Radioactive and Fluorescent Dual Modality Cysteine Cathepsin B Activity-Based Probe for Cancer Theranostics

Cysteine cathepsin B (CTS-B) is a crucial enzyme that is overexpressed in numerous malignancies and contributes to the invasion and metastasis of cancer. Therefore, this study sets out to develop and evaluate an activity-based multimodality theranostic agent targeting CTS-B for cancer imaging and therapy. A CTS-B activity-based probe, BMX2, was synthesized and labeled efficiently with ⁶⁸Ga and ⁹⁰Y to produce ⁶⁸Ga-BMX2 for multimodality imaging and ⁹⁰Y-BMX2 for radiation therapy. The affinity and specificity of BMX2 binding with the CTS-B enzyme were determined by fluorescent western blots using recombined active human CTS-B enzyme (rh-CTS-B) and four cancer cell lines including HeLa, HepG2, MCF7, and U87MG, with CA074 as the CTS-B inhibitor for control. Confocal laser scanning microscope imaging and cell uptake measurement were also performed. Then, in vivo PET imaging and fluorescence imaging were acquired on HeLa xenografts. Finally, the therapeutic effect of ⁹⁰Y-BMX2 was tested. BMX2 could be specifically activated by rh-CTS-B and stably bound to the enzyme. The binding of BMX2 with CTS-B is time-dependent and enzyme concentration-dependent. Although CTS-B expression varied between cell lines, all showed significant uptake of BMX2 and ⁶⁸Ga-BMX2. In vivo optical and PET imaging showed a high tumor uptake of BMX2 and ⁶⁸Ga-BMX2 and accumulation for more than 24 h. ⁹⁰Y-BMX2 could significantly inhibit HeLa tumor growth. The development of ⁶⁸Ga/⁹⁰Y-BMX2, a radioactive and fluorescent dual modality theranostic agent, demonstrated an effective theranostic approach for PET diagnostic imaging, fluorescence imaging, and radionuclide therapy of cancers, which may have a potential for clinical translation for cancer theranostics in the future.

Stimuli-Responsive Aggregation-Induced Emission (AIE)-Active Polymers for Biomedical Applications

At high concentration or in the aggregated state, most of the traditional luminophores suffer from the general aggregation-caused quenching (ACQ) effect, which significantly limits their biomedical applications. On the contrary, a few fluorophores exhibit an aggregation-induced emission (AIE) feature which is just the opposite of ACQ. The luminophores with aggregation-induced emission (AIEgens) have exhibited noteworthy advantages to get tunable emission, excellent photostability, and biocompatibility. Incorporating AIEgens into polymer design has yielded diversified polymer systems with fascinating photophysical characteristics. Again, stimuli-responsive polymers are capable of undergoing chemical and/or physical property changes on receiving signals from single or multiple stimuli. The combination of the AIE property and stimuli responses in a single polymer platform provides a feasible and effective strategy for the development of smart polymers with promising biomedical applications. Herein, the advancements in stimuli-responsive polymers with AIE characteristics for biomedical applications are summarized. AIE-active polymers are first categorized into conventional π-π conjugated and nonconventional fluorophore systems and then subdivided based on various stimuli, such as pH, redox, enzyme, reactive oxygen species (ROS), and temperature. In each section, the design strategies of the smart polymers and their biomedical applications, including bioimaging, cancer theranostics, gene delivery, and antimicrobial examples, are introduced. The current challenges and future perspectives of this field are also stated at the end of this review article.

Degradable Magnetic Nanoplatform with Hydroxide Ions Triggered Photoacoustic, MR Imaging, and Photothermal Conversion for Precise Cancer Theranostic

Theranostic agents based on inorganic nanomaterials are still suffered from the nonbiodegradable substances with long-term retention in body and unavoidable biological toxicity, as well as nonspecificity biodistribution with potential damage toward normal tissues. Here, we develop magnetic ions (Fe^III, Fe^II, Gd^III, Mn^II, and Mn^III) coordinated nanoplatform (MICN) with framework structure and modify them with PEG (MICN-PEG). Notably, MICN-PEG demonstrates hydroxide ions (OH^-) triggered the structure collapse along with responsive near-infrared photoacoustic (PA) signal, magnetic resonance imaging (MRI), and photothermal therapy (PTT) performances. Thereby, MICN-PEG is able to remain stable in tumors and exert excellent PA/MRI and PTT effects for multimodal imaging-guided cancer treatment. In contrast, MICN-PEG is gradually collapsed in normal tissues, resulting in the significant improvement of imaging accuracy and treatment specificity. MICN-PEG is gradually cleared after administration, minimizing concerns about the long-term toxicity.

Oral Cancer Theranostic Application of FeAu Bimetallic Nanoparticles Conjugated with MMP-1 Antibody

Metastatic oral squamous cell carcinoma (SCC) displays a poor disease prognosis with a 5-year survival rate of 39%. Chemotherapy has emerged as the mainstream treatment against small clusters of cancer cells but poses more risks than benefits for metastatic cells due to the non-specificity and cytotoxicity. To overcome these obstacles, we conjugated antibodies specific for matrix metalloproteinase-1 (MMP-1), a prognostic biomarker of SCC, to iron–gold bimetallic nanoparticles (FeAu NPs) and explored the capability of this complex to target and limit SSC cell growth via magnetic field-induced hyperthermia. Our results showed that 4.32 ± 0.79 nm sized FeAu NPs were superparamagnetic in nature with a saturation magnetization (Ms) of 5.8 emu/g and elevated the media temperature to 45 °C, confirming the prospect to deliver hyperthermia. Furthermore, conjugation with MMP-1 antibodies resulted in a 3.07-fold higher uptake in HSC-3 (human tongue squamous cell carcinoma) cells as compared to L929 (fibroblast) cells, which translated to a 5-fold decrease in cell viability, confirming SCC targeting. Finally, upon magnetic stimulation, MMP-1-FeAu NPs conjugate triggered 89% HSC-3 cellular death, confirming the efficacy of antibody-conjugated nanoparticles in limiting SCC growth. The synergistic effect of biomarker-specific antibodies and magnetic nanoparticle-induced hyperthermia may open new doors towards SCC targeting for improved disease prognosis.

Natural Carbon Nanodots: Toxicity Assessment and Theranostic Biological Application

This review outlines the methods for preparing carbon dots (CDs) from various natural resources to select the process to produce CDs with the best biological application efficacy. The oxidative activity of CDs mainly involves photo-induced cell damage and the destruction of biofilm matrices through the production of reactive oxygen species (ROS), thereby causing cell auto-apoptosis. Recent research has found that CDs derived from organic carbon sources can treat cancer cells as effectively as conventional drugs without causing damage to normal cells. CDs obtained by heating a natural carbon source inherit properties similar to the carbon source from which they are derived. Importantly, these characteristics can be exploited to perform non-invasive targeted therapy on human cancers, avoiding the harm caused to the human body by conventional treatments. CDs are attractive for large-scale clinical applications. Water, herbs, plants, and probiotics are ideal carbon-containing sources that can be used to synthesize therapeutic and diagnostic CDs that have become the focus of attention due to their excellent light stability, fluorescence, good biocompatibility, and low toxicity. They can be applied as biosensors, bioimaging, diagnosis, and treatment applications. These advantages make CDs attractive for large-scale clinical application, providing new technologies and methods for disease occurrence, diagnosis, and treatment research.

Recent Progress in Lipid Nanoparticles for Cancer Theranostics: Opportunity and Challenges

Cancer is one of the major leading causes of mortality in the world. The implication of nanotherapeutics in cancer has garnered splendid attention owing to their capability to efficiently address various difficulties associated with conventional drug delivery systems such as non-specific biodistribution, poor efficacy, and the possibility of occurrence of multi-drug resistance. Amongst a plethora of nanocarriers for drugs, this review emphasized lipidic nanocarrier systems for delivering anticancer therapeutics because of their biocompatibility, safety, high drug loading and capability to simultaneously carrying imaging agent and ligands as well. Furthermore, to date, the lack of interaction between diagnosis and treatment has hampered the efforts of the nanotherapeutic approach alone to deal with cancer effectively. Therefore, a novel paradigm with concomitant imaging (with contrasting agents), targeting (with biomarkers), and anticancer agent being delivered in one lipidic nanocarrier system (as cancer theranostics) seems to be very promising in overcoming various hurdles in effective cancer treatment. The major obstacles that are supposed to be addressed by employing lipidic theranostic nanomedicine include nanomedicine reach to tumor cells, drug internalization in cancer cells for therapeutic intervention, off-site drug distribution, and uptake via the host immune system. A comprehensive account of recent research updates in the field of lipidic nanocarrier loaded with therapeutic and diagnostic agents is covered in the present article. Nevertheless, there are notable hurdles in the clinical translation of the lipidic theranostic nanomedicines, which are also highlighted in the present review along with plausible countermeasures.

Recent progress in drug delivery and cancer theranostic built from metal-organic framework

With the improvement of living standards, cancer has become a great challenge around the world during last decades, meanwhile, abundant nanomaterials have been developed as drug delivery system (DDS) or cancer theranostic agents (CTAs) with their outstanding properties. However, low multifunctional efficiency and time-consuming synthesis limit their further applications. Nowadays, green chemistry, in particular, the concept of atom economy, has defined new criteria for the simplicity and efficient production of biomaterials for nanomedicine, which not only owns the property of spatio-temporal precision imaging, but also possess the ability to treat cancer. Interestingly, metal-organic framework (MOF) is an excellent example to meet the requirements behind this concept and has great potential for next-generation nanomedicine. In this review, we summarize our recent researches and inspiring progresses in designing DDS and CTA built from MOF, aiming to show the simplicity, control, and versatility, and provide views on the development of MOF-based nanomedicine in the future.

Finding the perfect match between nanoparticles and microfluidics to respond to cancer challenges

The clinical translation of new cancer theranostic has been delayed by inherent cancer's heterogeneity. Additionally, this delay has been enhanced by the lack of an appropriate in vitro model, capable to produce accurate data. Nanoparticles and microfluidic devices have been used to obtain new and more efficient strategies to tackle cancer challenges. On one hand, nanoparticles-based therapeutics can be modified to target specific cells, and/or molecules, and/or modified with drugs, releasing them over time. On the other hand, microfluidic devices allow the exhibition of physiologically complex systems, incorporation of controlled flow, and control of the chemical environment. Herein, we review the use of nanoparticles and microfluidic devices to address different cancer challenges, such as detection of CTCs and biomarkers, point-of-care devices for early diagnosis and improvement of therapies. The future perspectives of cancer challenges are also addressed herein.

Clearable Theranostic Platform with a pH-Independent Chemodynamic Therapy Enhancement Strategy for Synergetic Photothermal Tumor Therapy

Chemodynamic therapy (CDT) is an emerging field, which utilizes intratumoral iron-mediated Fenton chemistry for cancer therapy. However, the slightly acidic tumor environment is improper for the classical Fenton reaction, which is generally energetic in a narrow pH range (e.g., pH = 3-4). Herein, a kind of ultrasmall bovine serum albumin (BSA)-modified chalcopyrite nanoparticles (BSA-CuFeS₂ NPs) was synthesized via a facile aqueous biomineralization strategy, which shows high dispersity and biocompatibility. Interestingly, the obtained BSA-CuFeS₂ shows a pH-independent Fenton-like reaction, which could exert Fenton-like activity to efficiently generate ^•OH under a weak acidic tumor environment. Combined with the extraordinarily high photothermal conversion (38.8%), BSA-CuFeS₂ shows the synergistic function of high photothermal therapy (PTT) and enhanced CDT, that is, PTT/CDT. Importantly, such ultrasmall BSA-CuFeS₂ NPs measuring around 4.9 nm can be quickly cleared out of the body through kidneys and liver, thus effectively avoiding long-term toxicity and systemic toxicity. Moreover, BSA-CuFeS₂ NPs can act as an efficient T₂-weighted magnetic resonance imaging (MRI) contrast agent to guide tumor ablation in vivo. This work offers a universal approach to boost production ^•OH by a pH-independent Fenton-like reaction strategy and achieves MRI-guided synergistic enhanced photothermal-CDT for highly efficient tumor treatment.

Small Molecule Fluorescent Probes for G- Quadruplex Visualization as Potential Cancer Theranostic Agents

G-quadruplexes have gained prominence over the past two decades for their role in gene regulation, control of anti-tumour activity and ageing. The physiological relevance and significance of these non-canonical structures in the context of cancer has been reviewed several times. Putative roles of G-quadruplexes in cancer prognosis and pathogenesis have spurred the search for small molecule ligands that are capable of binding and modulating the effect of such structures. On a related theme, small molecule fluorescent probes have emerged that are capable of selective recognition of G-quadruplex structures. These have opened up the possibility of direct visualization and tracking of such structures. In this review we outline recent developments on G-quadruplex specific small molecule fluorescent probes for visualizing G-quadruplexes. The molecules represent a variety of structural scaffolds, mechanism of quadruplex-recognition and fluorescence signal transduction. Quadruplex selectivity and in vivo imaging potential of these molecules places them uniquely as quadruplex-theranostic agents in the predominantly cancer therapeutic context of quadruplex-selective ligands.

Nucleic acid aptamer-guided cancer therapeutics and diagnostics: the next generation of cancer medicine

Conventional anticancer therapies, such as chemo- and/or radio-therapy are often unable to completely eradicate cancers due to abnormal tumor microenvironment, as well as increased drug/radiation resistance. More effective therapeutic strategies for overcoming these obstacles are urgently in demand. Aptamers, as chemical antibodies that bind to targets with high affinity and specificity, are a promising new and novel agent for both cancer diagnostic and therapeutic applications. Aptamer-based cancer cell targeting facilitates the development of active targeting in which aptamer-mediated drug delivery could provide promising anticancer outcomes. This review is to update the current progress of aptamer-based cancer diagnosis and aptamer-mediated active targeting for cancer therapy in vivo, exploring the potential of this novel form of targeted cancer therapy.