DNA Polymer Nanoparticles Programmed via Supersandwich Hybridization for Imaging and Therapy of Cancer Cells

Recent advances in photodynamic therapy combined with chemotherapy for cervical cancer: a systematic review

INTRODUCTION

Despite the evidence that photodynamic therapy (PDT) associated with chemotherapy presents great potential to overcome the limitations of monotherapy, little is known about the current status of this combination against cervical cancer. This systematic review aimed to address the currently available advances in combining PDT and chemotherapy in different research models and clinical trials of cervical cancer.

METHODS

We conducted a systematic review based on PRISMA Statement and Open Science Framework review protocol using PubMed, Web of Science, Embase, Scopus, LILACS, and Cochrane databases. We selected original articles focusing on 'Uterine Cervical Neoplasms' and 'Photochemotherapy and Chemotherapy' published in the last 10 years. The risk of bias in the studies was assessed using the CONSORT and SYRCLE tools.

RESULTS

Twenty-three original articles were included, focusing on HeLa cells, derived from endocervical adenocarcinoma and on combinations of several chemotherapeutics. Most of the combinations used modern drug delivery systems for improved simultaneous delivery and presented promising results with increased cytotoxicity compared to monotherapy.

CONCLUSION

Despite the scarcity of animal studies and the absence of clinical studies, the combination of chemotherapy with PDT presents a potential option for cervical cancer therapy requiring additional studies.

OSF REGISTRATION

https://doi.org/10.17605/OSF.IO/WPHN5 [Figure: see text].

Recent advances in functional nucleic acid decorated nanomaterials for cancer imaging and therapy

Nanomaterials possess unusual physicochemical properties including unique optical, magnetic, electronic properties, and large surface-to-volume ratio. However, nanomaterials face some challenges when they were applied in the field of biomedicine. For example, some nanomaterials suffer from the limitations such as poor selectivity and biocompatibility, low stability, and solubility. To address the above-mentioned obstacles, functional nucleic acid has been widely served as a powerful and versatile ligand for modifying nanomaterials because of their unique characteristics, such as ease of modification, excellent biocompatibility, high stability, predictable intermolecular interaction and recognition ability. The functionally integrating functional nucleic acid with nanomaterials has produced various kinds of nanocomposites and recent advances in applications of functional nucleic acid decorated nanomaterials for cancer imaging and therapy were summarized in this review. Further, we offer an insight into the future challenges and perspectives of functional nucleic acid decorated nanomaterials.

Nucleolin-Targeting AS1411 Aptamer-Conjugated Nanospheres for Targeted Treatment of Glioblastoma

Post-operative chemotherapy is still required for the treatment of glioblastoma (GBM), for which nanocarrier-based drug delivery has been identified as one of the most effective methods. However, the blood-brain barrier (BBB) and non-specific delivery to non-tumor tissues can significantly limit drug accumulation in tumor tissues and cause damage to nearby normal tissues. This study describes a targeted cancer therapy approach that uses AS1411 aptamer-conjugated nanospheres (100-300 nm in size) loaded with doxorubicin (Dox) to selectively identify tumor cells overexpressing nucleolin (NCL) proteins. The study demonstrates that the active target model, which employs aptamer-mediated drug delivery, is more effective than non-specific enhanced permeability and maintenance (EPR)-mediated delivery and passive drug delivery in improving drug penetration and maintenance in tumor cells. Additionally, the study reveals the potential for anti-cancer effects through 3D spheroidal and in vivo GBM xenograft models. The DNA-protein hybrid nanospheres utilized in this study offer numerous benefits, such as efficient synthesis, structural stability, high drug loading, dye labeling, biocompatibility, and biodegradability. When combined with nanospheres, the 1411 aptamer has been shown to be an effective drug delivery carrier allowing for the precise targeting of tumors. This combination has the potential to produce anti-tumor effects in the active targeted therapy of GBM.

Spherical nucleic acids: emerging amplifiers for therapeutic nanoplatforms

Gene therapy is a revolutionary treatment approach in the 21st century, offering significant potential for disease prevention and treatment. However, the efficacy of gene delivery is often compromised by the inherent challenges of gene properties and vector-related defects. It is crucial to explore ways to enhance the curative effect of gene drugs and achieve safer, more widespread, and more efficient utilization, which represents a significant challenge in amplification gene therapy advancements. Spherical nucleic acids (SNAs), with their unique physicochemical properties, are considered an innovative solution for scalable gene therapy. This review aims to comprehensively explore the amplifying contributions of SNAs in gene therapy and emphasize the contribution of SNAs to the amplification effect of gene therapy from the aspects of structure, application, and recent clinical translation - an aspect that has been rarely reported or explored thus far. We begin by elucidating the fundamental characteristics and scaling-up properties of SNAs that distinguish them from traditional linear nucleic acids, followed by an analysis of combined therapy treatment strategies, theranostics, and clinical translation amplified by SNAs. We conclude by discussing the challenges of SNAs and provide a prospect on the amplification characteristics. This review seeks to update the current understanding of the use of SNAs in gene therapy amplification and promote further research into their clinical translation and amplification of gene therapy.

Robust noncovalent spherical nucleic acid enzymes (SNAzymes) for ultrasensitive unamplified electrochemiluminescence detection of endogenous myocardial MicroRNAs

Here we develop robust noncovalent spherical nucleic acid enzymes (SNAzymes) for direct electrochemiluminescence (ECL) detection of acute myocardial infarction (AMI) related endogenous microRNAs in both circulating blood and cardiomyocytes, which circumvents the need for time-consuming signal amplification widely used in previous counterparts. It mainly relies on the super peroxidase-like activity of the designed noncovalent SNAzymes, promoted by a few nucleotides flanking on the 3'-terminals of common parallel G-quadruplexes (G4). For this reason, an unmodified G4 with an A5T30 head is well chosen and then attached robustly onto bare AuNPs via microwave-assisted heating-drying. A probe strand is meanwhile attached onto SNAzymes, enabling the target microRNA-triggered formation of a Y-shaped junction together with a capture strand tethered to a DNA tetrahedron on the electrode surface. The utilization of this tetrahedral nanoscaffold favors the ECL readout and thereby contributes to high sensitivity of the sensing platform. In this way, an AMI-related microRNA, miR-499, can be probed in a wide linear range, with a detection limit of 33 aM and high selectivity over other analogues. Furthermore, our developed sensing platform is employed to analyze endogenous miR-499 in AMI patients' blood, revealing an apparently higher level than the mean value of the healthy. What it means to patients, heart injury, is elucidated by comparing the miR-499 levels of cardiomyocytes and other tissue cells, with endogenous miR-16 as an intrinsic reference.

Spherical nucleic acids-based nanoplatforms for tumor precision medicine and immunotherapy

Precise diagnosis and treatment of tumors currently still face considerable challenges due to the development of highly degreed heterogeneity in the dynamic evolution of tumors. With the rapid development of genomics, personalized diagnosis and treatment using specific genes may be a robust strategy to break through the bottleneck of traditional tumor treatment. Nevertheless, efficient in vivo gene delivery has been frequently hampered by the inherent defects of vectors and various biological barriers. Encouragingly, spherical nucleic acids (SNAs) with good modularity and programmability are excellent candidates capable of addressing traditional gene transfer-associated issues, which enables SNAs a precision nanoplatform with great potential for diverse biomedical applications. In this regard, there have been detailed reviews of SNA in drug delivery, gene regulation, and dermatology treatment. Still, to the best of our knowledge, there is no published systematic review summarizing the use of SNAs in oncology precision medicine and immunotherapy, which are considered new guidelines for oncology treatment. To this end, we summarized the notable advances in SNAs-based precision therapy and immunotherapy for tumors following a classification standard of different types of precise spatiotemporal control on active species by SNAs. Specifically, we focus on the structural diversity and programmability of SNAs. Finally, the challenges and possible solutions were discussed in the concluding remarks. This review will promote the rational design and development of SNAs for tumor-precise medicine and immunotherapy.

Research progress in nucleus-targeted tumor therapy

The nucleus is considered the most important organelle in the cell as it plays a central role in controlling cell reproduction, metabolism, and the cell cycle. The successful delivery of drugs into the nucleus can achieve excellent therapeutic effects, which reveals the potential of nucleus-targeted therapy in precision medicine. However, the transportation of therapeutics into the nucleus remains a significant challenge due to various biological barriers. Herein, we summarize the recent progress in the nucleus-targeted drug delivery system (NDDS). The structures of the nucleus and nuclear envelope are first described in order to understand the mechanisms by which drugs cross the nuclear envelope. Then, various drug delivery strategies based on the mechanisms and their applications are discussed. Finally, the challenges and solutions in the field of nucleus-targeted drug delivery are raised for developing a more efficient NDDS and promoting its clinical transformation.

High-Throughput Effect-Directed Monitoring Platform for Specific Toxicity Quantification of Unknown Waters: Lead-Caused Cell Damage as a Model Using a DNA Hybrid Chain-Reaction-Induced AuNPs@aptamer Self-Assembly Assay

A high-throughput cell-based monitoring platform was fabricated to rapidly measure the specific toxicity of unknown waters, based on AuNPs@aptamer fluorescence bioassays. The aptamer is employed in the platform for capturing the toxicity indicator, wherein hybrid chain-reaction (HCR)-induced DNA functional gold nanoparticle (AuNPs) self-assembly was carried out for signal amplification, which is essential for sensitively measuring the sub-lethal effects caused by target compounds. Moreover, the excellent stability given by the synthesized DNA nanostructure provides mild conditions for the aptamer thus used to bind the analyte. Herein, ATP was treated as a toxicity indicator and verified using lead-caused cell damage as a model. Under optimized conditions, excellent performance for water sample measurement was observed, yielding satisfactory accuracy (recovery rate: 82.69-114.20%; CV, 2.57%-4.65%) and sensitivity (LOD, 0.26 µM) without sample pretreatment other than filtration, indicating the method's simplicity, high efficiency, and reliability. Most importantly, this bioassay could be used as a universal platform to encourage its application in the rapid quantification of specific toxicity in varied sources of samples, ranging from drinking water to highly contaminated wastewater.

Stimuli-Responsive Self-Degradable DNA Hydrogels: Design, Synthesis, and Applications

DNA hydrogels play an increasingly important role in biomedicine and bioanalysis applications. Due to their high programmability, multifunctionality and biocompatibility, they are often used as effective carriers for packing drugs, cells, or other bioactive cargoes in vitro and in vivo. However, the stability of the DNA hydrogels prevents their in-demand rapid release of cargoes to achieve a full therapeutic effect in time. For bioanalysis, the generation of signals sometimes needs the DNA hydrogel to be rapidly degraded when sensing target molecules. To meet these requirements, stimulus-responsive DNA hydrogels are designed. By responding to different stimuli, self-degradable DNA hydrogels can switch from gel to solution for quantitative bioanalysis and precision cargo delivery. This review summarizes the recently developed innovative methods for designing stimuli-responsive self-degradable DNA hydrogels and showed their applications in the bioanalysis and biomedicines fields. Challenges, as well as prospects, are also discussed.

Self-Assembled ATP-Responsive DNA Nanohydrogel for Specifically Activated Fluorescence Imaging and Chemotherapy in Cancer Cells

Tumor marker-responsive drug delivery systems have been developed for cancer imaging and chemotherapy. However, improving their ability of controlled drug release remains a challenge. In this study, we have developed an adenosine triphosphate (ATP)-responsive DNA nanohydrogel for specifically activated fluorescence imaging and chemotherapy in cancer cells. Acrylamide and acrydite-modified DNAs were polymerized to obtain DNA-grafted polyacrylamide copolymers. Then, the copolymers acted as the backbone of the nanohydrogel and were assembled by base complementation with ATP aptamer linkers to construct an ATP-responsive nanohydrogel. Meanwhile, the chemotherapeutic drug doxorubicin (DOX) was added and loaded into the ATP-responsive nanohydrogel during the assembly process. After endocytosis by cancer cells and response to a high intracellular ATP level, the DOX-loaded nanohydrogel disassembled due to the formation of aptamer/ATP complexes. Subsequently, the released DOX played a role in fluorescence imaging and chemotherapy of cancer cells. Through the ATP-responsive property and satisfying drug delivery capability, this nanohydrogel realized fluorescence imaging and specific cancer cell killing capabilities due to different intracellular ATP levels in normal and cancer cell lines. In summary, this study has provided a novel strategy of constructing a tumor microenvironment-responsive drug delivery system triggered by the tumor markers for tumor intracellular imaging and chemotherapy.

ATP-Triggered Drug Release of Self-Assembled 3D DNA Nanostructures for Fluorescence Imaging and Tumor Therapy

Stimulus-responsive materials are ideal carriers for precisely controlled drug delivery due to their high selectivity. However, the complex physiological environment hinders its development in clinical medicine. Here, we aim to design a self-assembled three-dimensional (3D) DNA nanostructure drug delivery system with adenosine-5'-triphosphate (ATP)-triggered drug release for tumor fluorescence imaging analysis and targeted drug delivery. Dox@3D DNA nanostructures are self-assembled by a simple one-pot annealing reaction and embedded with drugs, which are structurally stable but can be induced using high concentrations of ATP in tumor cells to cleave and release drugs rapidly, facilitating the rapid accumulation of drugs in tumors and exerting therapeutic effects, thus effectively avoiding damage to normal tissues. This work demonstrates that 3D DNA nanostructures can be used as efficient drug nanocarriers with promising applications in tumor therapy.

Construction of nanocarriers based on nucleic acids and their application in nanobiology delivery systems

In recent years, nanocarriers based on nucleic acids (NCNAs) have emerged as powerful and novel nanocarriers that are able to meet the demand for cancer cell-specific targeting. Functional dynamics analysis revealed good biocompatibility, low toxicity, and programmable structures, and their advantages include controllable size and modifiability. The development of novel hybrids has focused on the distinct roles of biosensing, drug and gene delivery, vaccine transport, photosensitization, counteracting drug resistance and functioning as carriers and logic gates. This review is divided into three parts: (1) DNA nanocarriers, (2) RNA nanocarriers, and (3) DNA/RNA hybrid nanocarriers and their biological applications. We also provide perspectives on possible future directions for growth in this field.

Metal-organic frameworks-assisted nonenzymatic cascade amplification multiplexed strategy for sensing acute myocardial infarction related microRNAs

Amplification strategies for multiple microRNAs (miRNAs) detection are pivotal for acute myocardial infarction (AMI). Herein, we rationally developed a metal-organic frameworks-assisted nonenzymatic cascade amplification strategy for simultaneous quantification of three AMI-related miRNAs (miR-21, miR-499 and miR-133a). The fluorescence of the elaborately designed DNA molecular beacons with the respective modification of FAM, TAMRA and Cy5 in the terminal was quenched by a metal-organic framework named Fe-MIL-88. When targets miRNA appeared, they hybridized with the corresponding DNA molecular beacons, and the catalyzed hairpin assembly (CHA) reaction would be triggered, producing "Y" shaped three-branched duplex nanostructure with the targets released, and initiating subsequent another cycle. The "Y" shaped nanostructures could not be adsorbed onto the surface of Fe-MIL-88 due to the weaker affinity between Fe-MIL-88 and "Y" shaped nanostructures. Therefore, the fluorescence of "Y" shaped nanostructures could not be quenched by Fe-MIL-88. In this way, three AMI-related miRNAs were simultaneously detected in the respective ranges of 0.05-30 nM, 0.08-30 nM and 0.1-20 nM with respective limits of detection down to 13, 25 and 40 pM. Furthermore, the method was successfully employed to determine three AMI-related miRNAs in human serum. The strategy offered great opportunity for ultrasensitive detecting multiple AMI-related miRNAs and substantially improving the accuracy of clinical early AMI diagnosis.

Dual aptamer recognition-based G-quadruplex nanowires to selectively analyze cancer-derived exosomes

Cancer-derived exosomes have emerged as a valuable biomarker for cancer diagnosis and prognosis. However, the heterogeneity of exosomes often leads to low selectivity based on the single recognition method. Given this, we have developed a dual-aptamer recognition strategy based on G-quadruplex nanowires for selective analysis of exosomes. In this work, target exosomes were first captured by CD63 aptamers modified on magnetic beads (MBs) and then combined with AS1411 aptamer, which shows high binding affinity to nucleolin when forming stable G-quadruplex structure. Then the free myc monomer can spontaneously assemble into higher order G-wire superstructures on the allosteric AS1411, and resulting enhanced fluorescence signal, which can realize sensitive and specific analysis of the target exosomes. This dual-aptamer recognition-based method is simple and universal for different types of exosomes, which is of great significance for clinical cancer diagnosis.

Selective thermotherapy of tumor by self-regulating photothermal conversion system

One major challenge of photothermal therapy (PTT) is achieving thermal ablation of the tumor without damaging the normal cells and tissues. Here, we designed a self-regulating photothermal conversion system for selective thermotherapy based on self-assembling gold nanoparticles (S-AuNPs) and investigated the selectivity effect using a novel home-made in vitro selective photothermal transformation model and an in vivo skin damaging assessment model. In the in vitro selective photothermal transformation model, laser irradiation selectively increased the temperature of the internal microenvironment (pH 5.5) and resulted in an obvious temperature difference (ΔT ≥ 5 °C) with that of the external environment (pH 7.4). More importantly, in the in vivo skin damaging assessment model, S-AuNPs achieved good tumor inhibition without damaging the normal skin tissue compared with the conventional photothermal material. This work provides not only a novel validation protocol for tumor thermotherapy to achieve the biosafety of specifically killing tumor cells and normal tissue but also an evaluation methodology for other precise therapy for cancers.

A MnO2-coated multivariate porphyrinic metal-organic framework for oxygen self-sufficient chemo-photodynamic synergistic therapy

Lately, chemotherapy and photodynamic therapy (PDT) synergistic therapy has become a promising anti-cancer treatment mean. However, the hypoxia in tumor leads to huge impediments to the oxygen-dependentPDT effects. In this work, a multifunctional nanoplatform (TUDMP) based on a multivariable porphyrin-nMOFs core and a manganese dioxide (MnO₂) shell was prepared for relieving tumor hypoxia and enhancing chemo-photodynamic synergistic therapy performance. The obtained TUDMP nanoplatform could effectively catalyze the hydrolysis of hydrogen peroxide to generate oxygen and also lead to consumption of antioxidant GSH, thereby facilitating the production of cytotoxic reactive oxygen species (ROS) by photosensitizer under laser irradiation. More importantly, the decomposition of the MnO₂ shell would further promote the release of the loaded doxorubicin (DOX), and thus an efficient chemo-PDT synergistic therapy was realized. Both in vitro and in vivo experimental results demonstrated the oxygen self-sufficient multifunctional nanoplatform could exhibit significantly enhanced anticancer efficiencies compared with chemotherapy or PDT alone.

Improving Breast Cancer Treatment Specificity Using Aptamers Obtained by 3D Cell-SELEX

Three-dimensional spheroids of non-malignant MCF10A and malignant SKBR3 breast cells were used for subsequent 3D Cell-SELEX to generate aptamers for specific binding and treatment of breast cancer cells. Using 3D Cell-SELEX combined with Next-Generation Sequencing and bioinformatics, ten abundant aptamer families with specific structures were identified that selectively bind to SKBR3, and not to MCF10A cells. Multivalent aptamer polymers were synthesized by co-polymerization and analyzed for binding performance as well as therapeutic efficacy. Binding performance was determined by confocal fluorescence imaging and revealed specific binding and efficient internalization of aptamer polymers into SKBR3 spheroids. For therapeutic purposes, DNA sequences that intercalate the cytotoxic drug doxorubicin were co-polymerized into the aptamer polymers. Viability tests show that the drug-loaded polymers are specific and effective in killing SKBR3 breast cancer cells. Thus, the 3D-selected aptamers enhanced the specificity of doxorubicin against malignant over non-malignant breast cells. The innovative modular DNA aptamer platform based on 3D Cell SELEX and polymer multivalency holds great promise for diagnostics and treatment of breast cancer.

Rationally Programming Nanomaterials with DNA for Biomedical Applications

DNA is not only a carrier of genetic information, but also a versatile structural tool for the engineering and self-assembling of nanostructures. In this regard, the DNA template has dramatically enhanced the scalability, programmability, and functionality of the self-assembled DNA nanostructures. These capabilities provide opportunities for a wide range of biomedical applications in biosensing, bioimaging, drug delivery, and disease therapy. In this review, the importance and advantages of DNA for programming and fabricating of DNA nanostructures are first highlighted. The recent progress in design and construction of DNA nanostructures are then summarized, including DNA conjugated nanoparticle systems, DNA-based clusters and extended organizations, and DNA origami-templated assemblies. An overview on biomedical applications of the self-assembled DNA nanostructures is provided. Finally, the conclusion and perspectives on the self-assembled DNA nanostructures are presented.

Novel electro self-assembled DNA nanospheres as a drug delivery system for atenolol

We describe new method for preparing DNA nanospheres for a self-assembled atenolol@DNA (core/shell) drug delivery system. In this paper, we propose the electrochemical transformation of an alkaline polyelectrolyte solution of DNA into DNA nanospheres. We successfully electrosynthesized DNA nanospheres that were stable for at least 2 months at 4 °C. UV-visible spectra of the prepared nanospheres revealed a peak ranging from 372 to 392 nm depending on the DNA concentration and from 361 to 398.3 nm depending on the electrospherization time. This result, confirmed with size distribution curves worked out from transmission electron microscopy (TEM) images, showed that increasing electrospherization time (6, 12 and 24 h) induces an increase in the average size of DNA nanospheres (48, 65.5 and 117 nm, respectively). In addition, the average size of DNA nanospheres becomes larger (37.8, 48 and 76.5 nm) with increasing DNA concentration (0.05, 0.1 and 0.2 wt%, respectively). Also, the affinity of DNA chains for the surrounding solvent molecules changed from favorable to bad with concomitant extreme reduction in the zeta potential from -31 mV to -17 mV. Principally, the attractive and hydrophobic interactions tend to compact the DNA chain into a globule, as confirmed by Fourier transform infrared spectroscopy (FTIR) and TEM. To advance possible applications, we successfully electro self-assembled an atenolol@DNA drug delivery system. Our findings showed that electrospherization as a cost-benefit technique could be effectively employed for sustained drug release. This delivery system achieved a high entrapment efficiency of 68.03 ± 2.7% and a moderate drug-loading efficiency of 3.73%. The FTIR spectra verified the absence of any chemical interaction between the drug and the DNA during the electrospherization process. X-ray diffraction analysis indicated noteworthy lessening in atenolol crystallinity. The present findings could aid the effectiveness of electrospherized DNA for use in various other pharmaceutical and biomedical applications.

Hybrid nanoparticle composites applied to photodynamic therapy: strategies and applications

Photodynamic therapy (PDT), as a robust strategy, has long been applied to cancer treatment owing to the meaningful breakthroughs and unique advantages, including ignorable invasiveness and spatio-temporal selectivity. Numerous PDT agents, especially hybrid nanoparticle composite (hybrid)-based sensitizers consisting of an organic polymer and inorganic nanoparticles (NPs), feature the synergetic pros of the components, which have unlocked the additional potentials of PDT. Although reviews relating to the applications of hybrids to PDT have been previously reported, most of them only focus on the designs of smart hybrids integrating multimodal imaging-guided multiple treatment modalities. Traditional PDT treatment has several limitations, such as inadequate PDT agents accumulating in cancer tissues, inferior PDT effect due to the devastating cancer hypoxia environment, relevant systemic toxicity in non-intelligent stimulation response treatment systems, and serious dependence of PDT on external light sources. Many strategies have been developed for overcoming these limitations, including improvement of cancer-homing ability by introducing active targeting groups, remodeling of the cancer hypoxia environment through oxygen regulators, intratumor release of ROS through activatable molecules, and replacement of laser light by X-rays or self-luminescence. This review aims to summarize the most recent advances in designing hybrids for improving the therapeutic efficacy of PDT.

Lysosomal escaped protein nanocarriers for nuclear-targeted siRNA delivery

In the process of drug carrier design, lysosome degradation in cells is often neglected, which makes a considerable number of drugs not play a role. Here, we have constructed a tumor treatment platform (Apn/siRNA/NLS/HA/Apt) with unique lysosomal escape function and excellent cancer treatment effect. Apoferritin (Apn) has attracted more and more attention because of its high uniformity, modifiability, and controllability. Meanwhile, its endogenous nature can avoid the risk of immune response being eliminated. We used aptamer modified iron deficient protein nanocages (Apn) to tightly encapsulate the combination of siRNA and NLS (siRNA/NLS) with influenza virus hemagglutinin (HA peptide). After Apn/siRNA/NLS/HA/Apt was targeted into cells, the acidic environment of lysosome led to the cleavage of Apn nanocages, and the release of siRNA/NLS and HA peptide. HA peptide can destroy lysosome membrane, make siRNA/NLS escape lysosome, and enter the nucleus under the action of NLS, resulting in efficient gene silencing effect. This kind of cancer treatment strategy based on Apn nanocage shows high biocompatibility and unique lysosome escape property, which significantly improves the drug delivery and treatment efficiency. Lysosomal escape protein nanocarriers for nuclear-targeted siRNA delivery.

Aptamer-Functionalized Micro- and Nanocarriers for Controlled Release

Sequence-specific nucleic acids recognizing low-molecular-weight ligands or macromolecules (aptamers) have found growing interest for biomedical applications. The present review article summarizes recent applications of aptamers as stimuli-responsive gating units of drug (or dye)-loaded nano- or microcarriers for controlled and targeted drug release. In the presence of cellular biomarkers, the nano-/microcarriers are unlocked by forming aptamer-ligand complexes. Different aptamer-functinalized nano-/microcarriers are presented, including inorganic nanomaterials, metal-organic framework nanoparticles, and soft materials. The chemistries associated with the preparation of the carriers and the mechanisms to unlock the carriers are discussed. Stimuli-responsive gated drug-loaded micro-/nanocarriers hold great promise as functional sense-and-treat materials for the targeted and selective release of drugs.

Carbon Nanocage/Fe3O4/DNA-Based Magnetically Targeted Intracellular Imaging of Telomerase via Catalyzed Hairpin Assembly and Photodynamic-Photothermal Combination Therapy of Tumor Cells

Human telomerase has been identified as a potential tumor biomarker for early cancer diagnosis and cancer progression monitoring. We construct a novel magnetic targeting carbon nanocage/Fe₃O₄/DNA (CNC/Fe₃O₄/DNA) nanoprobe for intracellular imaging of telomerase via the signal amplification strategy catalyzed hairpin assembly (CHA) and for photodynamic-photothermal therapy of tumor cells. Telomerase primer DNA, trigger DNA, hairpin DNA1 (H1), and hairpin DNA2 (H2) were adsorbed to the surface of CNC/Fe₃O₄ nanoparticles (CNC/Fe₃O₄ NPs), and the fluorescence of (chlorin e6) Ce6 was quenched by CNC/Fe₃O₄ NPs. After entering the living cell through magnetic targeting, the telomerase primer DNA can be extended in the presence of highly activated telomerase, leading to the issue of trigger DNA, which can initiate the CHA cycling process followed by the amplification of the fluorescence intensity. The in vitro detection results justified that the proposed nanoprobe showed good sensitivity and selectivity for telomerase. Confocal microscopy studies indicated that such a nanoprobe can be used to detect the activity of telomerase in living cells and the fluorescence signal was stronger under the guidance of a magnetic field. We successfully employed this nanoprobe to monitor the dynamic activity of telomerase in various types of tumor cells and normal cells and to damage tumor cells by photodynamic-photothermal combination therapy, which evidenced that this is a promising biological method for early cancer diagnosis and tumor cell therapy.

Ligand-Targeted Delivery of Photosensitizers for Cancer Treatment

Photodynamic therapy (PDT) is a promising cancer treatment which involves a photosensitizer (PS), light at a specific wavelength for PS activation and oxygen, which combine to elicit cell death. While the illumination required to activate a PS imparts a certain amount of selectivity to PDT treatments, poor tumor accumulation and cell internalization are still inherent properties of most intravenously administered PSs. As a result, common consequences of PDT include skin photosensitivity. To overcome the mentioned issues, PSs may be tailored to specifically target overexpressed biomarkers of tumors. This active targeting can be achieved by direct conjugation of the PS to a ligand with enhanced affinity for a target overexpressed on cancer cells and/or other cells of the tumor microenvironment. Alternatively, PSs may be incorporated into ligand-targeted nanocarriers, which may also encompass multi-functionalities, including diagnosis and therapy. In this review, we highlight the major advances in active targeting of PSs, either by means of ligand-derived bioconjugates or by exploiting ligand-targeting nanocarriers.

Gold Nanoflares with Computing Function as Smart Diagnostic Automata for Multi-miRNA Patterns in Living Cells

Investigating the multimolecule patterns in living cells is of vital importance for clinical and biomedical studies. Herein, we reported for the first time the engineering of gold nanoflares as smart automata to implement computing-based diagnosis in living mammalian cells. Defining the logic combinations of miR122 and miR21 as the detection patterns, the corresponding OR and AND diagnostic automata were designed. The results showed that they could recognize the correct patterns rapidly and sensitively. The automata could enter cells via self-delivery and have good biocompatibility. They enabled accurate diagnosis on miRNA signatures in different cell lines and differentiation of fluctuations in the same cell line at single cell resolution. Moreover, the automata afforded an innovative diagnostic mode. It simplified the complicated process of detecting, data-collecting, computing, and evaluating. The direct diagnosing result ("1" or "0") was exported according to the embedded computation code. It highlighted the new possibility of using smart automata for intelligent diagnostics and cancer therapy at single cell resolution.

Therapeutic applications of AS1411 aptamer, an update review

Nucleolin or C23, is one of the most abundant non-ribosomal phosphoproteins of nucleolus. However, in several cancers, nucleolin is highly expressed both intracellularly and on the cell surface. So, it is considered as a potential target for the diagnosis and cancer therapy. Targeting nucleolin by compounds such as AS1411 aptamer can reduce tumor cell growth. In this regard, interest has increased in nucleolin as a molecular target for overcoming cancer therapy challenges. This review paper addressed recent progresses in nucleolin targeting by the G-rich AS1411 aptamer in the field of cancer therapy mainly over the past three years.

Cascaded multiple recycling amplifications for aptamer-based ultrasensitive fluorescence detection of protein biomarkers

Highly sensitive detection of molecular biomarkers plays a significant role in diagnosing various types of diseases at the early stage. We demonstrated in this paper an ultrasensitive aptamer-based fluorescence method for detecting mucin 1 (MUC1) in human serum via a cascaded multiple recycling signal amplification strategy. The MUC1 target molecules present in the samples cause structure switching of the hairpin aptamer probes, which initiates three cascaded recycling cycles for the cleavage of the fluorescently quenched signal probes to recover significant fluorescence for highly sensitive detection of MUC1. The developed method has a linear range from 100 fM to 1 nM for MUC1 detection. Besides, owing to the substantial signal amplification by the integrated and cascaded recycling cycles, a low detection limit of 35 fM is achieved with high selectivity. Moreover, the monitoring of trace MUC1 in human serum can also be realized with such a method, indicating its great potential for highly sensitive detection of different disease biomarkers.

Chiral Interaction Is a Decisive Factor To Replace d-DNA with l-DNA Aptamers

Nucleic acid aptamers have been widely used in various fields such as biosensing, DNA chip, and medical diagnosis. However, the high susceptibility of nucleic acids to ubiquitous nucleases reduces the biostability of aptamers and limits their applications in biological contexts. Therefore, improving the biostability of aptamers becomes an urgent need. Herein, we present a simple strategy to resolve this problem by directly replacing the d-DNA-based aptamers with left-handed l-DNA. By testing several reported aptamers against respective targets, we found that our proposed strategy stood up well for nonchiral small molecule targets (e.g., Hemin and cationic porphyrin) and chiral targets whose interactions with aptamers are chirality-independent (e.g., ATP). We also found that the l-DNA aptamers were indeed endowed with greatly improved biostability due to the extraordinary resistance of l-DNA to nuclease digestion. With respect to other small-molecule targets whose interactions with aptamers are chirality-dependent (e.g., kanamycin) and biomacromolecules (e.g., tyrosine kinase-7), however, the proposed strategy was not entirely effective likely due to the participation of the DNA backbone chirality into the target recognition. In spite of this limitation, this strategy indeed paves an easy way to screen highly biostable aptamers important for the applications in many fields.

DNA-Programmed Chemical Synthesis of Polymers and Inorganic Nanomaterials

DNA nanotechnology, based on sequence-specific DNA recognition, could allow programmed self-assembly of sophisticated nanostructures with molecular precision. Extension of this technique to the preparation of broader types of nanomaterials would significantly improve nanofabrication technique to lower nanometer scale and even achieve single molecule operation. Using such exquisite DNA nanostructures as templates, chemical synthesis of polymer and inorganic nanomaterials could also be programmed with unprecedented accuracy and flexibility. This review summarizes recent advances in the synthesis and assembly of polymer and inorganic nanomaterials using DNA nanostructures as templates, and discusses the current challenges and future outlook of DNA templated nanotechnology.

Environment-Recognizing DNA-Computation Circuits for the Intracellular Transport of Molecular Payloads for mRNA Imaging

Programming intelligent DNA nanocarriers for the targeted transport of molecular payloads in living cells has attracted extensive attention. In vivo activation of these nanocarriers usually relies on external light irradiation. An interest is emerging in the automatic recognition of intracellular surroundings by nanocarriers and their in situ activation under the control of programmed DNA-computation circuits. Herein, we report the integration of DNA circuits with framework nucleic acid (FNA) nanocarriers that consist of a truncated square pyramid (TSP) cage and a built-in duplex cargo containing an antisense strand of the target mRNA. An i-motif and ATP aptamer embedded in the TSP are employed as logic-controlling units to respond to H⁺ and ATP inside cellular compartments, triggering the release of the sensing element for fluorescent mRNA imaging. Logic-controlled FNA devices could be used to target drug delivery, enabling precise disease treatment.

Recent Advances of Plasmonic Gold Nanoparticles in Optical Sensing and Therapy

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Gold nanoparticles with special surface plasmon resonance have been widely used in sensing and therapy because of their easy preparation, unique optical properties, excellent biocompatibility, etc. The applications of gold nanoparticles in chemo/biosensing, imaging, and therapy reported in 2016-2019, are summarized in this review. Regarding the gold nanoparticle-based sensing or imaging, sensing mechanisms and strategies are provided to illustrate the concepts for designing sensitive and selective detection platforms. Gold nanoparticlemediated therapy is introduced by surface plasmon resonance-based therapy and delivery-based therapy. Beyond the sole therapeutic system, platforms through synergistic therapy are also discussed. In the end, discussion of the challenges and future trends of gold nanoparticle-based sensing and therapy systems is described.

Surface-decorated nanoparticles clicked into nanoparticle clusters for oligonucleotide encapsulation

Gold nanoparticles (AuNPs) are the predominant and representative metal nano-carriers used for the tumor-targeted delivery of therapeutics because they possess advantages such as biocompatibility, high drug loading efficiency, and enhanced accumulation at tumor sites via the size-dependent enhanced permeability and retention (EPR) effect. In this study, we designed an AuNP functionalized with block polymers comprising polyethylenimine and azide group-functionalized poly(ethyl glycol) for the electrostatic incorporation of cytosine–guanine oligonucleotide (CpG ODN) on the surface. The ODN-incorporated AuNPs were cross-linked to gold nanoparticle clusters (AuNCs) via click chemistry using a matrix metalloproteinase (MMP)-2 cleavable peptide linker modified with alkyne groups at both ends. In the presence of Cu(i), azide groups and alkyne groups spontaneously cyclize to form a triazole ring with high fidelity and efficiency, and therefore allow single AuNPs to stack to larger AuNCs for increased EPR effect-mediated tumor targeting. ¹H-NMR and Fourier transform infrared spectroscopy revealed the successful synthesis of an azide–PEG-grafted branched polyethylenimine, and the size and morphology of AuNPs fabricated by the synthesized polymer were confirmed to be 4.02 ± 0.45 nm by field emission-transmission electron microscopy. Raman spectroscopy characterization demonstrated the introduction of azide groups on the surface of the synthesized AuNPs. Zeta-potential and gel-retardation analysis of CpG-loaded AuNPs indicated complete CpG sequestration by AuNPs when the CpG : AuNP weight ratio was higher than 1 : 2.5. The clustering process of the CpG-loaded AuNPs was monitored and was demonstrated to be dependent on the alkyne linker-to-AuNP ratio. Thus, the clicked AuNC can be tailored as a gene carrier where a high accumulation of therapeutics is required.

AuNPs with bPEI and azide modification are loaded with CpG and self-assembled to AuNCs by click chemistry using an alkyne-terminated MMP-2 cleavable peptide as a linker. The clusters are dissembled by MMP-2 to release CpG in a stimuli-responsive manner.

pH-Controlled Intracellular in Situ Reversible Assembly of a Photothermal Agent for Smart Chemo-Photothermal Synergetic Therapy and ATP Imaging

To advance anti-tumor efficiency and lessen the adverse effect caused by nanodrug residues in the body, a smart nanoagent system is developed and successfully used in intracellular ATP imaging and in vivo chemo-photothermal synergetic therapy. The nanoagent system is facilely prepared using a DNA complex to modify gold nanoparticles (AuNPs). The DNA complex is formed by three oligonucleotides (ATP aptamer, rC-DNA, and rG-DNA). The CG-rich structure in a ternary DNA complex could be exploited for payload of chemotherapeutic medicine doxorubicin (DOX), thus making efficient DOX transport into the tumor site possible. In tumor cells, especially in acidic organelles (e.g., endosome and lysosome), DOX could be rapidly released via the dual stimuli of overexpressed ATP and pH. What is more, the specific recognition of a fluorescently labeled aptamer strand to ATP can achieve the intracellular ATP imaging. pH-controlled reversible folding and unfolding of intermolecular i-motif formed by C-rich strands can lead to intracellular in situ assembly of AuNP aggregates with high photothermal conversion efficiency and promote relatively facile renal clearance of AuNPs through the disassociation of the aggregates in extracellular environments. Experiments in vivo and vitro present feasibility for a synergetic chemo-photothermal therapy. Such an in situ reversible assembly strategy of a chemo-photothermal agent also presents a new paradigm for a smart and highly efficient disease treatment with reduced side effects.

Dual-Signal Readout of DNA Methylation Status Based on the Assembly of a Supersandwich Electrochemical Biosensor without Enzymatic Reaction

A highly sensitive and selective biosensing system was designed to analyze DNA methylation using a dual-signal readout technique in combination with the signal amplification of supersandwich DNA structure. Through the ingenious design of target-triggered cascade of hybridization chain reaction, one target DNA could initiate the formation of supersandwich structure with multiple signal probes. As a result, one-to-multiple amplification effect was achieved, which conferred high sensitivity to target molecular recognition. Based on probe 1 labeled with ferrocene and probe 2 modified with methylene blue, the target DNA was clearly recognized by two electrochemical signals at independent potentials, which was helpful for the acquisition of more accurate detection results. Taking advantage of bisulfite conversion, the methylation status of cytosine (C) was changed to nucleic acid sequence status, which facilitated the hybridization-based detection without enzymatic reaction. Consequently, the methylated DNA was detected at the femtomolar level with satisfactory analytical parameters. The proposed system was effectively used to assess methylated DNA in human blood serum samples, illuminating the possibility of the sensing platform for applications in disease diagnosis and biochemistry research.

Netlike hybridization chain reaction assembly of DNA nanostructures enables exceptional signal amplification for sensing trace cytokines

The monitoring and detection of molecular biomarkers play crucial roles in disease diagnosis and treatment. In this work, we proposed a target-responsive netlike hybridization chain reaction (nHCR) DNA nanostructure construction method, which can offer an exceptional signal enhancement, for highly sensitive fluorescence detection of cytokine, interferon-gamma (IFN-γ). The presence of the target cytokine can lead to the conformational change of the aptamer recognition hairpin probes and the liberation of the nHCR initiator strands, which further trigger the nHCR process between two dye-labeled and double hairpin-structured probes to form netlike DNA nanostructures. The formation of the DNA nanostructures brings the dyes into close proximity, resulting in significantly amplified fluorescence resonance energy transfer signals for sensitive and enzyme-free detection of IFN-γ. The present method has a detection limit of 1.2 pM and a dynamic linear range of 5 to 1000 pM for IFN-γ detection. Besides, with the high specificity of the aptamer probe and the significant signal amplification of the nHCR, such an IFN-γ detection strategy shows excellent selectivity and high sensitivity, which can be potentially applied to detect IFN-γ in human serums. With such a demonstration of the detection of IFN-γ, this proposed method can be extended for detecting different types of biomolecules.

Programmable Self-Assembly of Protein-Scaffolded DNA Nanohydrogels for Tumor-Targeted Imaging and Therapy

DNA hydrogels are biocompatible and are suitable for many biomedical applications. However, to be useful imaging probes or drug carriers, the ordinary bulk size of DNA hydrogels must be overcome. Here we put forward a new strategy for fabricating a novel and simple protein-scaffolded DNA nanohydrogel, constructed through a direct DNA self-assembly using three types of streptavidin (SA)-based DNA tetrad for the activation of imaging and targeting therapy of cancer cells. The DNA nanohydrogels are easily prepared, and we show that by varying the initial concentration of DNA tetrad, it is possible to finely control their size within nanoscale range, which are favorable as carriers for intracellular imaging and transport. By further incorporating therapeutic agents and tumor-targeting MUC1 aptamer, these multifunctionalized SA-scaffolded DNA nanohydrogels (SDH) can specifically target cancer cells and selectively release the preloaded therapeutic agents via a structure switching when in an ATP-rich intracellular environment, leading to the activation of the fluorescence and efficient treatment of cancer cells. With the advantages of facile modular design and assembly, effective cellular uptake, and excellent biocompatibility, the method reported here has the potential for the development of new tunable DNA nanohydrogels with multiple synergistic functionalities for biological and biomedical applications.

Multivalent Self-Assembled DNA Polymer for Tumor-Targeted Delivery and Live Cell Imaging of Telomerase Activity

The efficient detection and in situ monitoring of telomerase activity is of great importance for cancer diagnosis and biomedical research. Here we report for the first time that the development of a novel multivalent self-assembled DNA polymer, constructed through telomerase primer sequence (ITS) triggered hybridization chain assembly using two functional hairpin probes (tumor-trageting aptamer modified H1 and signal probe modified H2), for sensitive detection and imaging of telomerase activity in living cells. After internalizing into the tumor cells by multivalent aptamer targeting, the ITS on DNA polymers can be elongated by intracellular telomerase to generate telomere repeat sequences that are complementary with the signal probe, which can proceed along the DNA polymers, and gradually light up the whole DNA polymers, leading to an enhanced fluorescence signal directly correlated with the activity of telomerase. Our results demonstrated that the developed DNA polymer show excellent performance for specifically detecting telomerase activity in cancer cells, dynamically monitoring the activity change of telomerase in response to telomerase-based drugs, and efficiently distinguishing cancer cells from normal cells. The proposed strategy may afford a valuable tool for the monitoring of telomerase activity in living cells and have great implications for biological and diagnostic applications.