Nanoparticle Labels Research Articles

A Review of Labeling Approaches Used in Small Extracellular Vesicles Tracing and Imaging.

Small extracellular vesicles (sEVs), a subset of extracellular vesicles (EVs) originating from the endosomal compartment, are a kind of lipid bilayer vesicles released by almost all types of cells, serving as natural carriers of nucleic acids, proteins, and lipids for intercellular communication and transfer of bioactive molecules. The current findings suggest their vital role in physiological and pathological processes. Various sEVs labeling techniques have been developed for the more advanced study of the function, mode of action, bio-distribution, and related information of sEVs. In this review, we summarize the existing and emerging sEVs labeling techniques, including fluorescent labeling, radioisotope labeling, nanoparticle labeling, chemical contrast agents labeling, and label-free technique. These approaches will pave the way for an in-depth study of sEVs. We present a systematic and comprehensive review of the principles, advantages, disadvantages, and applications of these techniques, to help promote applications of these labeling approaches in future research on sEVs.

Au-X (X=Pt/Ru)-decorated magnetic nanocubes as bifunctional nanozyme labels in colorimetric, magnetically-enhanced, one-step sandwich CRP immunoassay

Scientific interest in the investigation and application of multifunctional nanomaterials in medical diagnostics has been increasing. The employment of magnetocatalytic immunoconjugates as both analyte-capturing agents and enzyme-like catalytic labels may enable rapid preconcentration and determination of relevant antigens. In this work, we synthesized and comprehensively characterized two types of noble metal-decorated magnetic nanocubes (MDMCs) which were subsequently applied in the one-step, sandwich nanozyme-linked immunosorbent assay (NLISA). Magnetic cores allow for rapid separation from complex samples of biological origin. The catalytically active shell composed of Au-decorated Pt or Ru can effectively mimic the activity of horseradish peroxididase, retaining at the same time the ability to form stable bioconstructs through self-assembly of thiolated ligands. As a result, hybrid multifunctional nanoparticles were synthesized and used to detect C-reactive protein (CRP) in serum samples. We have also paid considerable attention to the mechanistic studies of the formation of sandwich immunocomplexes with nanoparticle labels by means of immunoenzymatic methods and surface plasmon resonance. Analytical parameters of the Pt-MDMCs-labeled NLISA (detection limit LOD = 0.336 ng mL−1, recovery = 98.0%, linear response window covering two logarithmic units) turned out to be superior to the classical, one-step ELISA based on a horseradish peroxidase. In addition, our method offers further possibility of sensitivity adjustment by changing the parameters of magnetic preconcentration, together with good long-term stability of MDMCs conjugates and their good resistance to common interferences. We believe that the proposed simple synthetic protocol will guide a new approach to applying metal-decorated magnetic nanozymes as versatile and multifunctional labels for application in subsequent pre-analytical analyte concentration and immunoassays towards clinical applications.

Treatment of vertebrobasilar artery ectasia based on MR high resolution vascular wall imaging: an ultra small Fe3O4 nanoparticle labeling method

Treatment of vertebrobasilar artery ectasia based on MR high resolution vascular wall imaging: an ultra small Fe3O4 nanoparticle labeling method

Study on the detection of anthrax by ICP-MS based on gold nanoparticle labeling.

In recent years, inductively coupled plasma mass spectrometry (ICP-MS) has been widely used in the field of molecular biology because of its unique advantages. Anthrax is a widespread and long-standing infectious disease, which affects and restricts people's work and life seriously. The study goal is to develop a new method for the detection of anthrax. A rapid, sensitive and accurate method for the detection of anthrax characteristic DNA was proposed by combing gold nanoparticles (AuNPs) and inductively coupled plasma mass spectrometry. The linear range of this method is 100-2500 pmol/L and the limit of detection of 16.61 pmol/L. The proposed method has numerous advantages, including simplicity of operation, high sensitivity, and specificity, which provides a new idea for the detection of anthrax. Importantly, this methodology has good potential for the detection of other biological substances such as bacteria and viruses by changing the modification sequence on the nanoparticle probe.

Rapid nanocatalytic reaction using antibody-conjugated gold nanoparticles for simple and sensitive detection of parathyroid hormone

Biomolecule-conjugated metal nanoparticles (NPs) have been primarily used as colorimetric labels in affinity-based bioassays for point-of-care testing. A facile electrochemical detection scheme using a rapid nanocatalytic reaction of a metal NP label is required to achieve more quantitative and sensitive point-of-care testing. Moreover, all the involved components should be stable in their dried form and solution. This study developed a stable component set that allows for rapid and simple nanocatalytic reactions combined with electrochemical detection and applied it for the sensitive detection of parathyroid hormone (PTH). The component set consists of an indium–tin oxide (ITO) electrode, ferrocenemethanol (FcMeOH), antibody-conjugated Au NPs, and ammonia borane (AB). Despite being a strong reducing agent, AB is selected because it is stable in its dried form and solution. The slow direct reaction between FcMeOH+ and AB provides a low electrochemical background, and the rapid nanocatalytic reaction allows for a high electrochemical signal. Under optimal conditions, PTH could be quantified in a wide range of concentrations in artificial serum, with a detection limit of ∼0.5 pg/mL. Clinical validation of the developed PTH immunosensor using real serum samples indicates that this novel electrochemical detection scheme is promising for quantitative and sensitive immunoassays for point-of-care testing.

Ultrasound-assisted carbon nanoparticle labeling of neoadjuvant chemotherapy for breast-conserving surgery in breast cancer.

Neoadjuvant chemotherapy has gradually become an important means of breast cancer treatment; however, tumor regression following chemotherapy remains a concern. This study was conducted to investigate the effect of ultrasound-assisted carbon nanoparticle labeling in neoadjuvant chemotherapy for breast-conserving surgery in breast cancer. This was a prospective clinical trial study (clinical registration number: ChiCTR-OOC-15006844). Sixty-eight breast cancer patients confirmed by biopsy between July 2015 and January 2017 were randomly selected from the clinical data. Of these, 32 patients were screened for neoadjuvant chemotherapy, forming a consecutive, random series. An ultrasound-guided carbon nanotube was used to mark the original tumor, and sentinel lymph node biopsies were performed. After 4-6 cycles of standard neoadjuvant chemotherapy, 26 patients were selected for breast-conserving surgery. The feasibility and validity of carbon nanoparticle labeling were analyzed through the negative rate of incision margin, the volume of resected tumors, the detection rate of black-stained sentinel lymph nodes, the recurrence rate of ipsilateral breast, and postoperative survival. In all, 32 patients underwent sentinel lymph node biopsy, 29 cases were detected (90.6%), the false-negative rate was 3.8% (1/26), and 0-4 sentinel lymph nodes (mean 1.8±1.1) were detected. A total of 26 patients underwent breast-conserving surgery, 5 underwent secondary excision, and 1 underwent subcutaneous adenectomy due to a positive margin. The minimum margin between the resected site and the infiltrated part was 1.0-2.1 cm (1.3±0.3 cm). The diameter of resected tumors ranged from 2.2 to 4.5 cm (3.1±0.6 cm). No recurrence or distant metastasis of ipsilateral breast tumors was observed during follow-up (the median follow-up time was 9 months). Ultrasound-assisted carbon nanoparticle labeling is effective for sentinel lymph node tracing before neoadjuvant chemotherapy and has a high detection rate for metastatic lymph nodes. During breast-conserving surgery, it can determine the extent of tumor resection to achieve precision surgical treatment.

Abstract TP241: Therapeutic Effects Of Magnet-induced Stem Cells Using Ferrimagnetic Iron Oxide Nanoparticles In Ischemic Stroke Model

Background: The efficiency of targeted delivery of stem cells via transplantation by intravenous injection is limited because of rapid clearance. Thus, more effective, newer methods are required. We hypothesized that combining the use of ferrimagnetic iron oxide nanoparticles (FION) labeling and magnetic fields could enhance the targeted delivery of stem cells after ischemic stroke. Methods: In a typical synthesis of FION nanocubes, iron(III) acetylacetonate was added to a mixture of oleic acid, 4-biphenylcarboxylic acid, and benzyl ether. Therapeutic effects of neural stem cells (NSC) using the magnetic nanoparticles in the cerebral ischemic stroke. Transient middle cerebral artery occlusion (MCAO) was induced in SD-rats. Iron oxide nanoparticle-labeled NSCs were injected into the tail vein. Magnetic resonance tracking and confirming labeled stem cells with Prussian blue staining. Polypeptides derived from receptors for advanced glycation end products and pharmaceutical composition for preventing and treating cerebrovascular disease comprise the same. Results: In the F3-VEGF NSC cell, FION uptake was shown as immunofluorescence. After overexpression of VEGF in F3 cells, it was confirmed by Western blotting. The measurements of cytotoxicity in FION's NSC showed toxicity over 80g but 40g was treated for 7 days and was not toxic. Six hours after MCAO induction, 4x10 6 NSCs were injected, and a magnet hat so that the stem cells implanted in the pathogen could move well. After one day, a behavioral test was conducted every week for up to 35 days. After MCAO induction, the group transplanted with FION-NSCs significantly improved in the behavioral test on Day 35 compared to the control group. In order to measure the distribution of FION in tissue, MRI was performed showing penetrating into the lesions of the white circles. As a result of ICP-MS, the magnet-applioed group was concentrated with FION 7 times more compared with the FION-only group. The distribution in brain tissue was observed through FION's Fluorescence images. Conclusions: Our study suggests that this use of a magnetic field may be useful for improving the efficacy of targeted migration of stem cells in stem-based cell therapy in ischemic brain injury.

Improvement of Seed-Mediated Growth of Gold Nanoparticle Labels for DNA Membrane-Based Assays.

Gold nanoparticles (AuNPs) are popular labels for colorimetric detection of various analytes, involving proteins, nucleic acids, viruses, and whole cells because of their outstanding optical properties, inertness, and modification variability. In this work, we present an improved approach for enhancement of color intensity for DNA membrane microarrays based on seed-mediated growth of AuNP labels. Biotin-labeled DNA is hybridized with capture oligonucleotide probes immobilized on the microarrays. Then biotin is revealed by a streptavidin-AuNP conjugate followed by the detection of AuNPs. Optimization of seed-mediated enlargement of AuNPs by the reduction of tetrachloroauric acid with hydroxylamine made it possible to change the coloring of specific spots on the microarrays from pink to a more contrasting black with minor background staining. Mean size of the resulting AuNPs was four times larger than before the enhancement. Adjusting the pH of HAuCl4 solution to 3.5 and use of a large excess of hydroxylamine increased the signal/background ratio by several times. The method's applicability was demonstrated for quantification of a short oligonucleotide of 19 bases and full-length TEM-type β-lactamase genes of 860 bp responsible for the development of bacterial resistance against β-lactam antibiotics. Improved protocol for AuNP enlargement may be further transferred to any other membrane-based assays of nucleic acids with both instrumental and visual colorimetric detection.

Lateral Flow Test System to Control Total Content of Muscle Tissues in Raw Meat Products.

Assessment of the composition of meat-containing products is the task in demand due to their frequent deviations from declared recipes. The paper presents the developed test system for immunochromatographic determination of total meat content. The assay is based on the simultaneous use of monoclonal antibodies, which specifically interacts with mammalian skeletal troponin I, and polyclonal antibodies, which specifically detect bird immunoglobulin Y. To integrate the detection of both types of meat by the same test strip, the antibodies are mixed in the analytical zone of the test strip and in complex with a gold nanoparticle label. The chosen ratios of the antibodies for both mixtures provide the same contribution of different types of mammalian and bird raw materials of muscle tissues to the label binding. The test system demonstrates suitability for products containing beef, pork, rabbit, lamb, chicken, and turkey meat. The minimal detectable content of meat in samples is 0.1%. The samples for the testing are diluted 100 times, thus eliminating matrix effects, and providing high reproducibility of the color intensity for extracts of different compositions. The obtained results allow the recommendation of the developed test system for rapid on-site control of meat products.

Rapid vertical flow technique for the highly sensitive detection of Brucella antibodies with Prussian blue nanoparticle labeling and nanozyme-catalyzed signal amplification.

Brucellosis is a chronic infectious disease caused by Brucella, which is characterized by inflammation of reproductive organs and fetal membranes, abortion, infertility, and local inflammatory lesions of various tissues. Due to the widespread prevalence and spread of brucellosis, it has not only caused huge losses to animal husbandry, but also brought serious impacts on human health and safety. Therefore, rapid and accurate diagnosis is of great significance for the effective control of brucellosis. Therefore, we have developed a rapid vertical flow technique (RVFT) using Prussian blue nanoparticles (PBNPs) as a marker material for the detection of brucellosis antibodies. Lipopolysaccharide (LPS) was purified and used to detect brucellosis antibodies to improve the sensitivity of this technique. To enhance the sensitivity of serum antibody detection, a single multifunctional compound buffer was created using whole blood as a biological sample while retaining the advantages of typical lateral flow immunoassays. After signal amplification, standard Brucella-positive serum (containing Brucella antibody at 4000 IU mL-1) could be detected in this system even at a dilution factor of 1 × 10-2. The detection limit was 40 IU mL-1, which is ten times that before signal amplification. This RVFT displayed good specificity and no cross-reactivity. This RVFT effectively avoided the false negative phenomenon of lateral flow immunoassays, was easy to operate, had a short reaction time, has good repeatability, and could elicit results that were visible to the naked eye for 2 ~ 3min without any equipment. Since this method is very important for controlling the prevalence of brucellosis, it holds great promise for application in primary medical units and veterinary brucellosis detection.

In vivo bioorthogonal labeling of rare-earth doped nanoparticles for improved NIR-II tumor imaging by extracellular vesicle-mediated targeting

In vivo bioorthogonal labeling of rare-earth doped nanoparticles for improved NIR-II tumor imaging by extracellular vesicle-mediated targeting

A New Platform of Iron Oxide-Based Nanoparticles Assay Using GMR Chip-Based Sensor With Microcontroller

The low-cost, simple, and fast quantitative assay of magnetic nanoparticles (MNPs) is important for the development of magnetic-based immunoassay applications. However, the bulky sensing element and instruments of the recent iron oxide-based MNPs assays are still concerns that should be resolved. This article reports the new platform of an iron oxide-based MNPs label assay using the commercial giant magnetoresistance (GMR) chip AAL024, manufactured by Nonvolatile Electronics (NVE) Corporation, complemented with a basic differential amplifier circuit and Arduino microcontroller (AM) to acquire the digital output voltage. The as-prepared Fe3O4@Ag label possessed (15 ± 2.6) nm of average size and behaved as soft ferromagnetic with 52.1 emu/g of saturation magnetization, and 0.15 kOe of coercive field. Sensor performance for magnetic field detection, as well as Fe3O4@Ag nanoparticles label assay, was evaluated. The results show the implementation of a basic differential amplifier op-amp circuit succeed to magnify the sensor’s response to the magnetic field up to 23 times with the output voltage in the order of volt. The employment of the AM as a voltage supply of the GMR chip, an analog-to-digital converter, and a voltage gauge simplifies the data acquisition without the additional measuring instrument. Meanwhile, for the purpose of the Fe3O4@Ag nanoparticles label assay, the sensor revealed promising performance due to the high signal linearity and the rapid detection which is only 30 s with acceptable signal stabilities.

Integrated DEP Assisted Detection of PCR Products With Metallic Nanoparticle Labels Through Impedance Spectroscopy.

Electrochemical impedance spectroscopy (EIS) is gaining immense popularity in the current times due to the ease of integration with microelectronics. Keeping this aspect in mind, various detection schemes have been developed to make impedance detection of nucleic acids more specific. In this context, the current work makes a strong case for specific DNA detection through EIS using nanoparticle labeling approach and also an added selectivity step through the use of dielectrophoresis (DEP), which enhances the detection sensitivity and specificity to match the detection capability of quantitative polymerase chain reaction (qPCR) in real-time context as compared to the individually amplified DNA (Liu et al., 2008). The detection limit of the proposed biochip is observed to be 3-4 PCR cycles for 582 bp bacterial DNA, where the complete procedure of detection starts in less than 10 min. The process of integrated DEP capture of labeled products coming out of PCR and their impedance-assisted detection is carried out in an in-house micro-fabricated biochip. The gold nanoparticles, which possess excellent optical, chemical, electronic, and biocompatibility properties and are capable of generating lump-like DNA structure without modifying its basic impedance signature are introduced to the amplified DNA through the nanoparticle labeled primers.

Extraction and quantification of polystyrene nanoplastics from biological samples

Accurate quantification of nanoplastics (NPs) in complex matrices remains a challenge, especially for biological samples containing high content of organic matters. Herein, a new method extracting and quantifying polystyrene (PS) NPs from biological samples was developed. The extraction included alkaline digestion, centrifugation, and cloud point extraction (CPE), and the quantification included gold nanoparticles formation and labeling on surfaces of the extracted NPs and thereafter measurement with single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). Results show that 25% tetramethylammonium hydroxide solution was an effective alkaline digestion solution for biological matrices, and CPE after centrifugation (3000 rpm, 10 min) was applicable to purify and enrich PS NPs with different sizes (100 and 500 nm) and surface functionalities (-COOH and –NH2 modifications) from the digestion solution. The efficiency of Au labeling on PS NPs surface was improved by about 70% in the presence of 100 μM cetyltrimethylammonium bromide. The performance of the quantification method was examined by extraction and measurement of PS NPs spiked in four representative organism samples including bacteria, algae, nematode, and earthworm, and was further validated by analyzing the accumulated PS NPs in exposed nematodes. Good recovery rates (65 ± 10%–122 ± 22%) were achieved for spiking levels of 5–50 μg g−1; the limit of detection was 3.7 × 107 particles g−1, corresponding to the mass concentration of about 0.02 and 2.5 μg g−1 for the 100 nm and 500 nm PS NPs, respectively. The established extraction and quantification methods are efficient and sensitive, providing a useful approach for further exploring the environmental behavior and toxicity of NPs.

Distinct neurotoxic TDP-43 fibril polymorphs are generated by heterotypic interactions with α-Synuclein

Amyloid aggregates of specific proteins constitute important pathological hallmarks in many neurodegenerative diseases, defining neuronal degeneration and disease onset. Recently, increasing numbers of patients show comorbidities and overlaps between multiple neurodegenerative diseases, presenting distinct phenotypes. Such overlaps are often accompanied by colocalizations of more than one amyloid protein, prompting the question of whether direct interactions between different amyloid proteins could generate heterotypic amyloids. To answer this question, we investigated the effect of α-synuclein (αS) on the DNA-binding protein TDP-43 aggregation inspired by their coexistence in pathologies such as Lewy body dementia and limbic predominant age-related TDP-43 encephalopathy. We previously showed αS and prion-like C-terminal domain (PrLD) of TDP-43 synergistically interact to generate toxic heterotypic aggregates. Here, we extend these studies to investigate whether αS induces structurally and functionally distinct polymorphs of PrLD aggregates. Using αS–PrLD heterotypic aggregates generated in two different stoichiometric proportions, we show αS can affect PrLD fibril forms. PrLD fibrils show distinctive residue level signatures determined by solid state NMR, dye-binding capability, proteinase K (PK) stability, and thermal stability toward SDS denaturation. Furthremore, by gold nanoparticle labeling and transmission electron microscopy, we show the presence of both αS and PrLD proteins within the same fibrils, confirming the existence of heterotypic amyloid fibrils. We also observe αS and PrLD colocalize in the cytosol of neuroblastoma cells and show that the heterotypic PrLD fibrils selectively induce synaptic dysfunction in primary neurons. These findings establish the existence of heterotypic amyloid and provide a molecular basis for the observed overlap between synucleinopathies and TDP-43 proteinopathies.

Single-Stranded DNA Recognition over Fluorescent Gold-Aryl Nanoparticles

Fluorescence labeling of gold-aryl nanoparticles, AuNPs-COOH, was achieved by the covalent derivatization with dansyl chloride (DNS-Cl) reagent (5-naphthalene-1-sulfonyl chloride) for potential ssDNA recognition. The fluorescent gold nanoparticles of AuNPs-C6H4-4-COO-dansyl (AuNPs-DNS) of spherical shape and a size of 19.3 ± 8.3 nm were synthesized in a carbonate-bicarbonate buffer (pH = 10.6) at 37 °C. The fluorescence emission at 475 nm was acquired using fluorescence spectroscopy and investigated using time-resolved photoluminescence. The conjugation of ssDNA to AuNPs-DNS using the freeze-thaw and salt-aging methods was confirmed by fluorescence emission quenching, gel electrophoresis separation, and lifetime decrease. Conjugated ssDNA to AuNPs-DNS using the freeze-thaw method was more efficient than the salt-aging method. The purity of ssDNA upon conjugation was measured with optical density, and the obtained A260/A280 ratio was in the range of 1.7–2.0. This research can be applied to other nucleotide recognition and theranostics.

High-Yield 99mTc Labeling of Gold Nanoparticles Carrying Atropine and Adrenaline.

This work focuses on the synthesis, purification, and analytical characterization of novel multifunctional Au NPs radiolabeled with 99mTc. These mixed-ligand shell Au NPs represent pharmacologically relevant samples for potential application in theragnostics. A ligand using a plain linker with a rather long chain consisting of 10 CH2 groups and a thiol moiety along with the PADA chelator has been used for both the attachment to the Au NP surface and for the 99mTc(CO)3+ complexation. We have combined this with our approach of stabilizing Au NP without any PEG or other stabilizing groups. Thus, monoligand shell Au NPs were radiolabeled by different strategies (prelabeling and postlabeling). Additionally, pharmacologically relevant Au NPs were synthesized carrying both a biofunctionalization with either atropine or adrenaline and the 99mTc radiolabel. All samples were obtained in very good yields (up to 80% of the total activity loaded onto the column) and completely/particularly purified using desalting columns. Detailed analytical characterization of the Au NPs before and after radiolabeling has proven the NPs' robustness throughout the process. Their intact functionalization, shape, and stability was confirmed by transmission electron microscopy (TEM), ultraviolet/visible (UV/vis) spectroscopy, dynamic light scattering (DLS), and infrared (IR) spectroscopy. The presented strategy represents a versatile building block system that can be adapted to a variety of bioactive molecules and may be of high relevance for theragnostic applications.

(Digital Presentation) Stochastic Impact Electrochemistry in a Lateral-Flow Sensor Architecture

During the recent SARS-CoV-2 pandemic, lateral flow assays (LFAs) have written an indescribable story of success, as they provide means for decentralized, low-cost, and easy-to-use testing. However, LFAs in their most common form support only qualitative results and their sensitivity and limit of detection is significantly limited by the colorimetric readout method. In contrast, single-impact electrochemistry offers the possibility to quantify species beyond picomolar concentrations by recording individual species collisions with a biased microelectrode. Within this work, we investigate the integration of stochastic sensing into a LFA-architecture by combining a wax-patterned microchannel with a microelectrode array in order to detect silver nanoparticles by their oxidative dissolution. Here, we demonstrate the possibility to resolve individual nanoparticle collisions in a paper-based microchannel using a simplified reference-on-chip setup. Furthermore, we simulated a lateral-flow sensor, by flushing previously dried silver nanoparticles towards the electrode array, where the particles are subsequently detected. This proof-of-principle illustrates that single-impact electrochemistry might be a promising technique to extend the capability of LFAs. Especially, the integration of functionalized nanoparticle labels could enable the rapid and on-site detection of very dilute species with exceptional sensitivity.

Detection of green-synthesized magnetite nanoparticles using spin-valve GMR-based sensor and their potential as magnetic labels

Exploration of magnetic nanoparticle labels for giant magnetoresistance (GMR) biosensing technology is crucial because their characteristics determine GMR-based sensor performance, related to their stray field and compatibility to biomolecule. We investigated the potency of the green-synthesized magnetite (Fe3O4) nanoparticle as a green-magnetic label on a spin-valve (SV) GMR sensor based on a [Ta (2 nm)/Ir20Mn80 (10 nm)/Co90Fe10 (3 nm)/Cu (2.2 nm)/(Co84Fe10B4 (10 nm)/Ta (5 nm)] structure that generated a 7.3 Oe exchange-bias field and 5.73% magnetoresistance. Fe3O4 nanoparticles were synthesized by a chemical coprecipitation method utilizing Moringa oleifera (MO) leaf extract as a natural reducing agent. The green-synthesized Fe3O4 nanoparticles exhibited a cubic inverse spinel structure as a pristine Fe3O4 characteristic. The crystallite size of green-synthesized Fe3O4 was larger than that of Fe3O4, reaching ∼ 14 nm, and formed a particle size of 29.1 nm. Its magnetic properties included soft ferromagnetic behavior with 55.5 emu/g saturation magnetization and 54 Oe coercivity; its saturation was lower than that of Fe3O4 due to the presence of the phytochemical compound of MO extract. In addition, to observe its potency as a magnetic label for biosensing, conventionally synthesized nanoparticles, surface modification using polyethylene glycol (PEG), and attachment of an α-amylase enzyme as a biomarker sample on green nanoparticle labels were also investigated. When measuring various concentration labels using the SV-GMR thin film, the green-synthesized Fe3O4 achieved a linear relationship and a better sensitivity of 0.098 mV/mg/mL than that of the conventional compound. The sensor could detect Fe3O4-labelled α-amylase enzyme as indicated by the decreasing output voltage, a consequence of altering the surface conditions of the nanoparticles. Therefore, green-synthesized nanoparticles are reliable and achieve competitive performance as magnetic labels in GMR sensors.

Self-assembly dynamics and effect on synthetic nanobio-optical properties by hybrid monocolored silica nanoparticle labeling of Escherichia coli

The deposition of silica nanoparticles on Escherichia coli bacteria was investigated. The noncovalent interaction between the silanized surfaces and polar components of the biomembrane resulted in a nanobiostructure. This hybrid architecture showed stable conformation characteristics evaluated with different microscopy techniques, such as bright field confocal microscopy and transmission electron microscopy (TEM). Nanobioarchitectures were detected within colloidal dispersions and in the absence of aqueous media. Nanobiointeractions were related to strong polar and hydrogen bridges’ noncovalent interactions. Thus, well-constituted and defined nanobiostructures were observed by bright field confocal microscopy and TEM after their preparation in optimal conditions. However, to evaluate their stability and internanobiostructure interactions, size distributions within variable periods were determined. Variable nanobioaggregate sizes were recorded according to nanoparticles and bacteria concentrations. From single nanolabeled E. coli with well dispersible properties, low bacteria concentrations were observed. In intermediate and high concentrations, different distributions of nanobiostructures were observed in different periods. It was observed that the incorporation of silica nanoparticles into E. coli increased their dispersibility; however, their modified E. Coli membranes with silanized nanosurfaces augmented their internanobiostructure interactions through time. Here, we discuss the dynamics and nanobio-optics properties of E. coli. Their nanobiostructures could not be considered to be static systems; their interactions are regarded as important factors for dispersibility, stability, and effects against additional chemical agents such as antibiotics.