanced by sub-pixel shifting and extrapolation. Another advantage of this technique is its relaxed minimal sample size limitation. The fibrosis indicated in the phase distribution demonstrates the potential of terahertz holographic imaging to obtain a more objective, early diagnosis of cancer.

Direct cellular delivery of CRISPR/Cas9 complexes is of great significance for genome editing and other recently developed applications, such as gene expression regulation and RNA/DNA imaging. Here, we first constructed a graphene oxide (GO)-polyethylene glycol (PEG)-polyethylenimine (PEI) nanocarrier for the delivery of high-molecular-weight Cas9/single-guide RNA (sgRNA) complexes for endocytosis, endosomal escape, nuclear entry, and gene editing. The results demonstrate that the nanocarrier can be used successfully for efficient gene editing in human AGS cells with an efficiency of ∼39%. The results also show that this nanocarrier can protect sgRNA from enzymatic degradation, thus exhibiting extremely high stability, which is critical for future in vivo applications. Thus, this GO-mediated Cas9/sgRNA delivery system has potential as a new approach for biomedical research and targeted gene engineering applications.

BACKGROUND: There are different treatments for breast cancer and melanoma that mostly have some side effects. One of the therapeutic strategies is the use of natural components. Phenol components are a class of antioxidants in plants that have many biological functions like anticancer effects. Gallic acid (GA) is a natural polyhydroxy phenolic compound and commonly found in various foods. In the present study, GA effects alone and in combination with low-level laser irradiation on human dermal fibroblast cell line (HDF), human non-tumorigenic breast epithelial cell line (MCF10A), breast cancer cell line (MDA-MB-231) and melanoma cancer cell line (A375) was under the investigation. METHODS: for 90 s. Then, the cells were treated with different concentrations of GA for 24 h. In another study, the cell lines firstly were treated with GA and then exposed to low-level laser irradiation. The effects of GA and low-level laser on cell survival and apoptosis were examined using MTT assay, light microscopy, ROS production assay, fluorescence microscopy (AO/EB double staining) and flow cytometry. RESULTS: The results showed that pre-treatment with low-level laser and then GA reduced the survival of breast cancer cells and melanoma more than the first treatment with GA and then low-level laser irradiation. Our findings showed that ROS production in cells treated with both low-level laser and GA was more than the cells treated with GA alone. The apoptosis and ferroptosis assays confirmed the MTT results which combination treatment with low-level laser and then GA increase the cell death probably via apoptosis and ferroptosis cell death mechanisms compared to GA alone. CONCLUSIONS: This study suggests that low-level laser irradiation alone is not able to cause death in human normal and cancerous cells. Preirradiation followed by GA treatment did not change the cell viability in human normal significantly but reduces the cell survival of cancer cells more than GA alone.

Drug resistance to antibacterial and anticancer drugs is one of the most important global problems in the treatment field that is constantly expanding and hinders the recovery and survival of patients. Therefore, it is necessary to identify compounds that have antibacterial and anticancer properties or increase the effectiveness of existing drugs. One of these approaches is using natural compounds that have few side effects and are effective. Gallic acid (GA) has been identified as one of the most important plant polyphenols that health-promoting effects in various aspects such as bacterial and viral infections, cancer, inflammatory, neuropsychological, gastrointestinal, and metabolic disease. Various studies have shown that GA inhibits bacterial growth by altering membrane structure, and bacterial metabolism, and inhibits biofilm formation. Also, GA inhibits cancer cell growth by targeting different signaling pathways in apoptosis, increasing reactive oxygen species (ROS) production, targeting the cell cycle, and inhibiting oncogenes and matrix metalloproteinases (MMPs) expression. Due to the powerful function of GA against bacteria and cancer cells. In this review, we describe the latest findings in the field of the sources and chemical properties of GA, its pharmacological properties and bioavailability, the antibacterial and anticancer activities of GA, and its derivatives alone, in combination with other drugs and in the form of nanoformulation. This review can be a comprehensive perspective for scientists to use medicinal compounds containing GA in future research and expand its clinical applications.

A short review on LIBS industrial applications.

Abstract Photoacoustic (PA) technology can transform light energy into acoustic wave, which can be used for either imaging or therapy that depends on the power density of pulsed laser. Here, we report photosensitizer‐free polymeric nanocapsules loaded with nitric oxide (NO) donors, namely NO‐NCPs, formulated from NIR light‐absorbable amphiphilic polymers and a NO‐releasing donor, DETA NONOate. Controlled NO release and nanocapsule dissociation are achieved in acidic lysosomes of cancer cells. More importantly, upon pulsed laser irradiation, the PA cavitation can excite water to generate significant reactive oxygen species (ROS) such as superoxide radical (O 2 .− ), which further spontaneously reacts with the in situ released NO to burst highly cytotoxic peroxynitrite (ONOO − ) in cancer cells. The resultant ONOO − generation greatly promotes mitochondrial damage and DNA fragmentation to initiate programmed cancer cell death. Apart from PA imaging, PA cavitation can intrinsically amplify reactive species via photosensitization‐free materials for promising disease theranostics.

Ultrathin g-C₃N₄ nanosheets and fluorescent g-C₃N₄ quantum dots are simultaneously prepared <italic>via</italic> one-pot ethanol-thermal treatment in the presence of KOH.