Recent Advancements in Ultrasound Contrast Agents Based on Nanomaterials for Imaging.

Ultrasound (US) is a type of mechanical wave that is capable of transmitting energy through biological tissues. By utilization of various frequencies and intensities, it can elicit specific biological effects. US imaging (USI) technology has been continuously developed with the advantages of safety and the absence of radiation.

Thermal-Responsive Antibacterial Hydrogel with Photothermal Therapy and Improving Wound Microenvironment for Promote Healing.

Skin damage is one of the most prevalent human injuries, which affects the health of human beings. However, skin damage is often accompanied by bacterial infection and wound microenvironment changes, causing damage to normal cells and inhibiting wound healing. Herein, we designed a thermal-responsive antibacterial hydrogel (GAG hydrogel) loaded with catalase (CAT)-like Au@Pt@MgSiO nanoparticles (APM NPs) and gentamicin (GM) to promote wound healing.

Recent theranostic applications of hydrogen peroxide-responsive nanomaterials for multiple diseases.

It is well established that hydrogen peroxide (HO) is associated with the initiation and progression of many diseases. With the rapid development of nanotechnology, the diagnosis and treatment of those diseases could be realized through a variety of HO-responsive nanomaterials. In order to broaden the application prospects of HO-responsive nanomaterials and promote their development, understanding and summarizing the design and application fields of such materials has attracted much attention.

Simultaneous Fe/Fe imaging shows Fe over Fe enrichment in Alzheimer's disease mouse brain.

Visualizing redox-active metal ions, such as Fe and Fe ions, are essential for understanding their roles in biological processes and human diseases. Despite the development of imaging probes and techniques, imaging both Fe and Fe simultaneously in living cells with high selectivity and sensitivity has not been reported. Here, we selected and developed DNAzyme-based fluorescent turn-on sensors that are selective for either Fe or Fe, revealing a decreased Fe/Fe ratio during ferroptosis and an increased Fe/Fe ratio in Alzheimer's disease mouse brain.

Aptamer-Based Probes for Cancer Diagnostics and Treatment.

Aptamers are single-stranded DNA or RNA oligomers that have the ability to generate unique and diverse tertiary structures that bind to cognate molecules with high specificity. In recent years, aptamer researches have witnessed a huge surge, owing to its unique properties, such as high specificity and binding affinity, low immunogenicity and toxicity, and simplicity of synthesis with negligible batch-to-batch variation. Aptamers may bind to targets, such as various cancer biomarkers, making them applicable for a wide range of cancer diagnosis and treatment.

Monitoring leaching of Cd from cadmium-based quantum dots by an Cd aptamer fluorescence sensor.

Quantum Dots (QDs) have been demonstrated with outstanding optical properties and thus been widely used in many biological and biomedical studies. However, previous studies have shown that QDs can cause cell toxicity, mainly attributable to the leached Cd. Therefore, identifying the leaching kinetics is very important to understand QD biosafety and cytotoxicity.

DNAzyme-Based Lithium-Selective Imaging Reveals Higher Lithium Accumulation in Bipolar Disorder Patient-Derived Neurons.

Lithium has been a drug for bipolar disorders (BD) for over 70 years; however, its usage has been limited by its narrow therapeutic window (between 0.6 and 1.2 mM).

Recent progress in developing fluorescent probes for imaging cell metabolites.

Cellular metabolites play a crucial role in promoting and regulating cellular activities, but it has been difficult to monitor these cellular metabolites in living cells and in real time. Over the past decades, iterative development and improvements of fluorescent probes have been made, resulting in the effective monitoring of metabolites. In this review, we highlight recent progress in the use of fluorescent probes for tracking some key metabolites, such as adenosine triphosphate, cyclic adenosine monophosphate, cyclic guanosine 5'-monophosphate, Nicotinamide adenine dinucleotide (NADH), reactive oxygen species, sugar, carbon monoxide, and nitric oxide for both whole cell and subcellular imaging.

DNAzyme-Mediated Genetically Encoded Sensors for Ratiometric Imaging of Metal Ions in Living Cells.

Genetically encoded fluorescent proteins (FPs) have been used for metal ion detection. However, their applications are restricted to a limited number of metal ions owing to the lack of available metal-binding proteins or peptides that can be fused to FPs and the difficulty in transforming the binding of metal ions into a change of fluorescent signal. We report herein the use of Mg-specific 10-23 or Zn-specific 8-17 RNA-cleaving DNAzymes to regulate the expression of FPs as a new class of ratiometric fluorescent sensors for metal ions.

A photo-regulated aptamer sensor for spatiotemporally controlled monitoring of ATP in the mitochondria of living cells.

Fluorescent aptamer sensors have shown enormous potential for intracellular imaging of small molecule metabolites. Since metabolites distribute differently at different subcellular locations and their concentrations and locations fluctuate with time, methods are needed for spatiotemporally controlled monitoring of these metabolites. Built upon previous success in temporal control of aptamer-based sensors, we herein report an aptamer sensor containing a photocleavable linker and using DQAsomes to target mitochondria for spatiotemporally controlled monitoring of ATP in the mitochondria of living cells.

DNAzyme-Mediated Genetically Encoded Sensors for Ratiometric Imaging of Metal Ions in Living Cells.

Genetically encoded fluorescent proteins (FPs) have been used for metal ion detection. However, their applications are restricted to a limited number of metal ions owing to the lack of available metal-binding proteins or peptides that can be fused to FPs and the difficulty in transforming the binding of metal ions into a change of fluorescent signal. We report herein the use of Mg -specific 10-23 or Zn -specific 8-17 RNA-cleaving DNAzymes to regulate the expression of FPs as a new class of ratiometric fluorescent sensors for metal ions.

Self-Assembled saRNA Delivery System Based on Rolling Circle Transcription for Aptamer-Targeting Cancer Therapy.

With the capacity of gene promotion, RNA activation (RNAa) has been supposed to be a powerful technique in the field of biomedicine, especially in an antitumor aspect. However, one of the pressing challenges for clinical application is how to efficiently deliver therapeutic probes to cancer. Herein, we synthesized a carrier through rolling circle transcription (RCT) to deliver p21 saRNA with high loading rate and targeting capacity.

Aptamer-integrated α-Gal liposomes as bispecific agents to trigger immune response for killing tumor cells.

A novel bispecific α-Gal liposome was constructed by self-assembling AS1411 aptamers into the α-Gal containing liposomes. The α-Gal liposomes were prepared using cell membranes of red blood cells from rabbit, which are composed of cholesterol, phospholipids, and α-Gal glycolipids. AS1411 is a DNA aptamer with high specificity and affinity for nucleolin and could integrate into liposomes by the modification of cholesterol.

Folic acid-modified fluorescent dye-protein nanoparticles for the targeted tumor cell imaging.

Serum albumin has a wide range of applications in biochemical experiments and pharmaceutical field. We found that a cyanine dye, dimethylindole red (Dir), could selectively interact with bovine serum albumin (BSA). Dir exhibited very weak red fluorescence, while the fluorescence intensity at 630 nm was enhanced up to 130-fold upon noncovalently interacting with 30 µM BSA.

Self-assembled RNAi nanoflowers via rolling circle transcription for aptamer-targeted siRNA delivery.

To deliver siRNA efficiently, prevailing conventional lipid or polymer encapsulation often needs multi-step compounding methods, which may inevitably introduce cationic or other components and may lead to cytotoxicity or an immune response. Herein, we present a novel enzymatic synthetic approach to produce tumor-targetable RNAi nanoflowers. The RNAi nanoflowers are mainly composed of multiple tandem copies of siRNA precursors by rolling circle transcription (RCT), and produce large amounts of siRNA to silence Bcl-2 gene expression after cellular uptake, which can overcome the problem of low loading capacity.

In vitro selection of DNA aptamers against renal cell carcinoma using living cell-SELEX.

Renal cell carcinoma (RCC) is the most common form of kidney cancer with poor prognosis. Early diagnosis of RCC would significantly improve patient prognosis and quality of life. In this work, we developed new aptamer probes for RCC by using cell-SELEX (systematic evolution of ligands by exponential enrichment) only after 12 rounds of selection, in which a clear cell renal cell carcinoma (ccRCC) cell line 786-O was used as target cell, and embryonic kidney cell line 293T as negative control cell.

GdO and GH combined with red blood cells to improve the sensitivity of contrast agents for cancer targeting MR imaging.

Herein, we fabricated efficient MR imaging probes by incorporating gadolinium oxide nanoparticles (GdO) and gadolinium hybrid nanoparticles (GH) within RBCs. The GdO and GH encapsulated in the RBCs exhibited high relaxation rates and revealed high sensitivity for T MR imaging.

Label-free DNA-based biosensors using structure-selective light-up dyes.

Label-free biosensors (LFBs) have demonstrated a great potential in cost-effective applications, and most of the DNA-based LFBs are based on the principle of binding-induced structural transformation. This review is a collection of the latest reported studies, which have employed structure-selective nucleic acid dyes for the development of DNA-based LFBs. The collections in this review have been structured based on the selective binding of dyes towards specific DNA conformations, including single-stranded DNA, double-stranded DNA, triplex DNA, i-motifs and G-quadruplexes.

DNA Triplexes-Guided Assembly of G-Quadruplexes for Constructing Label-free Fluorescent Logic Gates.

Assembly of G-quadruplexes guided by DNA triplexes in a controlled manner is achieved for the first time. The folding of triplex sequences in acidic conditions brings two separated guanine-rich sequences together and subsequently a G-quadruplex structure is formed in the presence of K(+) . Based on this novel platform, label-free fluorescent logic gates, such as AND, INHIBIT, and NOR, are constructed with ions as input and the fluorescence of a G-quadruplex-specific fluorescent probe NMM as output.

Functional Hyperbranched Polylysine as Potential Contrast Agent Probes for Magnetic Resonance Imaging.

Researchers have never stopped questing contrast agents with high resolution and safety to overcome the drawbacks of small-molecule contrast agents in clinic. Herein, we reported the synthesis of gadolinium-based hyperbranched polylysine (HBPLL-DTPA-Gd), which was prepared by thermal polymerization of l-lysine via one-step polycondensation. After conjugating with folic acid, its potential application as MRI contrast agent was then evaluated.

DNA sequence-dependent fluorescence of doxorubicin for turn-on detection of biothiols in human serum.

Doxorubicin (Dox) is a DNA-targeting anthracycline antibiotic active against a wide spectrum of cancers. The interaction between Dox and double-stranded DNA (dsDNA) was used to load Dox using DNA duplexes as carriers. More importantly, the interesting DNA sequence-dependent fluorescence response of Dox could be exploited in the design of efficient Dox release systems and efficient fluorescence sensors.

Berberine as a novel light-up i-motif fluorescence ligand and its application in designing molecular logic systems.

Berberine, a new light-up fluorescence ligand, for i-motif structures has been reported. This interaction enabled the development of label-free DNA-based logic gates in response to input signals.

A Cellular Compatible Chitosan Nanoparticle Surface for Isolation and In Situ Culture of Rare Number CTCs.

Circulating tumor cell (CTC) isolation has attracted a great deal of research interest in recent years. However, there are still some challenges, including purity as well as viability of the captured CTCs, resulting from nanoscale structures and inorganic nanomaterials. Here, a chitosan nanoparticle surface is first fabricated by electrospray to provide a cellular compatible interface.

Turn-on and label-free fluorescence detection of lead ions based on target-induced G-quadruplex formation.

Using a guanine-rich sequence (AGRO100) and N-methyl mesoporphyrin IX (NMM), a turn-on and label-free fluorescent Pb(2+) sensor with high sensitivity and low background fluorescence was presented as a representative of five turn-on sensing systems.