Highly Fluorescent Magnetic Nanobeads with a Remarkable Stokes Shift as Labels for Enhanced Detection in Immunoassays

Antibody-Based Array for Tacrolimus Immunosuppressant Monitoring with Planar Plastic Waveguides Activated with an Aminodextran-Lipase Conjugate

Cyclic olefin copolymers (COC; e.g., Zeonor, Topas, Arton, etc.) are materials with outstanding properties for developing point-of-care systems; however, the lack of functional groups in their native form makes their application challenging. This work evaluates different strategies to functionalize commercially available Zeonor substrates, including oxygen plasma treatment, photochemical grafting, and direct surface amination using an amino dextran-lipase conjugate (ADLC). The modified surfaces were characterized by contact angle measurements, Fourier transform infrared-attenuated total reflection analysis, and fluorescence assays based on evanescent wave excitation. The bioaffinity activation through the ADLC approach results in a fast, simple, and reproducible approach that can be used further to conjugate carboxylated small molecules (e.g., haptens). The usefulness of this approach has been demonstrated by the development of a heterogeneous fluorescence immunoassay to detect tacrolimus (FK506) immunosuppressant drug using an array biosensor platform based on evanescence wave laser excitation and Zeonor-ADLC substrates. Surface modification with ADLC-bearing FK506 provides a 3D layer that efficiently leads to a remarkably low limit of detection (0.02 ng/mL) and IC50 (0.9 ng/mL) together with a wide dynamic range (0.07-11.3 ng/mL).

Magnetic Janus micromotors for fluorescence biosensing of tacrolimus in oral fluids

Tacrolimus (FK506) is a macrolide lactone immunosuppressive drug that is commonly used in transplanted patients to avoid organ rejection. FK506 exhibits high inter- and intra-patient pharmacokinetic variability, making monitoring necessary for organ graft survival. This work describes the development of a novel bioassay for monitoring FK506. The bioassay is based on using polycaprolactone-based (PCL) magnetic Janus micromotors and a recombinant chimera receptor that incorporates the immunophilin tacrolimus binding protein 1A (FKBP1A) tagged with Emerald Green Fluorescent Protein (EmGFP). The approach relies on a fluorescence competitive bioassay between the drug and the micromotors decorated with a carboxylated FK506 toward the specific site of the fluorescent immunophilin. The proposed homogeneous assay could be performed in a single step without washing steps to separate the unbound receptor. The proposed approach fits the therapeutic requirements, showing a limit of detection of 0.8 ng/mL and a wide dynamic range of up to 90 ng/mL. Assay selectivity was evaluated by measuring the competitive inhibition curves with other immunosuppressive drugs usually co-administered with FK506. The magnetic propulsion mechanism allows for efficient operation in raw samples without damaging the biological binding receptor (FKBP1A-EmGFP). The enhanced target recognition and micromixing strategies hold considerable potential for FK506 monitoring in practical clinical use.

New insights from poly-lactic acid and ionomer films coupled with recombinant antibodies for processing sexed-sorting bovine sperm

In this study, the efficacy of ionomers and poly-lactic acid (PLA) as an alternative solid material combined with scFv antibodies specific to bovine Y-sperm (Y-scFv) was studied to create a novel method of sexing technology. The coupling efficiency of Y-scFv to the surface of PLA, Na+ and Zn2+ ionomer film was between 2 and 8 mg/mL. Fourier transform infrared spectra confirm that Y-scFv was bound with a carboxylic acid group in each film. Therefore, Na+, Zn2+ ionomers and PLA films conjugated with 4 and 8 mg/mL Y-scFv showed the highest concentration of Y-sperm in the eluted fraction. Considering that the elute fraction was enriched Y-sperm fraction, it contained 67.70-77.94 % of the Y-sperm ratio related to the produced supernatant fraction, which contained up to 69.31-76.01 % enriched X-sperm. In addition, the sperm quality after the sexing process was analyzed by CASA and imaging flow cytometry, which showed that each polymer did not have a negative effect on sperm motility and acrosome integrity for X-sperm. The capacity of ionomer and PLA combined with Y-scFv are used for bovine sperm sexing.

Artificial Intelligence-Assisted Digital Immunoassay Based on a Programmable-Particle-Decoding Technique for Multitarget Ultrasensitive Detection

The development of a multitarget ultrasensitive immunoassay is significant to fields such as medical research, clinical diagnosis, and food safety inspection. In this study, an artificial intelligence (AI)-assisted programmable-particle-decoding technique (APT)-based digital immunoassay system was developed to perform multitarget ultrasensitive detection. Multitarget was encoded by programmable polystyrene (PS) microspheres with different characteristics (particle size and number), and subsequent visible signals were recorded under an optical microscope after the immune reaction. The resultant images were further analyzed using a customized, AI-based computer vision technique to decode the intrinsic properties of polystyrene microspheres and to reveal the types and concentrations of targets. Our strategy has successfully detected multiple inflammatory markers in clinical serum and antibiotics with a broad detection range from pg/mL to μg/mL without extra signal amplification and conversion. An AI-based digital immunoassay system exhibits great potential to be used for the next generation of multitarget detection in disease screening for candidate patients.

Ultrasensitive Sandwich-Type SERS-Biosensor-Based Dual Plasmonic Superstructure for Detection of Tacrolimus in Patients

Tacrolimus (FK506) is widely used in the prevention of organ transplant rejection and the treatment of autoimmune diseases, but it is difficult to detect within the low and narrow concentration range in practical clinical fields. A magnetic plasmonic superstructure-targets-plasmonic superstructure-based sandwich-type SERS biosensor is presented here to ultrasensitively detect FK506 in the blood of organ transplant patients. The spiky Fe₃O₄@SiO₂@Ag flower magnetic superstructure and hollow Ag@Au superstructure enhanced the SERS signals by providing rich sharp tips, cavities, and abundant hot spot gaps. And the magnetic feature makes it easy to concentrate and separate the biological target. Using the designed sandwich-type SERS biosensor, FK506 could be detected within a range of 0.5-20 ng/mL with a detection limit of 0.33 ng/mL. All results indicated that the sandwich-type SERS biosensor has good stability, sensitivity, and anti-interference properties. It is noteworthy that this allowed us to successfully analyze FK506 in the blood of transplant patients, which is in strong agreement with the clinical results. Consequently, the attractive sandwich-type SERS biosensor can be used for the detection of FK506 in real samples, which is promising for clinical diagnosis.

BODIPY-Based Nanomaterials—Sensing and Biomedical Applications

Cancerous diseases are rightfully considered among the most lethal, which have a consistently negative effect when considering official statistics in regular health reports around the globe. Nowadays, metallic nanoparticles can be potentially applied in medicine as active pharmaceuticals, adjustable carriers, or distinctive enhancers of physicochemical properties if combined with other drugs. Boron dipyrromethene (BODIPY) molecules have been considered for future applications in theranostics in the oncology field, thus expanding the potential of conceivable applicability. Hence, taking into account positive practical features of both metal-based nanostructures and BODIPY derivatives, the present study aims to gather recent results connected to BODIPY-conjugated metallic nanoparticles. This is with respect to their expediency in the diagnosis and treatment of tumor ailments as well as in sensing of heavy metals. To fulfill the designated objectives, multiple research documents were analyzed concerning the latest discoveries within the scope of BODIPY-based nanomaterials with particular emphasis on their utilization for diagnostical sensing as well as cancer diagnostics and therapy. In addition, collected examples of mentioned conjugates were presented in order to draw the attention of the scientific community to their practical applications, elucidate the topic in a consistent manner, and inspire fellow researchers for new findings.

An integrated device for fast and sensitive immunosuppressant detection

The present paper describes a compact point of care (POC) optical device for therapeutic drug monitoring (TDM). The core of the device is a disposable plastic chip where an immunoassay for the determination of immunosuppressants takes place. The chip is designed in order to have ten parallel microchannels allowing the simultaneous detection of more than one analyte with replicate measurements. The device is equipped with a microfluidic system, which provides sample mixing with the necessary chemicals and pumping samples, reagents and buffers into the measurement chip, and with integrated thin film amorphous silicon photodiodes for the fluorescence detection. Submicrometric fluorescent magnetic particles are used as support in the immunoassay in order to improve the efficiency of the assay. In particular, the magnetic feature is used to concentrate the antibody onto the sensing layer leading to a much faster implementation of the assay, while the fluorescent feature is used to increase the optical signal leading to a larger optical dynamic change and consequently a better sensitivity and a lower limit of detection. The design and development of the whole integrated optical device are here illustrated. In addition, detection of mycophenolic acid and cyclosporine A in spiked solutions and in microdialysate samples from patient blood with the implemented device are reported.

Colorful Luminescent Magnetic Supraparticles: Expanding the Applicability, Information Capacity, and Security of Micrometer-Scaled Identification Taggants by Dual-Spectral Encoding

(Sub)micrometer-scaled identification (ID) taggants enable direct identification of arbitrary goods, thereby opening up application fields based on the possibility of tracking, tracing, and anti-counterfeiting. Due to their small dimensions, these taggants can equip in principle even the smallest subcomponents or raw materials with information. To achieve the demanded applicability, the mostly used optically encoded ID taggants must be further improved. Here, micrometer-scaled supraparticles with spectrally encoded luminescent and magnetically encoded signal characteristics are reported. They are produced in a readily customizable bottom-up fabrication procedure that enables precise adjustment of luminescent and magnetic properties on multiple hierarchy levels. The incorporation of commonly used magnetic nanoparticles and fluorescent dyes, respectively, into polymer nanocomposite particles, establishes a convenient toolbox of magnetic and luminescent building blocks. The subsequent assembly of selected building blocks in the desired ratios into supraparticles grants for all the flexibility to freely adjust both signal characteristics. The obtained spectrally resolved visible luminescent and invisible magnetic ID signatures are complementary in nature, thus expanding applicability and information security compared to recently reported optical- or magnetic-encoded taggants. Additionally, the introduced ID taggant supraparticles can significantly enhance the coding capacity. Therefore, the introduced supraparticles are considered as next-generation ID taggants.

Overview of therapeutic drug monitoring of immunosuppressive drugs: Analytical and clinical practices

Immunosuppressant drugs (ISDs) play a key role in short-term patient survival together with very low acute allograft rejection rates in transplant recipients. Due to the narrow therapeutic index and large inter-patient pharmacokinetic variability of ISDs, therapeutic drug monitoring (TDM) is needed to dose adjustment for each patient (personalized medicine approach) to avoid treatment failure or side effects of the therapy. To achieve this, TDM needs to be done effectively. However, it would not be possible without the proper clinical practice and analytical tools. The purpose of this review is to provide a guide to establish reliable TDM, followed by a critical overview of the current analytical methods and clinical practices for the TDM of ISDs, and to discuss some of the main practical aspects of the TDM.

Point-of-Care Therapeutic Drug Monitoring for Precision Dosing of Immunosuppressive Drugs

BACKGROUND

Immunosuppressive drugs (ISD) are an essential tool in the treatment of transplant rejection and immune-mediated diseases. Therapeutic drug monitoring (TDM) for determination of ISD concentrations in biological samples is an important instrument for dose personalization for improving efficacy while reducing side effects. While currently ISD concentration measurements are performed at specialized, centralized facilities, making the process complex and laborious for the patient, various innovative technical solutions have recently been proposed for bringing TDM to the point-of-care (POC).

CONTENT

In this review, we evaluate current ISD-TDM and its value, limitations, and proposed implementations. Then, we discuss the potential of POC-TDM in the era of personalized medicine, and provide an updated review on the unmet needs and available technological solutions for the development of POC-TDM devices for ISD monitoring. Finally, we provide concrete suggestions for the generation of a meaningful and more patient-centric process for ISD monitoring.

SUMMARY

POC-based ISD monitoring may improve clinical care by reducing turnaround time, by enabling more frequent measurements in order to obtain meaningful pharmacokinetic data (i.e., area under the curve) faster reaction in case of problems and by increasing patient convenience and compliance. The analysis of the ISD-TDM field prompts the evolution of POC testing toward the development of fully integrated platforms able to support clinical decision-making. We identify 4 major areas requiring careful combined implementation: patient usability, data meaningfulness, clinicians' acceptance, and cost-effectiveness.

Early Detection of SARS-CoV-2 Seroconversion in Humans with Aggregation-Induced Near-Infrared Emission Nanoparticle-Labeled Lateral Flow Immunoassay

An outbreak of coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses great threats to human health and the international economy. To reduce large-scale infection and transmission risk of SARS-CoV-2, a simple, rapid, and sensitive serological diagnostic method is urgently needed. Herein, an aggregation-induced emission (AIE) nanoparticle (AIE810NP, λem = 810 nm)-labeled lateral flow immunoassay was designed for early detection of immunoglobulin M (IgM) and immunoglobulin G (IgG) against SARS-CoV-2 in clinical serum samples. Using a near-infrared (NIR) AIE nanoparticle as the fluorescent reporter (△λ = 145 nm), the autofluorescence from the nitrocellulose membrane and biosample and the excitation background noise were effectively eliminated. After optimization, the limit of detection of IgM and IgG is 0.236 and 0.125 μg mL-1, respectively, commensurate with that of the enzyme-linked immunosorbent assay (ELISA) (0.040 and 0.039 μg mL-1). The sensitivity of the proposed AIE810NP-based test strip for detecting IgM and IgG is 78 and 95% (172 serum samples), commensurate with that of ELISA (85 and 95%) and better than that of a commercial colloidal gold nanoparticle (AuNP)-based test strip (41 and 85%). Importantly, the time of detecting IgM or IgG with an AIE810NP-based test strip in sequential clinical samples is 1-7 days after symptom onset, which is significantly earlier than that with a AuNP-based test strip (8-15 days). Therefore, the NIR-emissive AIE nanoparticle-labeled lateral flow immunoassay holds great potential for early detection of IgM and IgG in a seroconversion window period.

A novel magneto-gold nanohybrid-enhanced lateral flow immunoassay for ultrasensitive and rapid detection of ochratoxin A in grape juice

Conventional gold nanoparticle-based lateral flow immunoassay (LFIA) usually suffers a huge challenge in measuring target concentration in food matrices with dark color because of its poor resistance to the background matrix and color interference. To address this issue, we first report a novel bifunctional magneto-gold nanohybrid (MGNH) for the simultaneous magnetic separation and colorimetric target sensing by integrating MGNHs into LFIA. Under optimum conditions, an ultrasensitive detection of ochratoxin A (OTA) in grape juice was achieved with a limit of detection at 0.094 ng mL^-1. The average recoveries of this MGNH-LFIA ranged from 92.31% to 108.97% with a coefficient of variation of below 12%. The excellent selectivity of our MGNH-LFIA against OTA was demonstrated. Besides, our MGNH-LFIA is comparable to liquid chromatography coupled with mass spectrometry in terms of accuracy, reproducibility, and practicability. The designed MGNH-LFIA platform is readily extended for improving other small molecule detection in food samples.

Multifunctional Magnetic-Fluorescent Nanoparticle: Fabrication, Bioimaging, and Potential Antibacterial Applications

Magnetic-fluorescent nanoparticles integrating imaging and therapeutic capabilities have unparalleled advantages in the biomedical applications. Apart from the dual ability of unique biomolecular fluorescent recognition and magnetic modes, the nanoparticle also endows combined effective therapies with high physiological stability, long-term imaging, rapid response time, and excellent circulation ability. Herein, we developed a carboxyl-functionalized magnetic nanoparticle that was further functionalized by polydopamine (PDA) and Schiff base ligand (3-aminopyridine-2-carboxaldehyde N(4)-methylthiosemicarbazone, HL) to form multilayered coating single nanoparticles (Fe₃O₄@PDA@HL). Our work showed that the aggregation-induced emission (AIE) effect could be produced by embedding In³⁺ into the Fe₃O₄@PDA@HL nanostructure, which offered a new opportunity for utilization as a fluorescent detection and therapeutic platform. Cellular fluorescent imaging experiments provided bacterial cell biodistribution, demonstrating their excellent luminescent performance, magnetic aggregation, and separation capability. We simultaneously confirmed that the synergistic antibacterial effect was closely related to both Fe₃O₄@PDA@HL and In³⁺, leading to the disruption of membrane integrity and the leakage of intracellular components, thus inducing bacterial death. This approach presented in our work could promote the development of future bioimaging and clinical therapy applications.

Manganese dioxide nanosheets: from preparation to biomedical applications

Advancements in nanotechnology and molecular biology have promoted the development of a diverse range of models to intervene in various disorders (from diagnosis to treatment and even theranostics). Manganese dioxide nanosheets (MnO₂ NSs), a typical two-dimensional (2D) transition metal oxide of nanomaterial that possesses unique structure and distinct properties have been employed in multiple disciplines in recent decades, especially in the field of biomedicine, including biocatalysis, fluorescence sensing, magnetic resonance imaging and cargo-loading functionality. A brief overview of the different synthetic methodologies for MnO₂ NSs and their state-of-the-art biomedical applications is presented below, as well as the challenges and future perspectives of MnO₂ NSs.