Nanoparticle Conjugates Research Articles

Design and assessment of lipase-CuO nanoparticle conjugates for enhanced antimicrobial efficacy against clinical pathogens

In the battle against clinical infections particularly the resistant pathogens, the creation of new antimicrobial drugs is essential. This study focuses on synthesis and characterization of Lipase-CuO nanoparticle conjugates in order to investigate their antibacterial efficiency. Lipase enzyme and CuO nanoparticles were synthesized biologically by specific selected fungal strains. Statistical optimization of lipase enzyme was done using a Plackett-Burman design giving two enhancement models for lipase production with increasing in productivity up to 143.43% (2800 U/ml). Copper oxide (CuO) nanoparticles were characterized using visual indication of greenish color formation, UV-vis spectrum analysis which revealed a strong peak at 300 nm. Also, CuO nanoparticles appeared as distinct, well-dispersed spherical particles with average size of 71.035 nm using TEM, while conjugate appears as large protein molecules linked to the nanoparticles. Also, using techniques like energy dispersive X-ray (EDAX) the resultant conjugates formation was confirmed as the elemental analysis approved its formation. The antimicrobial activity of Lipase-CuO nanoparticles conjugates was tested against a range of clinical pathogens. The results demonstrated a significant increase in antimicrobial potency compared to both CuO nanoparticles and lipase alone particularly against E. coli strain NRC B-3703 with remarkable increase of 373.6% and 75% followed by S. aureus with increase of 50 and 42.8%compared to that of individual CuO nanoparticles and lipase enzyme, respectively. These findings suggest that Lipase-CuO nanoparticle conjugates hold great promise as a novel antimicrobial strategy, offering a potential solution to combat bacterial infections, especially those caused by multidrug-resistant strains. The study highlights the importance of nanotechnology in enhancing the efficacy of traditional antimicrobial agents and opens new avenues for targeted antimicrobial therapies.

Chemical Conjugation of Iron Oxide Nanoparticles for the Development of Magnetically Directable Silk Particles.

Magnetically directable materials containing iron oxide nanoparticles (IONPs) have been utilized for a variety of medical applications, including localized drug delivery. Regenerated silk fibroin (RSF) has also been used in numerous regenerative medicine and drug delivery applications, given its biocompatibility and tunable properties. In this work, we explored the hypothesis that chemically conjugating IONPs to RSF to anchor the IONPs to silk microparticles would provide better magnetic guidance than nonconjugated IONPs untethered to silk microparticles. IONPs were fabricated using a coprecipitation method and conjugated with glutathione (GSH) prior to mixing with RSF. IONPs incorporated into RSF were mixed with potassium phosphate buffer to fabricate microparticles. IONPs with and without GSH were characterized for particle size, shape, morphology, GSH conjugation efficiency, and composition. Silk iron microparticles (SIMPs) were also characterized for particle size, shape, and composition and tested for stability, degradation properties, magnetic movability, and cytotoxicity. IONPs demonstrated a uniform size distribution and spherical morphology. Conjugation of IONPs with GSH was verified through changes in the X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) spectra. IONPs and RSF were able to be chemically conjugated and fabricated into SIMPs, which demonstrated a spherical and porous morphology. FTIR revealed an increased β-sheet content in SIMPs, suggesting that the IONPs may be inducing conformational changes in the silk fibroin. SIMPs showed stability up to 4 weeks in ultrapure water and rapid enzymatic degradation within 24 h. SIMPs were able to be moved magnetically through solution and through a hydrogel and were not cytotoxic.

Advancing Cancer Drug Delivery with Nanoparticles: Challenges and Prospects in Mathematical Modeling for In Vivo and In Vitro Systems.

Mathematical models are crucial for predicting the behavior of drug conjugate nanoparticles and optimizing drug delivery systems in cancer therapy. These models simulate interactions among nanoparticle properties, tumor characteristics, and physiological conditions, including drug resistance and targeting specificity. However, they often rely on assumptions that may not accurately reflect in vivo conditions. In vitro studies, while useful, may not fully capture the complexities of the in vivo environment, leading to an overestimation of nanoparticle-based therapy effectiveness. Advancements in mathematical modeling, supported by preclinical data and artificial intelligence, are vital for refining nanoparticle-based therapies and improving their translation into effective clinical treatments.

Tailoring reactive handles on the surface of nanoparticles for covalent conjugation of biomolecules

Surface modification of nanoparticles involves numerous types of active molecules such as DNA, antibodies, enzymes or carbohydrates.

EARLY DIAGNOSIS OF ALZHEIMER’S DISEASE USING A SIMPLE AND SENSITIVE NANOBIOSENSOR

Abstract Existing diagnostic methods for Alzheimer’s disease (AD), such as PET/MRI imaging and cerebrospinal fluid tests, are invasive and/or costly. Recent studies have demonstrated that exosomes (nanoscale extracellular vesicles carrying specific biomarkers that can traverse blood-brain barrier) are ideal sources of AD biomarkers, which can be conveniently collected from peripheral body fluids like blood and saliva. Detection of AD exosomal biomarkers opens a new avenue for non-invasive diagnosis of AD. However, the concentrations of AD exosomal biomarkers in body fluids are extremely low. Therefore, highly sensitive analytical techniques such as mass spectrometry are required to measure the exosomal biomarkers accurately. Unfortunately, these sensitive techniques come with high costs and can be cumbersome, limiting their widespread use in clinical settings. In this research, we report a simple and low-cost nano-biosensor for ultrasensitive detection of AD exosomal biomarkers. The nano-biosensor relies on metal nanoparticles as labels or signal transducers. After conjugation of the metal nanoparticles with bioreceptors specific to AD exosomal biomarkers, the nanoparticle-bioreceptor conjugates can specifically catalyze the formation of colorimetric signal that can be conveniently quantified by an inexpensive spectrophotometer. The nano-biosensor is expected to be able to detect AD exosomal biomarkers from blood and/or saliva samples, representing a minimally invasive and accessible technology for early diagnosis of AD.

Resolving the Kinetics of Single-Walled Carbon Nanotube-Polyester Polyurethane Nanoparticle Conjugate Fluorescence Sensors toward Polymer Degrading Enzymes.

Single-walled carbon nanotubes (SWCNTs) are fluorescent materials that have been developed as sensors for measuring the activities of enzymes. However, most sensors to date rely on end-point measurement and empirical functions to correlate enzyme concentrations with fluorescence responses. Less emphasis is put on analyzing time-dependent fluorescence responses and their connections with enzymatic kinetics. Here, improved from our previous sensor design, we use trimethylchitosan-wrapped SWCNTs to measure the enzymatic degradation rate of Impranil nanoparticles, a polyester polyurethane model substrate. Through careful analysis of the characteristic time constant and saturation fluorescence, which are resolved from time-dependent brightening responses of the sensors, linear relations are found between fluorescence change rates and both enzyme concentrations and Impranil-to-SWCNT ratios, thus showing that the reaction is first-ordered toward both enzyme and substrate concentrations. The proposed sensor design and data analysis strategy can quantitively determine the relative enzymatic activity and provide insights into the kinetics of sensors and enzymatic reactions.

Combining functionalities-nanoarchitectonics for combatting bacterial infection.

New antimicrobial and anti-inflammatory therapeutics are needed because of antibiotic resistance development and resulting complications such as inflammation, ultimately leading to septic shock. The antimicrobial effects of various nanoparticles (NPs) are currently attracting intensive research interest. Although various NPs display potent antimicrobial effects against strains resistant to conventional antibiotics, the therapeutic use of such materials is restricted by poor selectivity between bacteria and human cells, leading to adverse side effects. As a result, increasing research efforts during the last few years have focused on targeting NPs against bacteria and other components in the infection micro-environment. Examples of approaches explored include peptide-, protein- and nucleic acid-based NP coatings for bacterial membrane recognition, as well as NP conjugation with enzyme substrates or other moieties that respond to bacterial or other enzymes present in the infection micro-environment. In general, this study aims to add to the literature on the antimicrobial effects of nanomaterials by discussing surface modification strategies for targeting bacterial membranes and membrane components, as well as how such surface modifications can improve the antimicrobial effects of nanomaterials and simultaneously decrease toxicity towards human cells and tissues. In doing so, the biological effects observed are related throughout to the physico-chemical modes of action underlying such effects.

Synthesis of eco-friendly lipid-magnetite nanocomposite encapsulated Poinciana extract as promising insecticide against Culex pipiens

Mosquito-borne diseases represent a growing health challenge over time. Nanostructured lipid carriers (NLCs) are the second generation of solid lipid nanoparticles (SLNs), and they continue to attract significant interest as potential diagnostic and therapeutic tools in disease inhibition and insect control. Activated ingredients presented in the Poinciana leaves were extracted and GC–MS data indicated an increased abundance of terpenes, flavonoids, and phenolic substances. Poinciana extract was encapsulated to the vicinity of nanostructure lipid carrier, Po-NLC, and surface modified with magnetic nanoparticles, Po-NLC-MNPs. The synthesized nanoparticles depicted average particle size of 73.2 and 75.55 nm while zeta potential of (− 29.4) and (‒ 4.44 mV) for Po-NLC and Po-NLC-MNPs, respectively. Transmission electron microscope and morphology determination showed regular, irregular spherical and oval shapes with diverse single particle size. X-rays diffraction pattern of the freely synthesized MNPs was compared to the decorated NLC and the results manifested that the NLC was successfully decorated with MNPs. The larvicidal activity of plant extract, Poinciana extract (Po), and their nanoparticle conjugates against 3rd instar larvae of Culex pipiens was evaluated at 50, 100, 200, 500, 1000, and 1500 ppm concentrations. Both high and low concentrations of Po-NLC-MNPs, indicated potential larval mortality than plant extracts (Po extract) itself. The mortality rate reached 100% for 3rd instar larvae. Based on their relative toxicity, (Po-NLC-MNPs) was the best at killing larvae, followed by Po-NLC. The synthesized nps were checked for their cytotoxic effect against wi38 cell line. The in-vitro cytotoxicity results indicated that there was no significant cytotoxicity and the nanocomposite barely caused weak changes in the tested cells. The synthesized nanoparticles have potential to create a new generation of eco-friendly, effective alternatives for controlling mosquito-borne diseases.

Membrane chromatographic test system for the determination of bisphenol A in drinking water based on the use of an aptamer

A membrane test system has been developed for the rapid determination of bisphenol A in drinking water, utilizing a conjugate of gold nanoparticles with an aptamer that specifically binds the target analyte, and a conjugate of mercaptosuccinic acid with a carrier protein impregnated in the test zone of the strip. The working principle of the test system is based on the binding of free gold nanoparticles in the test zone, which are formed as a result of the competitive interaction of the aptamer with bisphenol A and its release from the surface of the gold nanoparticles. Conjugates of gold nanoparticles with aptamers of different compositions were obtained and tested. Optimal conditions were selected to achieve a low detection limit for bisphenol A. The developed test system allows for the detection of bisphenol A within 15 minutes with a detection limit of 13.5 ng/mL. The suitability of the test system was confirmed by testing drinking water; the detection rate of bisphenol A ranged from 88.2 to 101.3%.

Antibacterial and anticancer activities of three novel lectin-conjugated chitosan nanoparticles

To the best of our knowledge, this is the first attempt to synthesize, characterize, and determine the antibacterial and anticancer effects of three novel conjugates of plant lectins: phytohemagglutinin lectin (PHA), soybean agglutinin (SBA), and peanut agglutinin (PNA) with chitosan nanoparticles (CHNPs). The lectin concentration within prepared conjugates was estimated using nannodrop, and the highest concentration was 0.96 mg/ml in PHA-CHNPs. SDS-PAGE showed the molecular weights of conjugates ranged from 26.9 to 63.9 kDa. UV spectrophotometer recorded the absorbance peaks of conjugates somewhere between 200 and 230 nm. Hemagglutination analysis verified the presence of actively binding lectins. The three conjugates showed strong antibacterial activity against Gram-positive and Gram-negative bacteria compared to pure lectins and chitosan nanoparticles. The highest inhibition zone was 55.67 ± 4.04, 38.67 ± 5.51, and 37.33 ± 2.52 for PHA-CHNPs against Enterococcus faecalis, Salmonella typhimurium, and Shigella sonnei, respectively, followed by 36.3 ± 0.15 for PNA-CHNPs against Staphylococcus aureus. The lowest MIC was 1.5 µg/ml for PHA-CHNPs against Enterococcus faecalis, followed by 12 µg/ml for PNA-CHNPs and SBA-CHNPs against Salmonella typhimurium and Enterococcus faecalis, respectively. TEM microphotographs show the conjugation pattern between lectins and chitosan nanoparticles and the morphological differences between control, treated bacteria, and cancer cells. Moreover, 100 μg/ml of PHA-CHNPs affect tongue carcinoma (HNO-97), colorectal cancer (HT-29), and human melanoma (A375) cancer cell lines, reducing cell viability by 38.78 ± 1.85%, 49.88 ± 1.11%, and 66.92 ± 3.60%, respectively. This study develops three innovative conjugates of lectin chitosan nanoparticles that need to be tested as potential antibacterial and anticancer agents for medical and cancer therapy applications.Key points• Lectin-conjugated chitosan nanoparticles exhibit antibacterial activity.• All conjugates are safe for oral epithelial cells and human skin fibroblasts.• The PHA-CHNP conjugates have anticancer activity against HNO-97, HT-29, and A375.

Computational identification of PDL1 inhibitors and their cytotoxic effects with silver and gold nanoparticles

Immunotherapy is a promising treatment for cancer that aims to boost the immune system’s response to cancer cells. This can be achieved by blocking Programmed cell death protein 1/Programmed death-ligand 1 (PD1/PDL1), which activates T cells. In this work, the aim was to find high-affinity drugs against PDL1 using computational tools and conjugate nanoparticles with them. The cytotoxic activity of the nanoparticle conjugated drugs was then tested. The screening of 100,000 drugs from the ZINC database and FDA-approved drugs was done computationally. The physicochemical properties and toxicity of the drugs were analyzed using SwissADME and ProTox-II, respectively. Silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were synthesized using extracts of Catharanthus roseus flowers and Juglans regia shells, respectively. The characterization of AgNPs and AuNPs was performed using UV–Vis spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Their conjugation with the drugs Irinotecan, Imatinib, and Methotrexate was also confirmed using UV–Vis, FTIR, and Dynamic light scattering (DLS). The top screened drugs were ZINC1098661 and 3 FDA-approved drugs (Irinotecan, Imatinib, and Methotrexate). Docking studies revealed that Irinotecan had the highest binding affinity towards PDL1 when conjugated with silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs). The Irinotecan-PDL1 complex was confirmed as the most stable through molecular dynamics simulations. The result of the methylthiazol tetrazolium (MTT) assay showed that conjugated AgNPs and AuNPs with Irinotecan had a higher toxic effect on the A549 cancer cell line than AgNPs and AuNPs conjugated with Imatinib. This study provides a promising avenue for further investigation and development of nanoparticle-drug conjugates as a potential cancer immunotherapy strategy.

Comparative Characteristics of Immunochromatographic Test Systems for Tylosin Antibiotic in Meat Products.

Tylosin (TYL) is a macrolide antibiotic widely used in animal husbandry. Due to associated health risks, there is a demand for sensitive methods for mass screening of TYL in products of animal origin. This article describes the development of lateral flow immunoassays (LFIAs) for TYL detection using direct (anti-TYL antibodies conjugated with nanoparticles) and indirect antibody labeling (anti-species antibodies conjugated with nanoparticles and combined with native anti-TYL antibodies). The choice of LFIA conditions, such as concentrations of hapten-protein conjugates, specific antibodies, and gold nanoparticle (GNP) conjugates with antibodies, as well as incubation time of reagents and the concentration of detergent in the sample buffer, is presented. The achieved limits of TYL detection using LFIAs with indirect labeling were 0.8 ng/mL (visual) and 0.07 ng/mL (instrumental), compared to 4 ng/mL (visual) and 0.4 ng/mL (instrumental) for the case of direct labeling. The sensitivity of the LFIA using the indirect format was up to seven times higher, allowing the determination of the target analyte at low concentrations. TYL detection in ground meat using LFIA with indirect antibody labeling ranged from 76-119%.

Excellent properties of NaF and NaBr induced DNA/gold nanoparticle conjugation system: Better stability, shorter modified time, and higher loading capacity

The functionalization of gold nanoparticle (AuNP) is the key procedure for the biochemical and biomedical application. The conventional salt-aging method requires the stepwise additions of NaCl and excessive thiolated DNA, mainly due to the poor tolerance of the DNA/AuNP mixture toward NaCl. Herein, we found that NaF is capable of improving the stability for the modification of AuNP with different bases of DNA sequences (poly A/T/C/G), and allows for adding up with a high concentration of 200 mM at one time, which greatly reduces the total modification time to 0.5–1 h. Intriguingly, the introduction of NaBr effectively increases the DNA loading capacity. Besides the advantages of NaF and NaBr, the modification performance is improved via the introduction of the oligo A/T spacer for the G-rich DNA sequences. Furthermore, this method shows the superiority to another two methods (pH 3-based and salt-aging) in terms of the loading capacity or sequence components.

Nondestructively Assemble Cell Membrane-Coated Nanoparticles by Host-Guest Interactions for Efficient Capture of Bioactive Compounds.

Cell membrane-coated nanoparticles (CNPs) have emerged as an attractive nanomedical tool. The basic premise is that the surface properties of natural cells can be integrated with the physical and chemical properties of nanoparticles by coating them with cell membranes. However, the degree of preservation of membrane proteins on nanoparticles, a key indicator related to the biomedical function of these biomimetic systems, is largely affected by the coating process. Herein, we report a supramolecular cell membrane conjugation strategy mediated by host-guest interactions to assemble CNPs without compromising protein activities. β-cyclodextrin (β-CD) was rapidly and stably inserted into the cell membrane by a lipid anchor without affecting the function of membrane proteins, thus attaching host-guest sites to the membrane surface. By harnessing the excellent binding affinity between β-CD attached to the membrane surface and adamantane, a supramolecular cell membrane-magnetic nanoparticle conjugate (CDM@AMNPs) was synthesized. Thanks to the nondestructive assembly of this strategy, CDM@AMNPs were endowed with a greater number of active binding sites, exhibiting efficient adsorption performance. This supramolecular conjugation strategy mediated by nonreceptor site-based host-guest interactions proposes a scalable and cell-friendly strategy for the development of highly efficient CNPs.

Characterization of a Peptidoglycan-Degrading Protein: Biochemical and Antimicrobial Characteristics, Antibiotic Synergism, and Delivery System Innovation.

The global health threat posed by antibiotic resistance has led to new research involving bacteriophage-encoded enzymes. This study characterized a new peptidoglycan-degrading protein and evaluated its synergism with colistin and its antimicrobial efficacy when conjugated with polycationic-polymer nanoparticles. The gene that codes for endolysin in the vB_PaeM_USP2, a Pseudomonas aeruginosa bacteriophage, was cloned and expressed in Escherichia coli. The recombinant endolysin (rEnd2) was purified and its biochemical properties were determined using peptidoglycan substrate. The enzymatic activity was measured through peptidoglycan layer degradation and a decrease in turbidity of permeabilized Gram-negative bacteria. The antimicrobial activity of rEnd2, alone and in combination with colistin, was evaluated by checkerboard assay. The antibacterial activity of the cationic lipid oleylamine (OAM) conjugated with rEnd2 (OAM-rEnd2) was evaluated by time killing assay. The rEnd2 is structurally analogue with other endolysins and showed muramidase activity. The rEnd2 maintained higher activity between pH 6.0 to 7.5, had maximum activity at 35 °C, and was not affected by chaotropic and reducing reagents. It was sensitive to an increase in surfactant concentration, being inactivated by sodium dodecyl sulfate and cetyltrimethylammonium bromide. Ions exhibited neither a positive nor a negative effect on enzyme activity. The rEnd2 showed clear muralytic activity and decreased turbidity of permeabilized Gram-negative bacteria. However, it did not control bacterial growth despite the combination with an antibiotic and its complexation with polycation (OAM-rEnd2 nanoparticle conjugate). The rEnd2 did not show clear antimicrobial activity suggesting further optimization of conditions for its activity or engineering and modification.

Ready-To-Use Microwave Sensor Modified by Antibody-AuNPs Nanoconjugate for Highly Sensitive and Selective Detection of the SARS-CoV-2 Virus.

The COVID-19 outbreak has led to notable developments in point-of-care (POC) diagnostic devices, as they can be valuable resources in identifying and managing the spread of the pandemic. Currently, the majority of techniques demand advanced laboratory equipment and professionals to execute precise, efficient, accurate, and sensitive testing. In this work, we report a new method to significantly enhance the sensitivity of microwave sensing of the SARS-CoV-2 virus by functionalizing the sensor surface using anti-SARS-CoV-2 spike antibody-gold nanoparticle (AuNPs) conjugates. AuNPs were surface-functionalized with the antispike antibody by EDC/NHS chemistry via PEG as a linker to form the conjugate (Ab-PEG-AuNPs). The Ab-PEG-AuNPs nanoconjugate was then coated onto the sensor through APTES and used for selectively capturing the spike protein on the SARS-CoV-2 virus. The sensing performance of the modified sensor was demonstrated via both experimental measurements and numerical simulations. Our sensor exhibited high sensitivity, achieving a limit of detection of 1,000 copies/mL of the SARS-CoV-2 virus within a 60 min time frame while requiring a minimal sample volume of 100 μL. The sensor exhibits outstanding specificity in distinguishing SARS-CoV-2 from other viruses, including influenza A and B, SARS-CoV-1, and MERS-CoV. Overall, this sensor provides a sensitive and label-free alternative for COVID-19 POC diagnosis.

Dimethylcurcumin-loaded methoxypolyethylene glycol-dimethylcurcumin conjugate nanoparticles: preparation, characterization and in vitro antitumor study

Dimethylcurcumin-loaded methoxypolyethylene glycol-dimethylcurcumin conjugate nanoparticles: preparation, characterization and in vitro antitumor study

Development of aptamer-based lateral flow devices for rapid detection of SARS-CoV-2 S protein and uncertainty assessment

The outbreak and spread of COVID-19 have highlighted the urgent need for early diagnosis of SARS-CoV-2. Nucleic acid testing as an authoritative tool, is cumbersome, time-consuming, and easy to cross-infect, while the available antibody self-testing kits are deficient in sensitivity and stability. In this study, we developed competitive aptamer-based lateral flow devices (Apt-LFDs) for the quantitative detection of SARS-CoV-2 spike (S) protein. Molecular docking simulation was used to analyze the active binding sites of the aptamer to S protein, guiding complementary DNA (cDNA) design. Then a highly efficient freezing strategy was applied for the conjugation of gold nanoparticles (AuNPs) and DNA probes. Under optimal conditions, the linear range of the constructed Apt-LFDs was 0.1–1 μg/mL, and the limit of detection (LOD) was 51.81 ng/mL. The cross-reactivity test and stability test of the Apt-LFDs showed good specificity and reliability. The Apt-LFDs had recoveries ranging from 89.45 % to 117.12 % in pharyngeal swabs. Notably, the uncertainty of the analytical result was evaluated using a “bottom-up” approach. At a 95 % confidence level, the uncertainty report of (453.37±54.86) ng/mL with k = 2 was yielded. Overall, this study provides an important reference for the convenient and reliable detection of virus proteins based on LFDs.

Carboxy-PEG-thiol functionalized gold nanoparticle conjugates for the detection of SARS-CoV-2: Detection tools and analytical method development

Addressing the need for accessible SARS-CoV-2 testing, carboxy-PEG 12-thiol functionalized gold nanoparticles conjugates were developed for rapid point-of-care (POC) detection against SARS-CoV-2 spike protein, pseudo-SARS-CoV-2, and authentic Beta SARS-CoV-2 virus particles. These conjugates leverage gold nanoparticles (AuNPs) as signal transducers, cross-linked to either angiotensin-converting enzyme 2 (ACE2) or SARS-CoV-2 spike protein receptor-binding domain (RBD) antibodies as bioreceptors and showed a distinct color shift from pink to blue. To assess their POC feasibility, the conjugates were integrated into facemasks and breathalyzers, wherein aerosolized SARS-CoV-2 antigens were successfully detected, producing a color change within 10 and 30 minutes for the breathalyzer and facemask prototypes, respectively. Furthermore, we explored quantitative analysis using varying concentrations of SARS-CoV-2 spike protein. Both conjugates demonstrated a linear relationship between blue color intensity and virus concentration, with linear ranges of 0.08–0.6 ng/mL and 0.04–0.5 ng/mL, respectively. Low limits of detection and quantification were also achieved. They exhibited specificity, responding solely to SARS-CoV-2 even in complex matrices containing diverse proteins, including the SARS-CoV-1 spike protein. Precision tests yielded coefficient of variations below 2 %, showcasing their remarkable reproducibility. This work presents a promising approach for rapid, sensitive, and specific POC detection of SARS-CoV-2 paving the way for improved pandemic response and management.

Testing a Nanoparticle Reagent for Imaging Mass Cytometry.

Mass cytometry (MC), a powerful single-cell analysis technique, has limitations in detecting low-abundance biomarkers. Nanoparticle (NP) reagents offer the potential for enhancing sensitivity by carrying large numbers of heavy metal isotopes. Here, we report NP reporters for imaging mass cytometry (IMC) based on NaYF4:Yb3+/Er3+ NPs. A two-step ligand exchange was used to coat NP surfaces with either methoxy-PEG2K-neridronate (PEG-Ner) and/or poly(sulfobetaine methacrylate)-neridronate (PSBMA-Ner). Both modifications provided long-term colloidal stability in PBS buffer. IMC measurements on tonsil tissue showed that PSBMA-Ner or a 1:1 mixture of PSBMA-Ner + PEG-Ner effectively suppressed nonspecific binding (NSB) at 2 × 1010 NPs/mL, unlike PEG-Ner alone. However, breast cancer tissue samples showed increased NSB at titers above 2 × 1010 NPs/mL. Reduced NSB with mixed PEG-Ner and PSBMA-Ner coatings opens the door for using heterobifunctional PEGs for the development of NP conjugates with bioaffinity agents, enabling more sensitive and specific MC analyses.