Adsorption and desorption of DNA on bovine serum albumin modified gold nanoparticles

Evaluating the Effects of BSA-Coated Gold Nanorods on Cell Migration Potential and Inflammatory Mediators in Human Dermal Fibroblasts

Albumin-coated gold nanoparticles display potential biomedical applications, including cancer research, infection treatment, and wound healing; however, elucidating their interaction with normal cells remains an area with limited exploration. In this study, gold nanorods (GNR) were prepared and coated with bovine serum albumin (BSA) to produce GNR-BSA. The functionalized nanoparticles were characterized based on their optical absorption spectra, morphology, surface charge, and quantity of attached protein. The interaction between GNR-BSA and BSA with normal cells was investigated using human dermal fibroblasts. The cytotoxicity test indicated cell viability between ~63-95% for GNR-BSA over concentrations from 30.0 to 0.47 μg/mL and ~85-98% for BSA over concentrations from 4.0 to 0.0625 mg/mL. The impact of the GNR-BSA and BSA on cell migration potential and wound healing was assessed using scratch assay, and the modulation of cytokine release was explored by quantifying a panel of cytokines using Multiplex technology. The results indicated that GNR-BSA, at 10 μg/mL, delayed the cell migration and wound healing 24 h post-treatment compared to the BSA or the control group with an average wound closure percentage of 6% and 16% at 6 and 24 h post-treatment, respectively. Multiplex analysis revealed that while GNR-BSA reduced the release of the pro-inflammatory marker IL-12 from the activated fibroblasts 24 h post-treatment, they significantly reduced the release of IL-8 (p < 0.001), and CCL2 (p < 0.01), which are crucial for the inflammation response, cell adhesion, proliferation, migration, and angiogenesis. Although GNR-BSA exhibited relatively high cell viability towards human dermal fibroblasts and promising therapeutic applications, toxicity aspects related to cell motility and migration must be considered.

Visual diagnosis of COVID-19 disease based on serum metabolites using a paper-based electronic tongue

This study aims to use a paper-based sensor array for point-of-care detection of COVID-19 diseases. Various chemical compounds such as nanoparticles, organic dyes and metal ion complexes were employed as sensing elements in the array fabrication, capturing the metabolites of human serum samples. The viral infection caused the type and concentration of serum compositions to change, resulting in different color responses for the infected and control samples. For this purpose, 118 serum samples of COVID-19 patients and non-COVID controls both men and women with the age range of 14–88 years were collected. The serum samples were initially subjected to the sensor, followed by monitoring the variation in the color of sensing elements for 5 min using a scanner. By taking into consideration the statistical information, this method was capable of discriminating COVID-19 patients and control samples with 83.0% accuracy. The variation of age did not influence the colorimetric patterns. The desirable correlation was observed between the sensor responses and viral load values calculated by the PCR test, proposing a rapid and facile way to estimate the disease severity. Compared to other rapid detection methods, the developed assay is cost-effective and user-friendly, allowing for screening COVID-19 diseases reliably.

Detection of aldehydes by gold nanoparticle colorimetric array based on Tollens' reagent

Aldehydes are very common pollutants and many are possible human carcinogens. Herein, we report an easy-to-operate and low-cost method for discrimination of diverse aldehydes. Our colorimetric sensor array based on Tollens' reagent allows discrimination of ten kinds of aldehydes, showing a distinct color change from wine-red to deep yellow. In the presence of aldehydes, Ag shells are coated onto gold nanoparticles (GNPs) functionalized with diverse ligands (including bovine serum albumin, polyvinylpyrrolidone and L-cysteine), forming Au@Ag core-shell nanoparticles. The sensor array has great capacity for differentiating between ten kinds of aldehydes by color change, with accuracy and specificity of over 88%. Under optimal conditions, there is good linear correlation between Euclidean distance and formaldehyde concentrations ranging from 0.1 to 10 000 μM (R² = 0.9908). The sensor was successfully used to determine formaldehyde content in shrimp, with recovery of 85.8% to 114.82%. Our GNPs sensor shows good potential for fast, reliable identification of aldehydes in food.

Electrochemical aptasensor for 17β-estradiol using disposable laser scribed graphene electrodes

17β-Estradiol (E2), the strongest of the three major physiological estrogens in females, is an important factor in the female reproductive system. The abnormal level of E2 causes health issues, such as weak bones, urinary tract infections and even depression. Here, we present a novel, sensitive and selective, electrochemical aptasensor for detection of 17β-estradiol (E2). The E2 recognition aptamer was split into two fragments: the first fragment, functionalised with adamantane, is attached to poly(β-cyclodextrin) (poly(β-CD))-modified electrode surface through host-guest interactions between the adamantane and poly(β-CD). The second fragment, labelled with gold nanoparticles, forms the stem-loop structure with the first fragment only in the presence of E2. That specific recognition process triggers the change in the electrochemical signal (a change in the peak current from reduction of AuNPs), recorded by means of differential pulse voltammetry (DPV). The feasibility of the sensing design was firstly investigated on the commercially available glass carbon electrodes (GCE), with achieved a linear detection range of 1.0 × 10-13 to 1.0 × 10-8 M and a limit of detection (LoD) 0.7 fM. The sensing methodology was then translated onto single-use, disposable, laser-scribed graphene electrodes (LSGE) on a plastic substrate. The dynamic sensing range of E2 on LSGE was found to be 1.0 × 10-13 to 1.0 × 10-9 M, with a LoD of 63.1 fM, comparable to these of GCE. The successful translation of the developed E2 aptasensor from GCE to low-cost, disposable LSGE highlights a potential of this sensing platform in commercial, portable sensing detection systems for E2 and similar targets of biological interest.

Attaching DNA to Gold Nanoparticles With a Protein Corona

DNA-functionalized gold nanoparticles (AuNPs) have been widely used in directed assembly of materials, biosensors, and drug delivery. This conjugate may encounter proteins in these applications and proteins may affect not only DNA adsorption but also the function of the attached DNA. Bovine serum albumin (BSA) with many cysteine residues can strongly adsorb on AuNPs and this conjugate showed high colloidal stability against salt, acid and base. Similar protection effects were also observed with a few other common proteins including catalase, hemoglobin, glucose oxidase, and horseradish peroxidase. DNA oligonucleotides without a thiol label can hardly displace adsorbed BSA, and BSA cannot displace pre-adsorbed DNA either, indicating a strongly kinetically controlled system. Thiolated DNA can be attached at a low density on the AuNPs with a BSA corona. The BSA corona did not facilitate the hybridization of the conjugated DNA, while a smaller peptide, glutathione allowed faster hybridization. Overall, proteins increase the colloidal stability of AuNPs, and they do not perturb the gold-thiol bond in the DNA conjugate, although a large protein corona may inhibit the hybridization function of DNA.

Multi-responsive albumin-lonidamine conjugated hybridized gold nanoparticle as a combined photothermal-chemotherapy for synergistic tumor ablation

Herein, we developed a multifunctional nanoplatform based on the nanoassembly of gold nanoparticles (GNP) conjugated with lonidamine (LND) and aptamer AS1411 (AS-LAGN) as an effective cancer treatment. Conjugating AS1411 aptamer on the surface of the nanoparticle significantly improved particle accumulation in cancer cells via specific affinity toward the nucleolin receptors. In vitro study clearly revealed that laser irradiation-based hyperthermia effect enhanced the chemotherapeutic effects of LND. Combinational treatment modalities revealed significant apoptosis with higher cell killing effect due to increased ROS production and inhibition of cell migration. GNP's ability to convert the excited state photon energy into thermal heat enabled synergistic photothermal/chemotherapy with improved therapeutic efficacy in animal models. Moreover, immunohistochemistry staining assays confirmed the ability of AS-LAGN to induce cellular apoptosis/necrosis and ablation in tumor tissues, without causing evident damages to the surrounding healthy tissues. Altogether, this AS-LAGN nanoplatform could be a promising strategy for mitochondria-based cancer treatment. STATEMENT OF SIGNIFICANCE: We have designed a facile biodegradable multifunctional nanocarrier system to target the mitochondria, the major "power house" of the cancer cells. We have constructed a multifunctional nanoassembly of protein coronated gold nanoparticles (GNP) conjugated with lonidamine (LND) and aptamer AS1411 (AS-LAGN) as an effective combination of phototherapy with chemotherapy for cancer treatment. The LND was conjugated with albumin which was in turn conjugated to GNP via redox-liable disulfide linkage to generate oxidative stress and ROS to kill cancer cells. GNP's ability to convert the excited state photon energy into thermal heat enabled synergistic photothermal/chemotherapy with improved therapeutic efficacy in animal models. Consistently, AS-LAGN showed enhanced antitumor efficacy in xenograft tumor model with remarkable tumor regression property.

Highly Stable Conjugates of Carbon Nanoparticles with DNA Aptamers

Conjugates of carbon nanoparticles and aptamers have great potential in many areas of biomedicine. In order to be implemented in practice, such conjugates should keep their properties throughout long storage period in commonly available conditions. In this work, we prepared conjugates of carbon nanoparticles (CNP) with DNA aptamers using streptavidin-biotin reaction. Obtained conjugates possess superior stability and kept their physical-chemical and functional properties during 30 days at +4 °C and -20 °C. Proposed approach to conjugation allows loading of about 100-120 pM of biotinylated aptamer per 1 mg of streptavidin-coated CNP (CNP-Str). Aptamer-functionalized CNP-Str have zeta potential of -34 mV at pH 7, mean diameter of 168-177 nm, and polydispersity index of 0.080-0.140. High reproducibility of functionalization was confirmed by preparation of several batches of CNP-aptamer with the same size distribution and aptamer loading using independently synthesized parent CNP-Str nanoparticles. Stability of CNP-aptamer conjugates was significantly enhanced by postsynthesis addition of EDTA that prevents nuclease degradation of immobilized aptamers. Obtained nanoparticles were stable at pH ranging from 6 to 10. Optical properties of CNP-aptamer nanoparticles were also studied and their ability to quench fluorescence via Förster resonance energy transfer was shown. Taking into account properties of CNP-aptamer conjugates, we suppose they may be used in both homo- and heterogeneous colorimetric, fluorescent, and aggregation-based assays.

Neuroprotective effect of gold nanoparticles composites in Parkinson's disease model

Parkinson's disease (PD) is second most common neurodegenerative disorder worldwide. Although drugs and surgery can relieve the symptoms of PD, these therapies are incapable of fundamentally treating the disease. For PD patients, over-expression of α-synuclein (SNCA) leads to the death of dopaminergic neurons. This process can be prevented by suppressing SNCA over-expression through RNA interference. Here, we successfully synthesized gold nanoparticles (GNP) composites (CTS@GNP-pDNA-NGF) via the combination of electrostatic adsorption and photochemical immobilization, which could load plasmid DNA (pDNA) and target specific cell types. GNP was transfected into cells via endocytosis to inhibiting the apoptosis of PC12 cells and dopaminergic neurons. Simultaneously, GNP composites are also used in PD models in vivo, and it can successfully cross the blood-brain barrier by contents of GNP in the mice brain. In general, all the works demonstrated that GNP composites have good therapeutic effects for PD models in vitro and in vivo.

Decorating a single giant DNA with gold nanoparticles

We decorated a single giant DNA (1.66 × 10⁵ base pairs) with gold nanoparticles through the simple procedure of mild warming, without denaturation of the DNA molecule. Single-molecule observation with fluorescence microscopy revealed that individual decorated DNA molecules stay in the bulk solution by avoiding aggregation and precipitation, and exhibit translational and conformational fluctuation, i.e., Brownian motion. An analysis of the intra-chain fluctuation of single DNA molecules revealed that the apparent spring constant and damping coefficient of a DNA chain increased by ca. 13- and 5-fold, respectively, upon decoration with gold nanoparticles. Observation by transmission electron microscopy revealed that gold nanoparticles were stably attached to the DNA skeleton. UV-visible measurements revealed the absence of any detectable change in surface plasmon resonance, suggesting that the gold nanoparticles assemble without the formation of a densely packed aggregate. CD measurements showed that the secondary structure of decorated DNA is still essentially the B-form.

We decorated a single giant DNA (1.66 × 10⁵ base pairs) with gold nanoparticles through the simple procedure of mild warming, without denaturation of the DNA molecule.

One-step fabrication of LSPR-tuneable reconfigurable assemblies of gold nanoparticles decorated with biotin-binding proteins

Assemblies of gold nanoparticles with chain-like morphologies and new near-infrared (NIR) localized surface plasmon resonance (LSPR) are obtained by adding the biotin-binding proteins avidin, neutravidin or streptavidin to citrate-capped nanoparticles. The key idea behind this one-step fabrication method is to destabilize the colloids by adding positively charged proteins and/or by making their zeta potential less negative. The extent of assembly, and therefore the NIR LSPR, can be fine-tuned by varying the concentration of proteins as well as by changing the pH of the solution. The resulting nanoparticle clusters can also reconfigure into smaller assemblies that absorb less NIR light by adding thiolated molecules or by increasing the pH of the solution. This, along with the observation that the proteins retain their biotin-binding properties in the assemblies, makes the proposed method promising for the development of new biosensors and drug delivery platforms capable of self-regulating their optical properties as a function of chemical signals in their environment.

Creation of a bovine herpes virus 1 (BoHV-1) quantitative particle standard by transmission electron microscopy and comparison with established standards for use in real-time PCR

Standards are pivotal for pathogen quantification by real-time PCR (qPCR); however, the creation of a complete and universally applicable virus particle standard is challenging. In the present study a procedure based on purification of bovine herpes virus type 1 (BoHV-1) and subsequent quantification by transmission electron microscopy (TEM) is described. Accompanying quantitative quality controls of the TEM preparation procedure using qPCR yielded recovery rates of more than 95% of the BoHV-1 virus particles on the grid used for virus counting, which was attributed to pre-treatment of the grid with 5% bovine albumin. To compare the value of the new virus particle standard for use in qPCR, virus counter based quantification and established pure DNA standards represented by a plasmid and an oligonucleotide were included. It could be shown that the numbers of virus particles, plasmid and oligonucleotide equivalents were within one log10 range determined on the basis of standard curves indicating that different approaches provide comparable quantitative values. However, only virus particles represent a complete, universally applicable quantitative virus standard that meets the high requirements of an RNA and DNA virus gold standard. In contrast, standards based on pure DNA have to be considered as sub-standard due to limited applications.