Unlocking the power of optical imaging in the second biological window: Structuring near-infrared II materials from organic molecules to nanoparticles

Biomedical imaging techniques play a crucial role in clinical diagnosis, surgical intervention, and prognosis. Fluorescence imaging in the second biological window (second near-infrared [NIR-II]; 1000-1700 nm) has attracted attention recently. NIR-II fluorescence imaging offers unique advantages in terms of reduced photon scattering, deep tissue penetration, high sensitivity, and many others. A host of materials, including small organic molecules, single-walled carbon nanotubes, polymeric and rare-earth-doped nanoparticles, have been explored as NIR-II emitting fluorescent probes. Efficient and viable approaches to design and develop fluorescence probes with tunable photophysical properties without compromising other key features are of paramount importance. Various chemical strategies are explored to increase the quantum yield of these imaging agents without compromising their spatiotemporal resolution, specificity, and tissue penetration capabilities. This review summarizes the strategies implemented to design and synthesize NIR-II emitting nanoparticles and small organic molecule-based fluorescent probes for applications in the biomedical field. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Implantable Materials and Surgical Technologies > Nanoscale Tools and Techniques in Surgery.

Emerging biomedical applications of polyaspartic acid-derived biodegradable polyelectrolytes and polyelectrolyte complexes

A summary of positive biomedical attributes of biodegradable polyelectrolytes (PELs) prepared from aspartic acid is provided. The utility of these PELs in emerging applications such as biomineralization modulators, antimycobacterials, biocompatible cell encapsulants and tissue adhesives is highlighted.

Self-Stabilized Hyaluronate Nanogel for Intracellular Codelivery of Doxorubicin and Cisplatin to Osteosarcoma

Osteosarcoma is one of the most serious bone malignancies with rapid speed of deterioration and low survival rate in children and teenagers. Chemotherapy is an important treatment for osteosarcoma, while the conventional small-molecule therapeutics exhibit low efficacies and severe side effects in the clinic. Drug-delivery platforms based on nanotechnology, particularly for self-stabilized delivery platforms with prolonged blood circulation, enhanced intratumoral accumulation, improved antitumor efficacy, and diminished side effects, may break the deadlock on osteosarcoma chemotherapy. Here, a cisplatin (CDDP)-crosslinked hyaluronic acid (HA) nanogel (CDDPHANG) is prepared for effective delivery of doxorubicin (DOX) to treat osteosarcoma. Importantly, both DOX and CDDP have led clinically used antitumor drugs, and CDDP acts as a crosslinker and ancillary anticarcinogen to prevent the premature release of DOX and to achieve synergistic therapeutic performance. Because of the enhanced stability of the nanogel, this CDDP-crosslinked DOX-loaded nanomedicine (CDDPHANG/DOX) exhibits an obviously prolonged circulation time compared to free drugs. Moreover, after valid tumor accumulation, DOX and CDDP are synergistically delivered into the tumor cells and synchronously released into the intracellular acidic environment. Based on the synergistic apoptosis-inducing effects of DOX and CDDP, CDDPHANG/DOX reveals an evidently enhanced antitumor efficacy compared to free drugs and their combination, indicating its great prospects for the chemotherapy of osteosarcoma.

A pH-responsive nanoprobe for turn-on 19F-magnetic resonance imaging

A pH-responsive MRI nanoprobe was developed by partially replacing organic linkers in ZIF-8, which displays pH-responsive in vivo¹⁹F MRI ability.

Multifunctional nanoprobes for both fluorescence and 19F magnetic resonance imaging

Fluorescence is widely used for cell imaging due to its high sensitivity and rich color choice but limited for in vivo imaging because of its low light penetration. Meanwhile, magnetic resonance imaging (MRI) is widely applied for in vivo diagnosis but not suitable for cell imaging because of its low resolution. Compared to ¹H-MRI, ¹⁹F-MRI is more suitable for clinical application due to its high sensitivity but fabricating ¹⁹F-MRI probes is a great challenge. Therefore, it is highly desirable to develop a dual-modal imaging probe for both cell fluorescence imaging and in vivo¹⁹F-MRI with high sensitivity and deep penetration. In this study, ¹⁹F moiety loaded nanocomposites with an organic fluorescent core were successfully prepared via a facile strategy by encapsulating organic dyes with oleylamine-functionalized polysuccinimide and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDTES). The aggregation of organic fluorescent dyes in the core results in significant fluorescence for optical imaging, while the ¹⁹F moieties on PDTES allow for simultaneous ¹⁹F MRI. Moreover, the nanocomposites exhibited high water dispersibility and excellent biocompatibility. These properties make them promising for both cell imaging and in vivo imaging applications.