Luminescence Sensing of Biomacromolecules Heparin and Protamine in 100% Human Serum and Plasma by Supramolecular Polymeric Assemblies

Tricarbonylrhenium(I) complexes with aggregation-induced phosphorescence emission (AIPE) properties: Application to the selective detection of heparin and its main contaminant

Phosphorescent tricarbonylrhenium(I) complexes that are more emissive in the aggregate state than in solution could be very valuable probes for biological analyses, but their development is delicate. The present work focuses on the synthesis and spectroscopic study of three new complexes that differ by the nature of their positively charged substituent. The dissolved complexes were very weakly emissive. Due to electrostatic interaction and aggregation, they showed a strong aggregation-induced phosphorescence enhancement (AIPE) effect in the presence of heparin, a polyanionic macromolecule of biological interest, and a weaker effect in the presence of chondroitin sulfate, which contains fewer negative charges. The magnitude of the AIPE effect depended on the nature and number of the cationic groups borne by the complex. However, it was weaker than expected from the behavior of the parent neutral complex studied in a conventional acetonitrile/water system, which highlights the challenge of accurately predicting solid-state emission properties for this class of molecules. This work introduces rhenium(I) complexes in the field of AIPE-active probes for the detection of polyanionic biomolecules.

Sensitive fluorescence detection of heparin based on the assembly of a cationic surfactant and an anionic dye

A highly sensitive sensing system for heparin has been developed using a synthetic fluorescent dye, L-phenylalanyl-L-phenylalanine-modified dansyl (FF-Dns), in combination with the cationic surfactant octadecyltrimethylammonium chloride (OTAC). At low concentrations, FF-Dns and OTAC self-assemble, leading to a reduction in the fluorescence intensity of the dansyl group. However, upon the introduction of heparin, the electrostatic binding between OTAC and heparin disrupts the self-assembly, effectively releasing FF-Dns and restoring its fluorescence. This system shows exceptional selectivity for heparin over a range of potential interfering substances. The detection limit for heparin was determined to be 31.7 ng mL-1, with a linear response range of 0-4 μg mL-1. In addition, a "turn-on" fluorescence-based assay platform using FF-Dns/OTAC was successfully established in 0.2% serum with a detection limit of 30.57 ng mL-1 and a linear span of 0-5 μg mL-1. In addition, the FF-Dns/OTAC/heparin mixture was identified as a potential sensing platform for protamine, exploiting the strong binding affinity between protamine and heparin.

Ratiometric luminescence sensing of bio-macromolecules via highly sensitive templated pyrene-based nanoGUMBOS

A series of pyrene-based ionic liquids, comprises a group of uniform materials based on organic salts (GUMBOS), were synthesized by incorporating pyrene butyrate with quaternary alkyl phosphonium or ammonium cations via ion exchange reaction and by virtue of a variation in alkyl chain-length. Water-suspended crystalline pyrene-assimilated nanoparticles (nanoGUMBOS) were subsequently fabricated from the prepared GUMBOS via reprecipitation method. Photophysical and microscopic measurements were performed to confirm the crystalline molecular-level stacking of pyrene fluorophores inside the nanoparticles. The pyrene moieties within the nanoGUMBOS showed a tendency for enhanced self-association upon photo-excitation, resulting in a novel excited-state aggregation-induced emission (ESAIE). Due to the bathochromically-shifted strong aggregation-induced emission, these nanoGUMBOS are further employed in the sensitive and selective ratiometric detection of biomacromolecules in aqueous and serum albumin media. As the excessive use of some biomacromolecules (heparin and protamine) can lead to undesired side-effects in living systems, hence their detection can be very crucial. In most cases, interaction with biomacromolecules like heparin facilitates the formation of excimer species in pyrene systems, but to our utter surprise, here we observed the opposite phenomenon of excimer disintegration. This presents a convenient method for detecting heparin in aqueous and serum albumin media. Furthermore, using the nanoGUMBOS-heparin complex, we can also detect protamine. A detailed study of the detection mechanism is presented in this report.

An Aggregation-Induced Room Temperature Phosphorescence Probe for the Efficient and Selective Detection of Heparin and Protamine

Heparin is a vital macromolecule that regulates blood coagulation, while protamine is an essential polypeptide clinically used to counteract heparin overdose. Detecting both heparin and its antidote protamine under physiological conditions is crucial for biological and clinical applications. This report introduces a cucurbituril[8] (CB[8])-based phosphorescent probe for their detection. The method employs a nanoassembly induced phosphorescence switch-on mechanism for heparin sensing and a disassembly induced phosphorescence switch-off approach for protamine detection. An arginine-rich guest forms a supramolecular complex with heparin, enhancing phosphorescence under secondary confinement and enabling its detection. Conversely, protamine sulfate, as a stronger competitor for heparin, disrupts the probe-heparin aggregates, leading to emission quenching and protamine sensing. This sensor demonstrated high selectivity in detecting both analytes in biological samples, such as human blood serum and urine. The detection limits for heparin and protamine were determined to be 61 and 82 ng/mL in 10% HBS, respectively.

Amidine-functionalized aggregation-induced emission luminogen and a 3D-printed digital sensor platform for ultrafast and visual detection of heparin

BACKGROUND

Heparin is a widely used anticoagulant in clinic. However, improper dosing can increase the risk of thromboembolic events, potentially leading to life-threatening complications. Clinic monitoring of heparin is very important for its use safety. Rapid and accurate point-of-care testing can significantly reduce the risk of thrombotic events. The detection of heparin using fluorescent probes has emerged as a significant area of research, driven by the need for rapid, sensitive, and selective methods for monitoring this crucial anticoagulant in clinical settings. However, the absence of convenient and user-friendly heparin testing methods continues to pose a challenge.

RESULTS

In this work, a tetraphenylethylene derivatives with four amidine active groups (TPE-4+) was prepared. TPE-4+ has obvious aggregation-induced emission (AIE) effect on the heparin with a 127-fold enhancement occurring within just 3 s. The molecular docking simulation showed that TPE-4+ was closely embedded in the heparin by the electrostatic force between four amidine of TPE-4+ and sulfate ester group of heparin, restricted intramolecular motion of TPE-4+, and causing obvious AIE features. The fluorescence intensity of TPE-4+ was line with the concentration of heparin in the range of 0-2.0 U/mL with a lowest detection limit of 0.0038 U/mL. The possible interference in the serum samples had no influence on the determination of heparin. Using 3D printing technology, a compact, portable digital sensor platform for straightforward monitoring of heparin levels was fabricated.

SIGNIFICANCE

The proposed innovative platform provides a powerful tool to make portable and real-time monitoring of heparin possible, and thereby contributing to achieve point-of-care testing and decrease the risk of thrombotic events. This novel method of combining the probe with the sensing platform simplifies the detection process and enhances patient care by providing more accurate diagnostic capabilities.

A hydrogel-based ratiometric fluorescent sensor relying on rhodamine B labelled AIE-featured hyperbranched poly(amido amine) for heparin detection

The fluorescent flexible sensor for point-of-care quantification of clinical anticoagulant drug, Heparin (Hep), is still an urgent need of breakthrough. In this research, a hyperbranched poly(amido amine) (HPA) was decorated with tetraphenylethene (TPE) and Rhodamine B (RhB), constructing a ratiometric fluorescent sensor (TR-HPA) for Hep. When the sensor was exposed to Hep, the TPE units within the probe skeleton would aggregate, resulting in an increasing fluorescent emission at 483 nm. The 580 nm of fluorescence came from RhB enhance, simultaneously, due to the fluorescence resonance energy transfer. As a result, there are two good linear correlation between the fluorescence emission ratio (E483/E580) of TR-HPA and the Hep concentration over a range of 0-1.0 μM, with a low limit of detection of 3.0 nM. Furthermore, we incorporate the TR-HPA probe into a polyvinyl alcohol (PVA) hydrogel matrix to create a flexible fluorescent sensing system platform, denoted as TR-HPA/PVA. This approach offers a straightforward visual detection method by causing a fluorescence color change from pink to blue when trace amounts of Hep are present. The hydrogel-based fluorescent sensor streamlines the detection procedures for Hep in biomedical applications. It shows great potential in rapid and point-of-care human blood clotting condition monitoring, making it suitable for next-generation wearable medical devices.