Protein-modified conjugated polymer nanoparticles with strong near-infrared absorption: a novel nanoplatform to design multifunctional nanoprobes for dual-modal photoacoustic and fluorescence imaging

Aggregation-induced emission nanoparticles with improved optical absorption for boosting fluorescence signal of tumors in vivo

Nanomaterial development has been extensively investigated for several decades to realize sensitive and accurate imaging of tumors in vivo. The manufacturing of nanoparticles with highly efficient tumor targeting and excellent optical properties is still an important research topic. The structure and composition ratio of materials that decisively contribute to the brightness and size of nanoparticles have a great influence on image sensitivity and tumor targeting efficiency. In this study, we developed aggregation-induced emission (AIE) nanoparticles with a widened light absorption window (nanoPMeOCN/BDP) to enable sensitive in vivo tumor imaging. The signal of nanoparticles is enhanced by integrating a high-density AIE polymer (PMeOCN) and light-absorbing fluorescent dye (BDP) in a nanoscopic space. BDP not only improves the light absorption of particles but also enhances the fluorescence signal of particles by effectively transferring absorbed energy to PMeOCN. The physically blended nanoPMeOCN/BDP show strong light absorption and improved sensitivity for the imaging of biological tissues because of their excellent optical performance compared to nanoPMeOCN of similar nanosizes (∼19 nm in size). In vivo imaging results further confirm that nanoPMeOCN/BDP can provide amplified signals with the successful accumulation of tumor tissue through the enhanced permeability and retention effect. We expect that the design strategy of nanoparticles with improved light absorption will provide a simple and general method for improving the accuracy of disease diagnosis.

Engineering Molecular Probes for In Vivo Near-Infrared Fluorescence/Photoacoustic Duplex Imaging of Human Neutrophil Elastase

Early detection of human neutrophil elastase (HNE), the potential biomarker of lung cancer, is crucial for the accurate diagnosis and evaluation of lung cancer. Currently, little progress of HNE-activated probes has been made for in vivo imaging. Herein, assisted by probe-active pocket match engineering, we synthesized a series of near-infrared fluorescence (NIRF) and photoacoustic (PA) duplex imaging probes by conjugating diverse fluorinated amide chains onto hemi-cyanine. Finally, we identified that probe 2 (denoted as LET-8), with the pentafluoroethyl group, is a superior probe to detect HNE with the best selectivity as well as good response ability and thus successfully realized NIRF/PA duplex imaging of HNE activity both in vitro and in vivo.

Conjugated polymer nanoparticles and their nanohybrids as smart photoluminescent and photoresponsive material for biosensing, imaging, and theranostics

The emergence of conjugated polymers (CPs) has provided a pathway to attain smart multifunctional conjugated polymer nanoparticles (CPNs) with enhanced properties and diverse applications. CPNs based on π-extended CPs exhibit high fluorescence brightness, low cytotoxicity, excellent photostability, reactive oxygen species (ROS) generation ability, high photothermal conversion efficiency (PCE), etc. which endorse them as an excellent theranostic tool. Furthermore, the unique light-harvesting and energy transfer properties of CPNs enables their transformation into smart functional nanohybrids with augmented performance. Owing to such numerous features, simple preparation method and an easy separation process, the CPNs and their hybrids have been constantly rising as a frontrunner in the domain of medicine and much work has been done in the respective research area. This review summarizes the recent progress that has been made in the field of CPNs for biological and biomedical applications with special emphasis on biosensing, imaging, and theranostics. Following an introduction into the field, a first large section provides overview of the conventional as well as recently established synthetic methods for various types of CPNs. Then, the CPNs-based fluorometric assays for biomolecules based on different detection strategies have been described. Later on, examples of CPNs-based probes for imaging, both in vitro and in vivo using cancer cells and animal models have been explored. The next section highlighted the vital theranostic applications of CPNs and corresponding nanohybrids, mainly via imaging-guided photodynamic therapy (PDT), photothermal therapy (PTT) and drug delivery. The last section summarizes the current challenges and gives an outlook on the potential future trends on CPNs as advanced healthcare material.

Temperature-Feedback Nanoplatform for NIR-II Penta-Modal Imaging-Guided Synergistic Photothermal Therapy and CAR-NK Immunotherapy of Lung Cancer

In this study, to visually acquire all-round structural and functional information of lung cancer while performing synergistic photothermal therapy (PTT) and tumor-targeting immunotherapy, a theranostic nanoplatform that introduced upconversion nanoparticles (UCNPs) and IR-1048 dye into the lipid-aptamer nanostructrure (UCILA) is constructed. Interestingly, the IR-1048 dye grafted into the lipid bilayer can serve as the theranostic agent for photoacoustic imaging, optical coherence tomography angiography, photothermal imaging, and PTT in the second near infrared (NIR-II) window. In addition, loaded in the inner part of UCILA, UCNPs possess the superior luminescence property and high X-ray attenuation coefficient, which can act as contrast agents for computed tomography (CT) and thermo-sensitive up-conversion luminescence (UCL) imaging, enabling real-time tracking of metabolic activity of tumor and temperature-feedback PTT. Furthermore, under the complementary guidance of penta-modal imaging and an accurate monitoring of in situ temperature change during PTT, UCILA exhibits its excellent capability for ablating the lung tumor with minimal side effects. Meanwhile, synergistic CAR-NK immunotherapy is carried out specifically to eradicate any possible residual tumor cells after PTT. Therefore, the UCILA nanoplatform is demonstrated as a multifunctional theranostic agent for both penta-modal imaging and temperature-feedback PTT while conducting targeting immunotherapy of lung cancer.

Recent Advances of Bioresponsive Nano-Sized Contrast Agents for Ultra-High-Field Magnetic Resonance Imaging

The ultra-high-field magnetic resonance imaging (MRI) nowadays has been receiving enormous attention in both biomaterial research and clinical diagnosis. MRI contrast agents are generally comprising of T1-weighted and T2-weighted contrast agent types, where T1-weighted contrast agents show positive contrast enhancement with brighter images by decreasing the proton's longitudinal relaxation times and T2-weighted contrast agents show negative contrast enhancement with darker images by decreasing the proton's transverse relaxation times. To meet the incredible demand of MRI, ultra-high-field T2 MRI is gradually attracting the attention of research and medical needs owing to its high resolution and high accuracy for detection. It is anticipated that high field MRI contrast agents can achieve high performance in MRI imaging, where parameters of chemical composition, molecular structure and size of varied contrast agents show contrasted influence in each specific diagnostic test. This review firstly presents the recent advances of nanoparticle contrast agents for MRI. Moreover, multimodal molecular imaging with MRI for better monitoring is discussed during biological process. To fasten the process of developing better contrast agents, deep learning of artificial intelligent (AI) can be well-integrated into optimizing the crucial parameters of nanoparticle contrast agents and achieving high resolution MRI prior to the clinical applications. Finally, prospects and challenges are summarized.

Size-dependent fluorescence of conjugated polymer dots and correlation with the fluorescence in solution and in the solid phase of the polymer

Three conjugated polymers (CPs) were synthesized to obtain CPs with the same backbone but with different compositions of repeat units (phenylene and benzoselenadiazole (BSD)). The dominant composition of phenylene units and a smaller amount of BSD in the CP backbone enabled the CPs to emit different fluorescence colors according to their condition (solution or solid), which was caused by the difference in intermolecular electron transfer between CP backbones. Inspired by this, we fabricated polymer dots (Pdots) with various sizes using the CPs to control the number of CP chains within a spherical Pdot. This implied that smaller Pdots, where the chance of intermolecular electron transfer would be at a minimum, would accommodate fewer polymer chains than larger ones. The minimum chance for intermolecular electron transfer resulted in a short-wavelength emission, which was the identical emission color encountered in liquid CP solution. A more frequent intermolecular electron transfer was expected in larger Pdots, exhibiting long-wavelength emission, which was the same as observed in solid CPs. White-light-emitting Pdots that showed Commission Internationale de 1'Eclairage (CIE) coordinates of (0.34, 0.31) were fabricated simply by controlling the Pdot size.

Conjugated polymers as nanoparticle probes for fluorescence and photoacoustic imaging

In this review, the role of conjugated polymer nanoparticles (CPNs) in emerging bioimaging techniques is described.

Recent advances in cancer bioimaging using a rationally designed Raman reporter in combination with plasmonic gold

Gold nanomaterials (AuNMs) have been widely implemented for the purpose of bioimaging of cancer and tumor cells in combination with Raman spectral markers.