Gold nanostructure-enhanced immunosensing: ultra-sensitive detection of VEGF tumor marker for early disease diagnosis.

We present an advanced electrochemical immunosensor designed to detect the vascular endothelial growth factor (VEGF) precisely. The sensor is constructed on a modified porous gold electrode through a fabrication process involving the deposition of silver and gold on an FTO substrate. Employing thermal annealing and a de-alloying process, the silver is eliminated from the electrode, producing a reproducible porous gold substrate. Utilizing a well-defined protocol, we immobilize the heavy-chain (VHH) antibody against VEGF on the gold substrate, facilitating VEGF detection through various electrochemical methods. Remarkably, this immunosensor performs well, featuring an impressive detection limit of 0.05 pg/mL and an extensive linear range from 0.1 pg/mL to 0.1 µg/mL. This emphasizes it's to measure biomarkers across a wide concentration spectrum precisely. The robust fabrication methodology in this research underscores its potential for widespread application, offering enhanced precision, reproducibility, and remarkable detection capabilities for the developed immunosensor.

Precision in cancer diagnostics: ultra-sensitive detection of MCF-7 breast cancer cells by gold nanostructure-enhanced electrochemical biosensing.

Timely identification of cancers is pivotal in optimizing treatment efficacy and reducing their widespread impact. This study introduces a novel biosensor for the sensitive electrochemical detection of cancer cells overexpressing mucin 1 (MUC1), a well-established model for breast cancer. The sensor substrate comprises gold columnar nanostructures obtained through glancing angle deposition (GLAD) of copper nanostructures, subsequently replaced by gold via a facile galvanic replacement process. Functionalizing these gold nanostructures with aptamers targeting the MUC1 glycoproteins, a prominent cancer biomarker, enables specific recognition of MCF-7 breast cancer cells. The proposed electrochemical sensing platform offers several advantages, including high selectivity, a wide linear range of detection, a low detection limit of 30 cells per mL, and long-term stability, rendering this sensor highly desirable for definitive breast cancer diagnosis.

Aptasensor for ovarian cancer biomarker detection using nanostructured gold electrodes.

The development of an electrochemical aptasensor for the detection of CA125 as an ovarian cancer biomarker using gold nanostructures (GNs) modified electrodes is reported. The GNs were deposited on the surface of fluorine-doped tin oxide electrodes using a simple electrochemical method and the effects of pH and surfactant concentration on the topography and electrochemical properties of the resulting GNs modified electrodes were investigated. The electrodes were characterized using field-emission scanning electron microscopy and X-ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy. The best electrode, in terms of the uniformity of the deposited GNs and the increase in electroactive surface area, was used for development of an aptasensor for CA125 tumor marker detection in human serum. Signal amplification was done by using aptamer-conjugated gold nanorods resulting in the detection limit of 2.6 U/ml and a linear range of 10 to 800 U/ml. The results showed that without the need for expensive antibodies, the developed aptasensor could specifically measure the clinically relevant concentrations of the tumor marker in human serum.

Lung Cancer Cell-Derived Exosome Detection Using Electrochemical Approach towards Early Cancer Screening.

Lung cancer is one of the deadliest cancers worldwide due to the inability of existing methods for early diagnosis. Tumor-derived exosomes are nano-scale vesicles released from tumor cells to the extracellular environment, and their investigation can be very useful in both biomarkers for early cancer screening and treatment assessment. This research detected the exosomes via an ultrasensitive electrochemical biosensor containing gold nano-islands (Au-NIs) structures. This way, a high surface-area-to-volume ratio of nanostructures was embellished on the FTO electrodes to increase the chance of immobilizing the CD-151 antibody. In this way, a layer of gold was first deposited on the electrode by physical vapor deposition (PVD), followed by thermal annealing to construct primary gold seeds on the surface of the electrode. Then, gold seeds were grown by electrochemical deposition through gold salt. The cell-derived exosomes were successfully immobilized on the FTO electrode through the CD-151 antibody, and cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods were used in this research. In the CV method, the change in the current passing through the working electrode is measured so that the connection of exosomes causes the current to decrease. In the EIS method, surface resistance changes were investigated so that the binding of exosomes increased the surface resistance. Various concentrations of exosomes in both cell culture and blood serum samples were measured to test the sensitivity of the biosensor, which makes our biosensor capable of detecting 20 exosomes per milliliter.

Introducing a 2V-resonator for the improvement of pulse stability in a high-gain Q-switched Yb:YAG thin-disk laser.

Pulse instability in Q-switched solid-state lasers at enough high repetition rates is a significant problem for getting high powers. This issue is more critical for Thin-Disk-Lasers (TDLs) due to the smallness of round-trip gain in the thin active media. The main idea of this work is that increasing the round-trip gain of a TDL makes it possible to diminish its pulse instability at high repetition rates. Accordingly, a novel 2V-resonator is introduced to overcome the low gain of TDLs, in which the passage of the laser beam from the active media is twice that of the standard V-resonator. The experiment and simulation results indicate that the threshold of laser instability considerably improves for the 2V-resonator relative to the traditional V-resonator. This improvement is well seen for various time windows of the Q-switching gate and different pump powers. By choosing appropriate Q-switching time and pump power, the laser was stably run at 18 kHz, a recorded repetition rate for Q-switched TDLs.

Stable, reproducible, and binder-free gold/copper core-shell nanostructures for high-sensitive non-enzymatic glucose detection.

The core-shell non-enzymatic glucose sensors are generally fabricated by chemical synthesis approaches followed by a binder-based immobilization process. Here, we have introduced a new approach to directly synthesis the core-shell of Au@Cu and its Au@CuxO oxides on an FTO electrode for non-enzymatic glucose detection. Physical vapor deposition of Au thin film followed by thermal annealing has been used to fabricate Au nanocores on the electrode. The Cu shells have been deposited selectively on the Au cores using an electrodeposition method. Additionally, Au@Cu2O and Au@CuO have been synthesized via post thermal annealing of the Au@Cu electrode. This binder-free and selective-growing approach has the merit of high electrooxidation activity owing to improving electron transfer ability and providing more active sites on the surface. Electrochemical measurements indicate the superior activity of the Au@Cu2O electrode for glucose oxidation. The high sensitivity of 1601 µAcm-2 mM-1 and a low detection limit of 0.6 µM are achieved for the superior electrode. Additionally, the sensor indicates remarkable reproducibility and supplies accurate results for glucose detection in human serums. Moreover, this synthesis approach can be used for fast, highly controllable and precise fabrication of many core-shell structures by adjusting the electrochemical deposition and thermal treatment parameters.

400 W average power Q-switched Yb:YAG thin-disk-laser.

We report on producing up to 403 W average power directly from an acousto-optically Q-switched Yb:YAG thin-disk laser (TDL). To achieve this power, it has theoretically and experimentally been shown that the laser stability border could be shifted toward higher repetition rates by engineering of the output coupler transmittance. This allows for stable operation of the laser at higher frequencies and a further increase in the power extraction from the active medium. Using an output coupler with 93% reflectivity, a maximum average power of 403 W at the repetition rate of 12.0 kHz has been recorded under the pump power of 1220 W. Furthermore, the maximum pulse energy of 57 mJ was produced at the repetition rate of 1.00 kHz and the pump power of 520 W. The characteristics of the laser at various Q-switching rates and the pump powers have been investigated. In addition, a numerical study for supporting the experimental results has been proposed here. To the best of our knowledge, the achieved average power and the pulse energy are the highest values reported to date from a Q-switched Yb:YAG TDL. The results pave the way to further power scaling of solid-state Q-switched oscillators.

Combination treatment of dendrosomal nanocurcumin and low-level laser therapy develops proliferation and migration of mouse embryonic fibroblasts and alter TGF-ß, VEGF, TNF-α and IL-6 expressions involved in wound healing process.

INTRODUCTION: Pressure ulcer (PU) is known as the third most costly disorder usually caused by prolonged pressure and stagnation in various parts of the body. Although several therapeutic approaches are employing, obstacles in appropriate healing for skin lesions still exist which necessitates new practical alternative or adjunctive treatments. Low level laser therapy (LLLT) as one of the mentioned new strategies have gained attention. Besides, curcumin is an herbal medicine extracted from turmeric with anti-inflammatory and antioxidative properties with promising beneficial therapeutic effects in wound healing. Employing dendrosomal nanoparticles, we overcome the hydrophobicity of curcumin in the present study. We hypothesized that combination treatment of DNC+LLLT (450 nm) simultaneously may promote the wound healing process. MATERIAL AND METHODS: MTT assay, PI staining followed by flowcytometry, scratch assay and intracellular ROS measurement were used to investigate the effects caused by DNC and LLLT (450 nm) alone and in combination, on proliferation, cell cycle, migration and oxidative stress mouse embryonic fibroblast cells, respectively. The levels of growth factors and pro-inflammatory cytokines were evaluated by qRT-PCR and ELISA. RESULTS: Our results indicated that combination exposure with DNC and LLLT leads to increased proliferation and migration of MEFs as well as being more efficient in significantly upregulating growth factors (TGF-ß, VEGF) and decline in inflammatory cytokines (TNF-α, IL-6). Moreover, findings of this research provide persuasive support for the notion that DNC could reduce the LLLT-induced enhancement in intracellular ROS in mouse embryonic fibroblasts. CONCLUSION: Concurrent exposure to anti-oxidant concentrations of DNC and LLLT enriched S phase entry and therefor increased proliferation as well as migration on MEFs through regulating the expression levels growth factors and shortening the inflammatory phase by modulating of cytokines. It should be noted that DNC were able to reduce the laser-induced oxidative stress, during wound healing, representing an informative accompaniment with LLLT.

Seed-mediated Electrochemically Developed Au Nanostructures with Boosted Sensing Properties: An Implication for Non-enzymatic Glucose Detection.

A new approach has been developed to improve sensing performances of electrochemically grown Au nanostructures (AuNSs) based on the pre-seeding of the electrode. The pre-seeding modification is simply carried out by vacuum thermal deposition of 5 nm thin film of Au on the substrate followed by thermal annealing at 500 °C. The electrochemical growth of AuNSs on the pre-seeded substrates leads to impressive electrochemical responses of the electrode owing to the seeding modification. The dependence of the morphology and the electrochemical properties of the AuNSs on various deposition potentials and times have been investigated. For the positive potentials, the pre-seeding leads to the growth of porous and hole-possess networks of AuNSs on the surface. For the negative potentials, AuNSs with carved stone ball shapes are produced. The superior electrode was achieved from AuNSs developed at 0.1 V for 900 s with pre-seeding modification. The sensing properties of the superior electrode toward glucose detection show a high sensitivity of 184.9 µA mM-1 cm-2, with a remarkable detection limit of 0.32 µM and a wide range of linearity. The excellent selectivity and reproducibility of the sensors propose the current approach as a large-scale production route for non-enzymatic glucose detection.

Cobalt-copper bimetallic nanostructures prepared by glancing angle deposition for non-enzymatic voltammetric determination of glucose.

A bimetallic nanostructure of Co/Cu for the non-enzymatic determination of glucose is presented. The heterostructure includes cobalt thin film on a porous array of Cu nanocolumns. Glancing angle deposition (GLAD) method was used to grow Cu nanocolumns directly on a fluorine-doped tin oxide (FTO) substrate. Then a thin film of cobalt was electrodeposited on the Cu nanostructures. Various characterization studies were performed in order to define the optimum nanostructure for the determination of glucose. The results showed remarkable boosting of the electrocatalytic activity of Co/Cu bimetallic structure compare to the responses achieved by the monometallic structures of Co or Cu. The sensor showed two linear response ranges for the determination of glucose at 0.55 V in 0.1 M NaOH, from 5 µM-1 mM and 2-9 mM. The sensitivity was 1741 (µA mM-1 cm-2) and 626 (µA mM-1 cm-2), respectively, while the detection limit for a signal-to-noise ratio of 3 was found to be 0.4 µM. The sensor exhibited excellent selectivity and was successfully applied to the determination of glucose in real human blood serum samples. Graphical Abstract Schematic representation of fabrication process of the glucose sensor of Co (Cobalt)/Cu (Copper) on Fluorine doped Tin Oxide (FTO). The current voltage plots show higher electrooxidation activity of the bimetallic nanostructure of Co/Cu/FTO relative to the bare Co/FTO.

Development of Dual Functional Nucleic Acid Delivery Nanosystem for DNA Induced Silencing of Bcl-2 Oncogene.

INTRODUCTION: Cancer treatment using functionalized vehicles in order to block involved genes has attracted a remarkable interest. In this study, we investigated the cellular uptake and cytotoxic effects of three sizes of anti Bcl-2 DNAi-conjugated gold nanoparticles by MCF-7 cells. METHODS: Three different sizes of gold nanoparticles were synthesized by citrate reduction method and after characterization, the nanoparticles were functionalized by Bcl-2 targeted DNAi. Cell internalization of the nanoparticles was analyzed by atomic absorption spectroscopy and light microscopy. The cytotoxic effects of the nanoparticles were investigated by MTT assay, flow cytometry and RT-PCR of the target gene. RESULTS: While poor cell internalization of bare gold nanoparticles was observed, the results demonstrated that cellular uptake of DNAi-conjugated gold nanoparticles is completely size-dependent, and the largest nanoparticle (~42 nm) revealed the highest internalization rate compared to other sizes (~14 and ~26 nm). Experimental findings showed that the DNAi-conjugated gold nanoparticles induced apoptotic pathway by silencing of the targeted Bcl-2 gene. In addition, supplementary theoretical studies demonstrated that the 42 nm DNAi-conjugated gold nanoparticles have great photothermal conversion efficiency for treatment under external illumination and these nanoparticles can be induced further cytotoxic effect by approximately 10°C temperature elevations. CONCLUSION: Remarkable photothermal properties of DNAi-conjugated 42 nm Au-NPs in parallel with their high cell internalization and cytotoxic effects introduce them as potential dual functional anticancer nanosystems.

Enhanced photocatalytic water splitting of a SILAR deposited α-Fe2O3 film on TiO2 nanoparticles.

We have investigated the effect of deposition of a α-Fe2O3 thin layer on a substrate of TiO2 nanoparticles for photoelectrochemical (PEC) water splitting. The TiO2 layer was coated on an FTO substrate using the paste of TiO2 nanoparticles. The α-Fe2O3 layer was deposited on the TiO2 thin film, using the method of Successive Ionic Layer Adsorption and Reaction (SILAR) with different cycles. Various characterizations including XRD, EDX and FE-SEM confirm the formation of α-Fe2O3 and TiO2 nanoparticles on the electrode. The UV-visible absorption spectrum confirms a remarkable enhancement of the absorption of the α-Fe2O3/TiO2/FTO composite relative to the bare TiO2/FTO. In addition, the photocurrents of the composite samples are remarkably higher than the bare TiO2/FTO. This is mainly due to the low band gap of α-Fe2O3, which extends the absorption spectrum of the α-Fe2O3/TiO2 composite toward the visible region. In addition, the impedance spectroscopy analysis shows that the recombination rate of the charge carriers in the α-Fe2O3/TiO2 is lower than that for the bare TiO2. The best PEC performance of the α-Fe2O3/TiO2 sample was achieved by the sample of 70 cycles of α-Fe2O3 deposition with about 7.5 times higher photocurrent relative to the bare TiO2.

Simultaneous isolation and detection of single breast cancer cells using surface-enhanced Raman spectroscopy.

Nowadays, cancer is one of the most dangerous and deadly disease all around the world. Cancer that is diagnosed at early stages is more likely to be treated successfully. Treatment of progressed cancer is very difficult, and generally surviving rates are much lower. Therefore, much research has been focused on developing non-invasive methods for detection of cancer and monitoring of its progress. Within this contribution, we present a novel strategy for selective isolation and detection of breast cancer cell lines (MCF-7 and BT-20) based on surface enhanced Raman scattering (SERS). A simplified protocol based on cell-aptamer interaction has been developed in which core-shell (Au@Fe3O4) nanoparticles (CSNs) were functionalized with a mucin 1 (MUC1) specific aptamer (Apt1) to capture cells through the interaction between Apt1 and overexpressed protein (MUC1) on the surface of the tumor cells. Meanwhile, a SERS nano-tag, synthesized by the conjugation of Apt1 to the surface of BSA coated and with 4-mercaptopyridine (4-Mpy) functionalized gold nanoparticles, was used to detect the isolated cells. As a conclusion, the proposed strategy can be extended to isolate and detect cells more precisely based on the detection of different kinds of biomarkers on the surface of cancer cells, simultaneously.

Label-free and simple detection of endotoxins using a sensitive LSPR biosensor based on silver nanocolumns.

This paper describes the construction of a silver-based LSPR biosensor for endotoxin detection. We used GLAD method to procure reproducible silver nanocolumns. In this work, the silver nanostructures were considerably stabilized by a SAM of MPA, and the limit of detection of biosensor was measured to be 340 pg/ml for endotoxin E. coli. Considering endotoxin B. abortus as the second type of endotoxin contamination in our target samples (HBs-ag produced in Institute Pasteur, Iran), we investigated selectivity of the biosensor in various experiments. We showed that this biosensor can selectively detect both types of endotoxins compared to other biological species. Overall, this study proposes that LSPR biosensing can be considered as a sensitive, simple, and label-free method for endotoxin detection in the quality control laboratories.

Influence of Perovskite Morphology on Slow and Fast Charge Transport and Hysteresis in the Perovskite Solar Cells.

We have investigated the influence of perovskite morphology on slow and fast charge transport in the perovskite solar cells. Solar cells with different perovskite cuboid sizes (50-300 nm) have been fabricated using various methylammonium iodide concentrations. Both the low-frequency capacitance and hysteresis are maximum for the cell with the largest perovskite grains (300 nm). The low-frequency capacitance is about three orders of magnitude greater than the intermediate frequency capacitance, indicating the great role of ions on the slow responses and hysteresis. The measurement of open-circuit voltage decay indicates that for the large grains of 300 nm up to 70% of Voc remains across the cell, even after passing ∼40 s. Such a long time Voc decay demonstrates the large accumulation of the ions at the perovskite interfaces with electron and hole transport layers, which conduct slow redistribution of the charges after the light is turned off.

Mechanism of adsorption of single and double stranded DNA on gold and silver nanoparticles: Investigating some important parameters in bio-sensing applications.

The mechanism of adsorption of single and double stranded DNAs on colloidal gold and silver nanoparticles has been studied by measuring the resistance of the nanoparticles, surrounded by various oligonucleotides, against salt induced aggregation. It is shown that both single and double stranded DNAs can be adsorbed on the metal nanoparticles and the adsorption strength is determined by the interaction between various bases of DNA and the nanoparticles. By changing the salt concentration, the difference between adsorption of various DNA strands on the nanoparticles can be specified. The results indicate that a key parameter in success of a sensing assay of DNA hybridization is the salt concentration which should be greater than a minimum threshold depending on the nanoparticles characteristics. We have also investigated the interaction mechanism between various DNA bases with the metal nanoparticles. For both gold and silver nanoparticles, adenine has the highest and thymine has the lowest attachment to the nanoparticles. From surface enhanced Raman spectroscopy (SERS) data of various bases in the presence of gold nanoparticles, the probable interaction points in the bases with the nanoparticles have been determined, which are mainly the nitrogen sites of these oligonucleotides.

Two-Step Physical Deposition of a Compact CuI Hole-Transport Layer and the Formation of an Interfacial Species in Perovskite Solar Cells.

A simple and practical approach is introduced for the deposition of CuI as an inexpensive inorganic hole-transport material (HTM) for the fabrication of low cost perovskite solar cells (PSCs) by gas-solid phase transformation of Cu to CuI. The method provides a uniform and well-controlled CuI layer with large grains and good compactness that prevents the direct connection between the contact electrodes. Solar cells prepared with CuI as the HTM with Au electrodes displays an exceptionally high short-circuit current density of 32 mA cm(-2) , owing to an interfacial species formed between the perovskite and the Cu resulting in a long wavelength contribution to the incident photon-to-electron conversion efficiency (IPCE), and an overall power conversion efficiency (PCE) of 7.4 %. The growth of crystalline and uniform CuI on a low roughness perovskite layer leads to remarkably high charge extraction in the cells, which originates from the high hole mobility of CuI in addition to a large number of contact points between CuI and the perovskite layer. In addition, the solvent-free method has no damaging side effect on the perovskite layer, which makes it an appropriate method for large scale applications of CuI in perovskite solar cells.

Adsorption of DNA on colloidal Ag nanoparticles: effects of nanoparticle surface charge, base content and length of DNA.

The adsorption of single and double stranded DNA on colloidal silver nanoparticles has been studied to investigate the effects of surface charge of the nanoparticles, the composition of the oligonucleotide and its length on the adsorption characteristics. The results explain that the nanoparticle surface charge is a key parameter determining the propensity of oligonucleotides to adsorb on nanoparticles. The adsorption also depends on the length and composition of oligonucleotide. The protective effects of both single and double stranded DNA against salt-induced aggregation dramatically increase as the DNA length increases. In contrast to other available reports, we observed that long oligonucleotides (single-stranded and double stranded) can well be adsorbed on the nanoparticles as the short ones leading to almost complete protection of nanoparticles against salt induced aggregation and hence are not suitable for the sensing applications. Finally, the light scattering from the Ag nanoparticles has been simulated and the results compared with the experiments. Our understanding should improve development of colorimetric assays for DNA detection based on aggregation of unmodified metallic nanoparticles.