Structural basis of transcriptional activation by the OmpR/PhoB-family response regulator PmrA.

PmrA, an OmpR/PhoB-family response regulator, triggers gene transcription responsible for polymyxin resistance in bacteria by recognizing promoters where the canonical-35 element is replaced by the pmra-box, representing the PmrA recognition sequence. Here, we report a cryo-electron microscopy (cryo-EM) structure of a bacterial PmrA-dependent transcription activation complex (TAC) containing a PmrA dimer, an RNA polymerase σ70 holoenzyme (RNAPH) and the pbgP promoter DNA. Our structure reveals that the RNAPH mainly contacts the PmrA C-terminal DNA-binding domain (DBD) via electrostatic interactions and reorients the DBD three base pairs upstream of the pmra-box, resulting in a dynamic TAC conformation. In vivo assays show that the substitution of the DNA-recognition residue eliminated its transcriptional activity, while variants with altered RNAPH-interacting residues resulted in enhanced transcriptional activity. Our findings suggest that both PmrA recognition-induced DNA distortion and PmrA promoter escape play crucial roles in its transcriptional activation.

Gold Fluorescence Nanoparticles for Enhanced SERS Detection in Biomedical Sensor Applications: Current Trends and Future Directions.

Nanotechnology has emerged as a pivotal tool in biomedical research, particularly in developing advanced sensing platforms for disease diagnosis and therapeutic monitoring. Since gold nanoparticles are biocompatible and have special optical characteristics, they are excellent choices for surface-enhanced Raman scattering (SERS) sensing devices. Integrating fluorescence characteristics further enhances their utility in real-time imaging and tracking within biological systems. The synergistic combination of SERS and fluorescence enables sensitive and selective detection of biomolecules at trace levels, providing a versatile platform for early cancer diagnosis and drug monitoring. In cancer detection, AuNPs facilitate the specific targeting of cancer biomarkers, allowing for early-stage diagnosis and personalized treatment strategies. The enhanced sensitivity of SERS, coupled with the tunable fluorescence properties of AuNPs, offers a powerful tool for the identification of cancer cells and their microenvironment. This dual-mode detection not only improves diagnostic accuracy but also enables the monitoring of treatment response and disease progression. In drug detection, integrating AuNPs with SERS provides a robust platform for identifying and quantifying pharmaceutical compounds. The unique spectral fingerprints obtained through SERS enable the discrimination of drug molecules even in complex biological matrices. Furthermore, the fluorescence property of AuNPs makes it easier to track medication distribution in real-time, maximizing therapeutic effectiveness and reducing adverse effects. Furthermore, the review explores the role of gold fluorescence nanoparticles in photodynamic therapy (PDT). By using the complementary effects of targeted drug release and light-induced cytotoxicity, SERS-guided drug delivery and photodynamic therapy (PDT) can increase the effectiveness of treatment against cancer cells. In conclusion, the utilization of gold fluorescence nanoparticles in conjunction with SERS holds tremendous potential for revolutionizing cancer detection, drug analysis, and photodynamic therapy. The dual-mode capabilities of these nanomaterials provide a multifaceted approach to address the challenges in early diagnosis, treatment monitoring, and personalized medicine, thereby advancing the landscape of biomedical applications.

Bioresource Polymer Composite for Energy Generation and Storage: Developments and Trends.

The ever-growing demand of human society for clean and reliable energy sources spurred a substantial academic interest in exploring the potential of biological resources for developing energy generation and storage systems. As a result, alternative energy sources are needed in populous developing countries to compensate for energy deficits in an environmentally sustainable manner. This review aims to evaluate and summarize the recent progress in bio-based polymer composites (PCs) for energy generation and storage. The articulated review provides an overview of energy storage systems, e. g., supercapacitors and batteries, and discusses the future possibilities of various solar cells (SCs), using both past research progress and possible future developments as a basis for discussion. These studies examine systematic and sequential advances in different generations of SCs. Developing novel PCs that are efficient, stable, and cost-effective is of utmost importance. In addition, the current state of high-performance equipment for each of the technologies is evaluated in detail. We also discuss the prospects, future trends, and opportunities regarding using bioresources for energy generation and storage, as well as the development of low-cost and efficient PCs for SCs.

Silver microplasma-engineered nanoassemblies on periodic nanostructures for SERS applications.

This research aimed to enhance the performance of surface-enhanced Raman scattering (SERS) substrates through the implementation of periodic nanostructures, effectively increasing surface area and uniformity. The approach involved a two-step process: initially, magnetron sputtering was employed to minimize the Raman background signal from the polymer substrate, and subsequently, the microplasma nanoparticle coating method was utilized to augment the presence of silver nanoparticles (AgNPs) for enhancing SERS efficacy. The outcome revealed several key findings: a coefficient of variation (CV) of approximately 8% for individual substrates (3 × 3 cm2), a CV of 6% between different fabrication batches, and a sustained signal strength of 85% over a storage period exceeding two months in a moisture-proof enclosure, thus meeting commercial product standards. Moreover, the substrate demonstrated a limit of detection of 8.4 × 10-7 M (306.5 ppb) for malachite green under non-resonance Raman excitation conditions along with an impressive enhancement factor of 2.69 × 106, establishing it as a high-performance and stable SERS substrate.

Recent Advances in Bioactive Carbon Nanotubes Based on Polymer Composites for Biosensor Applications.

Recent breakthroughs in the field of carbon nanotubes (CNTs) have opened up unprecedented opportunities for the development of specialized bioactive CNT-polymers for a variety of biosensor applications. The incorporation of bioactive materials, including DNA, aptamers and antibodies, into CNTs to produce composites of bioactive CNTs has attracted considerable attention. In addition, polymers are essential for the development of biosensors as they provide biocompatible conditions and are the ideal matrix for the immobilization of proteins. The numerous applications of bioactive compounds combined with the excellent chemical and physical properties of CNTs have led to the development of bioactive CNT-polymer composites. This article provides a comprehensive overview of CNT-polymer composites and new approaches to encapsulate bioactive compounds and polymers in CNTs. Finally, biosensor applications of bioactive CNT-polymer for the detection of glucose, H2O2 and cholesterol were investigated. The surface of CNT-polymer facilitates the immobilization of bioactive molecules such as DNA, enzymes or antibodies, which in turn enables the construction of state-of-the-art, future-oriented biosensors.

Plasma-Enabled Graphene Quantum Dot Hydrogels as Smart Anticancer Drug Nanocarriers.

One of the major challenges on the way to low-cost, simple, and effective cancer treatments is the lack of smart anticancer drug delivery materials with the requisite of site-specific and microenvironment-responsive properties. This work reports the development of plasma-engineered smart drug nanocarriers (SDNCs) containing chitosan and nitrogen-doped graphene quantum dots (NGQDs) for drug delivery in a pH-responsive manner. Through a customized microplasma processing, a highly cross-linked SDNC with only 4.5% of NGQD ratio can exhibit enhanced toughness up to threefold higher than the control chitosan group, avoiding the commonly used high temperatures and toxic chemical cross-linking agents. The SDNCs demonstrate improved loading capability for doxorubicin (DOX) via π-π interactions and stable solid-state photoluminescence to monitor the DOX loading and release through the Förster resonance energy transfer (FRET) mechanism. Moreover, the DOX loaded SDNC exhibits anticancer effects against cancer cells during cytotoxicity tests at minimum concentration. Cellular uptake studies confirm that the DOX loaded SDNC can be successfully internalized into the nucleus after 12 h incubation period. This work provides new insights into the development of smart, environmental-friendly, and biocompatible nanographene hydrogels for the next-generation biomedical applications.

Spin-Enhanced Lateral Flow Immunoassay for High-Sensitivity Detection of Nonstructural Protein NS1 Serotypes of the Dengue Virus.

Dengue fever is a global mosquito-borne viral infectious disease that has, in recent years, rapidly spread to almost all regions of the world. Lack of vaccination and directed treatment makes detection at the infection's early stages extremely important for disease prevention and clinical care. In this paper, we developed a rapid and highly sensitive dengue detection tool using a novel platform of diagnosis, called spin-enhanced lateral flow immunoassay (SELFIA) with a fluorescent nanodiamond (FND) as a reporter. Taking advantage of the unique magneto-optical properties of negatively charged nitrogen-vacancy centers in the FND, the SELFIA platform utilizes alternating electromagnetic fields to modulate signals from FND's fluorescence to provide sensitive and specific results. With sandwich SELFIA, we could efficiently detect all four dengue non-structural protein (NS1) serotypes (DV1, DV2, DV3, and DV4). The lowest detection concentration of the dengue NS1 antigens varied from 0.1 to 1.3 ng/mL, which is among the lowest limits of detection to date. The FND-based SELFIA technique is up to 500 and 5000 times more sensitive than carbon black and conventional gold nanoparticles, respectively. By using different anti-NS1 antibodies, we could differentiate the NS1 antigen serotypes contained in the tested samples via three simultaneous assays. Proposed SELFIA allows for both qualitative and quantitative differentiation between different NS1 protein serotypes, which will assist in the development of a highly sensitive and specific detection platform for dengue screening that has the potential to detect the disease at its early stages, especially in high-risk and limited-resource areas.

Distributed Strain Monitoring Using Nanocomposite Paint Sensing Meshes.

Strain measurements are vital for monitoring the load-bearing capacity and safety of structures. A common approach is to affix strain gages onto structural surfaces. On the other hand, most aerospace, automotive, civil, and mechanical structures are painted and coated, often with many layers, prior to their deployment. There is an opportunity to design smart and multifunctional paints that can be directly pre-applied onto structural surfaces to serve as a sensing layer among their other layers of functional paints. Therefore, the objective of this study was to design a strain-sensitive paint that can be used for structural monitoring. Carbon nanotubes (CNT) were dispersed in paint by high-speed shear mixing, while paint thinner was employed for adjusting the formulation's viscosity and nanomaterial concentration. The study started with the design and fabrication of the CNT-based paint. Then, the nanocomposite paint's electromechanical properties and its sensitivity to applied strains were characterized. Third, the nanocomposite paint was spray-coated onto patterned substrates to form "Sensing Meshes" for distributed strain monitoring. An electrical resistance tomography (ERT) measurement strategy and algorithm were utilized for reconstructing the conductivity distribution of the Sensing Meshes, where the magnitude of conductivity (or resistivity) corresponded to the magnitude of strain, while strain directionality was determined based on the strut direction in the mesh.

Synergistically Enhancing the Therapeutic Effect on Cancer, via Asymmetric Bioinspired Materials.

The undesirable side effects of conventional chemotherapy are one of the major problems associated with cancer treatment. Recently, with the development of novel nanomaterials, tumor-targeted therapies have been invented in order to achieve more specific cancer treatment with reduced unfavorable side effects of chemotherapic agents on human cells. However, the clinical application of nanomedicines has some shortages, such as the reduced ability to cross biological barriers and undesirable side effects in normal cells. In this order, bioinspired materials are developed to minimize the related side effects due to their excellent biocompatibility and higher accumulation therapies. As bioinspired and biomimetic materials are mainly composed of a nanometric functional agent and a biologic component, they can possess both the physicochemical properties of nanomaterials and the advantages of biologic agents, such as prolonged circulation time, enhanced biocompatibility, immune modulation, and specific targeting for cancerous cells. Among the nanomaterials, asymmetric nanomaterials have gained attention as they provide a larger surface area with more active functional sites compared to symmetric nanomaterials. Additionally, the asymmetric nanomaterials are able to function as two or more distinct components due to their asymmetric structure. The mentioned properties result in unique physiochemical properties of asymmetric nanomaterials, which makes them desirable materials for anti-cancer drug delivery systems or cancer bio-imaging systems. In this review, we discuss the use of bioinspired and biomimetic materials in the treatment of cancer, with a special focus on asymmetric nanoparticle anti-cancer agents.

Recent biotechnological approaches for treatment of novel COVID-19: from bench to clinical trial.

The global spread of the novel coronavirus (SARS-CoV-2) and increasing rate of mortality among different countries has raised the global concern regarding this disease. This illness is able to infect human beings through person-to-person contact at an extremely high rate. World Health Organization proclaimed that COVID-19 disease is known as the sixth public health emergency of international concern (30 January 2020) and also as one pandemic (12 March 2020). Owing to the rapid outbreak of COVID-19 worldwide, health authorities focused on discovery of effective prevention and treatment techniques for this novel virus. To date, an effective drug for reliable treatment of COVID-19 has not been registered or introduced to the international community. This review aims to provide recently presented techniques and protocols for efficient treatment of COVID-19 and investigate its morphology and treatment/prevention approaches, among which usage of antiviral drugs, anti-malarial drugs, corticosteroids, and traditional medicines, biotechnological drugs (e.g. combination of HCQ and azithromycin, remdesivir, interferons, novaferon, interferon-alpha-1b, thymosin, and monoclonal antibodies) can be mentioned.

Towards single electron transistor-based photon detection with microplasma-enabled graphene quantum dots.

Single-electron transistors (SETs) represent a new generation of electronic devices with high charge sensitivity, high switching speed, and low power consumption. Here a simple and controlled fabrication of graphene quantum dot (GQD)-based SETs for photon detectors has been demonstrated. The plasma-synthesized GQDs exhibit stable photoluminescence and are successfully used as the Coulomb islands between heteroepitaxial spherical-gold/platinum (HS-Au/Pt) nanogap electrodes. The as-fabricated GQD-SETs enable photon detection with 410 nm excitation owing to the ability of GQDs to generate photoluminescence emission.

The Impacts of Polyisoprene Physical Interactions on Sorting of Single-Wall Carbon Nanotubes.

Conjugated polymer sorting is currently the best method to select large-diameter single-walled carbon nanotubes (SWCNTs) with tunable narrow chirality in the adaption of highly desired electronics applications. The acceleration on conjugated polymers-SWCNTs interaction with long-term stability through different molecular designs; for example, longer alkyl side-chains or conjugation moieties have been extensively developed in recent years. However, the importance of the macromolecules with abundant van der Waals (VDW) interaction in the conjugated-based block copolymer system acting during SWCNTs sorting is not clearly demonstrated. In this work, a conjugated diblock copolymer involving polyisoprene (PI) and highly dense π-interaction of poly (9,9-dioctylfluorene) (PFO) is utilized to investigate the impact of natural rubber PI physical interaction on sorting effectiveness and stability. Through the rational design of diblock copolymer, PFO with ≈1200 isoprene units can remarkably enhance SWCNTs sorting ability and selected few chiralities with a diameter of ≈0.83-1.1 nm and highly stable solution for more than 1 year. The introduction of long-chain PI system is attributed not only to form weak VDW force with SWCNTs and strengthen the wrapping of PFO around the semiconducting SWCNTs but also to act as a barrier among nanotubes to prevent reaggregation of sorted SWCNTs.

Recent Advancements in Polythiophene-Based Materials and their Biomedical, Geno Sensor and DNA Detection.

In this review, the unique properties of intrinsically conducting polymer (ICP) in biomedical engineering fields are summarized. Polythiophene and its valuable derivatives are known as potent materials that can broadly be applied in biosensors, DNA, and gene delivery applications. Moreover, this material plays a basic role in curing and promoting anti-HIV drugs. Some of the thiophene's derivatives were chosen for different experiments and investigations to study their behavior and effects while binding with different materials and establishing new compounds. Many methods were considered for electrode coating and the conversion of thiophene to different monomers to improve their functions and to use them for a new generation of novel medical usages. It is believed that polythiophenes and their derivatives can be used in the future as a substitute for many old-fashioned ways of creating chemical biosensors polymeric materials and also drugs with lower side effects yet having a more effective response. It can be noted that syncing biochemistry with biomedical engineering will lead to a new generation of science, especially one that involves high-efficiency polymers. Therefore, since polythiophene can be customized with many derivatives, some of the novel combinations are covered in this review.

Current trends in chemical modifications of magnetic nanoparticles for targeted drug delivery in cancer chemotherapy.

Nowadays, magnetic nanoparticles (MNPs) have been rapidly investigated and attracted worldwide attention due to their great potential as mediators of heat for treating hyperthermia and their possibility to deliver drugs at specific locations, which can thereby limit systematic effects. Cancer therapy via MNPs proposes novel properties rather than normal methods such as almost zero side effects and a high-efficiency rate of effectiveness. The key aim of targeted drug delivery is to reduce side effects of the main cancer treatment that other usual chemotherapies will attend to the body, and thus controlling the effectiveness of the drug on a specific location that tumoral tissue exist. Herein, the high potential of MNPs has been studied, and different examples of their effectiveness on drug delivery and hypothermia therapy have been provided.

Gold nanostars-diagnosis, bioimaging and biomedical applications.

Gold Nanostars (GNS) have attracted tremendous attention toward themselves owing to their multi-branched structure and unique properties. These state of the art metallic nanoparticles possess intrinsic features like remarkable optical properties and exceptional physiochemical activities. These star-shaped gold nanoparticles can predominantly be utilized in biosensing, photothermal therapy, imaging, surface-enhanced Raman spectroscopy and target drug delivery applications due to their low toxicity and extraordinary optical features. In the current review, recent approaches in the matter of GNS in case of diagnosis, bioimaging and biomedical applications were summarized and reported. In this regard, first an overview about the structure and general properties of GNS were reported and thence detailed information regarding the diagnostic, bioimaging, photothermal therapy, and drug delivery applications of such novel nanomaterials were presented in detail. Summarized information clearly highlighting the superior capability of GNS as potential multi-functional materials for biomedical applications.

Effect of plasma polarity on the synthesis of graphene quantum dots by atmospheric-pressure microplasmas.

The aim of this study is to optimize the production of colloidal graphene quantum dots (GQD) in an aqueous solution containing sodium dodecyl sulfate (SDS) treated by an argon microplasma jet operated in open ambient air. The plasma has been investigated by optical emission spectroscopy and electrical measurements, and the produced GQDs have been studied by Raman spectroscopy, photoluminescence, UV-visible absorption, transmission electron microscopy and atomic force microscopy. We mainly focus on the influence of the polarity of the voltage applied to generate the microplasma. Although the deposited power is higher when using a positive polarity, the energy efficiency is also higher thanks to a faster synthesis rate. To understand the underlying mechanisms, we reproduced the experiments with the addition of [Formula: see text] in the aqueous solution. Results show that the GQD synthesis operates in two steps with SDS fragmentation followed by an electrolysis-related process. We demonstrate that the positive polarity performs better due to higher fragmentation rate.

Micro-patterned graphene-based sensing skins for human physiological monitoring.

Ultrathin, flexible, conformal, and skin-like electronic transducers are emerging as promising candidates for noninvasive and nonintrusive human health monitoring. In this work, a wearable sensing membrane is developed by patterning a graphene-based solution onto ultrathin medical tape, which can then be attached to the skin for monitoring human physiological parameters and physical activity. Here, the sensor is validated for monitoring finger bending/movements and for recognizing hand motion patterns, thereby demonstrating its future potential for evaluating athletic performance, physical therapy, and designing next-generation human-machine interfaces. Furthermore, this study also quantifies the sensor's ability to monitor eye blinking and radial pulse in real-time, which can find broader applications for the healthcare sector. Overall, the printed graphene-based sensing skin is highly conformable, flexible, lightweight, nonintrusive, mechanically robust, and is characterized by high strain sensitivity.

Quantifying Surface Area of Nanosheet Graphene Oxide Colloid Using a Gas-Phase Electrostatic Approach.

We demonstrate a new, facile gas-phase electrostatic approach to successfully quantify equivalent surface area of graphene oxide (GO) colloid on a number basis. Mobility diameter (dp,m)-based distribution and the corresponding equivalent surface area (SA) of GO colloids (i.e., with different lateral aspect ratios) were able to be identified by electrospray-differential mobility analysis (ES-DMA) coupled to a condensation particle counter (CPC) and an aerosol surface area analyzer (ASAA). A correlation of SA ∝ dp,m2.0 was established using the ES-DMA-CPC/ASAA, which is consistent with the observation by the 2-dimensional image analysis of size-selected GOs. An ultrafast surface area measurement of GO colloid was achieved via a direct coupling of ES with a combination of ASAA and CPC (i.e., measurement time was 2 min per sample; without size classification). The measured equivalent surface area of GO was ∼202 ± 7 m2 g-1, which is comparable to Brunauer-Emmett-Teller (BET) surface area, ∼240 ± 59 m2 g-1. The gas-phase electrostatic approach proposed in this study has the superior advantages of being fast, requiring no elaborate drying process, and requiring only a very small amount of sample (i.e., <0.01 mg). To the best of our knowledge, this is the first study of using an aerosol-based electrostatic coupling technique to obtain the equivalent surface area of graphene oxide on a number basis with a high precision of measurement.

Operando time and space-resolved liquid-phase diagnostics reveal the plasma selective synthesis of nanographenes.

Coupling atmospheric-pressure low-temperature plasmas to electrochemical reactors enables the generation of highly reactive species at plasma-liquid interfaces. This type of plasma electrochemical reactor (PEC) has been used to synthesize fluorescent nitrogen-doped graphene quantum dots (NGQDs), which are usable for multifunctional applications in a facile, simple, and sustainable way. However, the synthesis mechanism remains poorly understood, as well as the location of synthesis. To research these issues, we present an in situ diagnostics study on liquid phase chemistry during the PEC synthesis of NGQDs from chitosan. Monitoring of the photoluminescence and UV-VIS absorption at different depths in the reaction medium during plasma treatment reveals that the NGQD production initiates at the plasma-liquid interface but its completion and/or accumulation occurs at a few millimetres depth below the interface, where the liquid ceases to flow convectively, as determined by particle image velocimetry. Our study provides insights into the plasma synthesis of fluorescent GQDs/NGQDs from carbon precursors that may prove useful for achieving the scalability of PEC processes up to continuous-flow or array reactors.

Tuning Nanographene-Enhanced Raman Scattering for Rapid Label-Free Detection of Amino Acids.

The rapid and sensitive detection of amino acids is important not only for fundamental studies but also for the establishment of a healthy society. However, conventional detection methods have been hampered by the difficulties of low sensitivity, long sampling and detection times, and expensive operation and instruments. Here, we report the plasma engineering of bioresource-derived graphene quantum dots (GQDs) as surface-enhanced Raman scattering (SERS)-active materials for the rapid and sensitive detection of amino acids. Surface-functionalized GQDs with tuned structures and band gaps were synthesized from earth-abundant bioresources by using reactive microplasmas under ambient conditions. Detailed microscopy and spectroscopy studies indicate that the SERS properties of the synthesized GQDs can be tuned by controlling the band gaps of synthesized GQDs. The plasma-synthesized metal-free GQDs with surface functionalities showed improved SERS properties for rapid amino acid detection with low detection limits of 10-5 M for tyrosine and phenylalanine. Theoretical calculations suggest that charge transfer between GQDs and amino acids can enhance the SERS response of the GQDs. Our work provides insights into the controlled engineering of SERS-active nanographene-based materials using the plasma-enhanced method.