Exosomal microRNAs are essential in intercellular communications and disease progression, yet it remains challenging to quantify the expression level due to their small size and low abundance in blood. Here, we report a “sandwich” electrochemical exosomal microRNA sensor (SEEmiR) to detect target microRNA with high sensitivity and specificity. In SEEmiR, neutrally charged peptide nucleic acid (PNA) enables kinetically favorable hybridization with the microRNA target relative to negatively charged DNA, particularly in a short sequence (10 nt). More importantly, this property allows PNA to cooperate with a spherical nucleic acid (SNA) nanoprobe that heavily loads with oligonucleotide-adsorbed electroactive tags to enhance detection sensitivity and specificity. Such a PNA–microRNA–SNA sandwich construct is able to minimize the background noise via PNA, thereby maximizing the SNA-mediated signal amplification in electrostatic adsorption-based SEEmiR. The synergy between PNA and SNA makes the SEEmiR sensor able to achieve a broad dynamic range (from 100 aM to 1 nM) with a detection limit down to 49 aM (2 orders of magnitude lower than that without SNA) and capable of distinguishing a single-base mismatch. This ultrasensitive sensor provides label-free and enzyme-independent microRNA detection in cell lysates, unpurified tumor exosomal lysates, cancer patients’ blood, and accurately differentiates the patients with breast cancer from the healthy ones, suggesting its potential as a promising tool in cancer diagnostics.
Exosome-associated liquid biopsies are hampered by challenges in the exosomal quantification and phenotyping. Here, we present a bioinspired exosome-activated DNA molecular machine (ExoADM) with multivalent cyclic amplification that enables highly sensitive detection and phenotyping of circulating exosomes. ExoADM harbors two (an exposed and a hidden) DNA toehold domains that actuate sequential branch migration and multivalent recycling in response to exosomal surface markers. Importantly, this self-powered ExoADM achieves a high sensitivity (33 particles/μL) and is compatible with another DNA nanomachine targeting different exosomal surface markers for dual-color phenotyping. Using this strategy, we can simultaneously track the dynamic changes of ExoPD-L1 and ExoCD63 expression induced by signaling molecules. Further, we found that their expression levels on circulating exosomes could well differentiate cancer patients from the normal individuals. More importantly, ExoPD-L1 levels could reflect the efficacy of different treatments and guide anti-PD-1 immunotherapy, suggesting the potential of ExoPD-L1 in clinical diagnosis and targeted therapy monitoring.
Photodynamic therapy (PDT) is a non-invasive treatment modality against a range of cancers and nonmalignant diseases, however one must be aware of the risk of causing phototoxic reactions after treatment. We herein report a bioinspired design of next-generation photosensitizers (PSs) that not only effectively produce ROS but undergo fast metabolism after treatment to overcome undesirable side effects. We constructed a series of β-pyrrolic ringopening seco-chlorins, termed beidaphyrin (BP), beidapholactone (BPL), and their zinc(II) derivatives (ZnBP and ZnBPL), featuring intense near-infrared absorption and effective O 2 photosensitization. Irradiation of ZnBPL led to a non-cytotoxic, metabolizable beidaphodiacetamide (ZnBPD) via in situ generated O 2 *À but not 1 O 2 , as revealed by mechanistic studies including time-resolved absorption, kinetics, and isotope labeling. Furthermore, water-soluble ZnBPL showed an effective therapeutic outcome, fast metabolism, and negligible phototoxic reactions.
Gallium, the group 13 metal, has been found to be potentially useful in fighting against cancers since last century. The trivalent Ga(III) shares most chemical properties except redox activity with Fe(III), so that it acts as a competitive inhibitor of Fe(III) in vitro and in vivo, which contributes to its antineoplastic activity. As an Fe(III) mimic, Ga(III) can be uptaken into cells through transferrin and be stored in ferritin. Furthermore, it disrupts Fe‐dependent processes, for example, by inhibiting the activity of ribonucleotide reductase and Fe‐containing proteins in the respiratory chain. To solve the problems of complex Ga(III) speciation in the circulatory system, a large number of ligands were applied to form Ga(III) complexes, supplying multiple functions. In this review, we summarized the anticancer mechanisms of Ga(III) and introduce numerous Ga(III) complexes with great antineoplastic potential.
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