Aptamers Entirely Built from Therapeutic Nucleoside Analogues for Targeted Cancer Therapy

Aptamer-controlled stimuli-responsive drug release

Aptamers have been widely researched and applied in nanomedicine due to their programmable, activatable, and switchable properties. However, there are few reviews on aptamer-controlled stimuli-responsive drug delivery. This article highlights the mechanisms and advantages of aptamers in the construction of stimuli-responsive drug delivery systems. We summarize the assembly/reconfiguration mechanisms of aptamers in controlled release systems. The assembly and drug release strategies of drug delivery systems are illustrated. Specifically, we focus on the binding mechanisms to the target and the factors that induce/inhibit the binding to the stimuli, such as strand, pH, light, and temperature. The applications of aptamer-based stimuli-responsive drug release are elaborated. The challenges are discussed, and the future directions are proposed.

RNA Nanotechnology for Codelivering High-Payload Nucleoside Analogs to Cancer with a Synergetic Effect

Nucleoside analogs are potent inhibitors for cancer treatment, but the main obstacles to their application in humans are their toxicity, nonspecificity, and lack of targeted delivery tools. Here, we report the use of RNA four-way junctions (4WJs) to deliver two nucleoside analogs, floxuridine (FUDR) and gemcitabine (GEM), with high payloads through routine and simple solid-state RNA synthesis and nanoparticle assembly. The design of RNA nanotechnology for the co-delivery of nucleoside analogs and the chemotherapeutic drug paclitaxel (PTX) resulted in synergistic effects and high efficacy in the treatment of Triple-Negative Breast Cancer (TNBC). The 4WJ-drug complexes were confirmed to have efficient tumor spontaneous targeting and no toxicity because the motility of RNA nanoparticles has been previously shown to enable these RNA-drug complexes to spontaneously accumulate in tumor blood vessels. The negative charge of RNA enables those RNA complexes that are not targeted to tumor vasculature to circulate in the blood and enter the urine through the kidney glomerulus, without accumulating in organs, therefore being nontoxic. Drug incorporation into RNA 4WJ can be precisely controlled with a defined loading amount, location, and ratio. The incorporation of nucleoside analogs into 4WJ only requires one step using nucleoside analogue phosphoramidites during solid-phase RNA synthesis, without the need for additional conjugation and purification processes.

High-content tailoring strategy to improve the multifunctionality of functional nucleic acids

Functional nucleic acids (FNAs) have attracted increasing attention in recent years due to their diverse physiological functions. The understanding of their conformational recognition mechanisms has advanced through nucleic acid tailoring strategies and sequence optimization. With the development of the FNA tailoring techniques, they have become a methodological guide for nucleic acid repurposing. Therefore, it is necessary to systematize the relationship between FNA tailoring strategies and the development of nucleic acid multifunctionality. This review systematically categorizes eight types of FNA multifunctionality, and introduces the traditional FNA tailoring strategy from five aspects, including deletion, substitution, splitting, fusion and elongation. Based on the current state of FNA modification, a new generation of FNA tailoring strategy, called the high-content tailoring strategy, was unprecedentedly proposed to improve FNA multifunctionality. In addition, the multiple applications of rational tailoring-driven FNA performance enhancement in various fields were comprehensively summarized. The limitations and potential of FNA tailoring and repurposing in the future are also explored in this review. In summary, this review introduces a novel tailoring theory, systematically summarizes eight FNA performance enhancements, and provides a systematic overview of tailoring applications across all categories of FNAs. The high-content tailoring strategy is expected to expand the application scenarios of FNAs in biosensing, biomedicine and materials science, thus promoting the synergistic development of various fields.

Natural-source payloads used in the conjugated drugs architecture for cancer therapy: Recent advances and future directions

Drug conjugates are obtained from tumor-located vectors connected to cytotoxic agents via linkers, which are designed to deliver hyper-toxic payloads directly to targeted cancer cells. These drug conjugates include antibody-drug conjugates (ADCs), peptide-drug conjugates (PDCs), small molecule-drug conjugates (SMDCs), nucleic acid aptamer-drug conjugates (ApDCs), and virus-like drug conjugate (VDCs), which show great therapeutic value in the clinic. Drug conjugates consist of a targeting carrier, a linker, and a payload. Payloads are key therapy components. Cytotoxic molecules and their derivatives derived from natural products are commonly used in the payload portion of conjugates. The ideal payload should have sufficient toxicity, stability, coupling sites, and the ability to be released under specific conditions to kill tumor cells. Microtubule protein inhibitors, DNA damage agents, and RNA inhibitors are common cytotoxic molecules. Among these conjugates, cytotoxic molecules of natural origin are summarized based on their mechanism of action, conformational relationships, and the discovery of new derivatives. This paper also mentions some cytotoxic molecules that have the potential to be payloads. It also summarizes the latest technologies and novel conjugates developed in recent years to overcome the shortcomings of ADCs, PDCs, SMDCs, ApDCs, and VDCs. In addition, this paper summarizes the clinical trials conducted on conjugates of these cytotoxic molecules over the last five years. It provides a reference for designing and developing safer and more efficient conjugates.

Heterogeneous Electrochemical Carbon Dioxide Reduction in Aqueous Medium Using a Novel N4-Macrocyclic Cobalt Complex

Molecular catalysts represent an exceptional class of materials in the realm of electrochemical carbon dioxide reduction (CO2RR), offering distinct advantages owing to their adaptable structure, which enables precise control of electronic configurations and outstanding performance in CO2RR. This study introduces an innovative approach to heterogeneous electrochemical CO2RR in an aqueous environment, utilizing a newly synthesized N4-macrocyclic cobalt complex generated through a dimerization coupling reaction. By incorporating the quaterpyridine moiety, this cobalt complex exhibits the capability to catalyze CO2RR at low overpotentials and reaches near-unity CO production across a wide potential range, as verified by the online mass spectrometry and in situ attenuated total reflectance-Fourier transform infrared spectroscopy. Comprehensive computational models demonstrate the superiority of utilizing quarterpyridine moiety in mediating CO2 conversion compared to the counterpart. This work not only propels the field of electrochemical CO2RR but also underscores the promising potential of cobalt complexes featuring quaterpyridine moieties in advancing sustainable CO2 conversion technologies within aqueous environments.

Aptamer-Drug conjugates for a targeted and synergistic anticancer Response: Exploiting T30923-5-fluoro-2'-deoxyuridine (INT-FdU) derivatives

One of the most appealing approaches for cancer treatment is targeted therapy, which is based on the use of drugs able to target cancer cells without affecting normal ones. This strategy lets to overcome the major limitation of conventional chemotherapy, namely the lack of specificity of anticancer drugs, which often leads to severe side effects, decreasing the therapy effectiveness. Delivery of cell-killing substances to tumor cells is one-way targeted drug therapy can work. Generally, monoclonal antibodies are combined with chemotherapeutic drugs, allowing cellular uptake through the binding to their targets on the surface of cancer cells. Aptamer-drug conjugates represent a promising alternative solution to antibodies to minimize off-target effects, considering the remarkable selective binding capabilities of aptamers. In this study, to enhance the therapeutic efficacy of the antineoplastic agent 5-fluoro-2'-deoxyuridine (FdU) in various cancer cells, we focused on the development of a novel conjugate using the antiproliferative aptamer T30923 (INT) as a drug vehicle. Three derivatives composed of T30923 conjugated with a different number of FdU units were synthesized, and their structural and biological properties were thoroughly characterized, highlighting their potential for targeted and synergistic anticancer responses.

Modular and automated synthesis of oligonucleotide-small molecule conjugates for cathepsin B mediated traceless release of payloads

The reversible attachment of small molecules to oligonucleotides provides versatile tools for the development of improved oligonucleotide therapeutics. However, cleavable linkers in the oligonucleotide field are scarce, particularly with respect to the requirement for traceless release of the payload in vivo. Herein, we describe a cathepsin B-cleavable dipeptide phosphoramidite, Val-Ala(NB) for the automated synthesis of oligonucleotide-small molecule conjugates. Val-Ala(NB) was protected by a photolabile 2-nitrobenzyl group to improve the stability of the peptide linker during DNA synthesis. Intracellular cathepsin B digests the dipeptide efficiently, releasing the payload-phosphate which is converted to the free payload by endogenous phosphatase enzymes. With the advantages of modular synthesis and stimuli-responsive drug release, we believe Val-Ala(NB) will be a potentially valuable cleavable linker for use in oligonucleotide-drug conjugates.

Development of Bivalent Aptamer-DNA Carrier-Doxorubicin Conjugates for Targeted Killing of Esophageal Squamous Cell Carcinoma Cells

Esophageal cancer ranks the seventh in cancer incidence and the sixth in cancer death. Esophageal squamous cell carcinoma (ESCC) accounts for approximately 90% of the total cases of esophageal cancer. Chemotherapy is the most effective drug-based method for treatment of esophageal cancer. However, severe side effects of traditional chemotherapy limit its treatment efficacy. Targeted chemotherapy can deliver chemotherapeutic drugs to cancer cells and specifically kill these cells with reduced side effects. In the work, the bivalent aptamer-DNA carrier (BAD) was designed by using an ESCC cell-specific aptamer as the recognition molecule and a GC base-rich DNA sequence as the drug carrier. With doxorubicin (Dox) as chemotherapeutic drugs, the bivalent aptamer-DNA-Dox conjugate (BADD) was constructed for targeted killing of ESCC cells. Firstly, the truncated A2(35) aptamer with a retained binding ability was obtained through optimization of an intact A2(80) aptamer and was used to fuse with DNA carrier sequences for constructing the BAD through simple DNA hybridization. The results of gel electrophoresis and flow cytometry analysis showed that the BAD was successfully constructed and had a stronger binding affinity than monovalent A2(35). Then, the BAD was loaded with Dox drugs to construct the BADD through noncovalent intercalation. The results of fluorescence spectra and flow cytometry assays showed that the BADD was successfully constructed and can bind to target cells strongly. Confocal imaging further displayed that the BADD can be specifically internalized into target cells and release Dox. The results of CCK-8 assays, Calcein AM/PI staining, and wound healing assays demonstrated that the BADD can specifically kill target cells, but not control cells. Our results demonstrate that the developed BADD can specifically deliver doxorubicin to target ESCC cells and selectively kill these cells, offering a potentially effective strategy for targeted chemotherapy of ESCC.

Drugtamer-PROTAC Conjugation Strategy for Targeted PROTAC Delivery and Synergistic Antitumor Therapy

Proteolysis-targeting chimeras (PROTACs) have emerged as a promising strategy for targeted protein degradation and drug discovery. To overcome the inherent limitations of conventional PROTACs, an innovative drugtamer-PROTAC conjugation approach is developed to enhance tumor targeting and antitumor potency. Specifically, a smart prodrug is designed by conjugating "drugtamer" to a nicotinamide phosphoribosyltransferase (NAMPT) PROTAC using a tumor microenvironment responsible linker. The "drugtamer" consists of fluorouridine nucleotide and DNA-like oligomer. Compared to NAMPT PROTAC and the combination of PROTAC + fluorouracil, the designed prodrug AS-2F-NP demonstrates superior tumor targeting, efficient cellular uptake, improved in vivo potency and reduced side effects. This study provides a promising strategy for the precise delivery of PROTAC and synergistic antitumor agents.

Programmable melanoma-targeted radio-immunotherapy via fusogenic liposomes functionalized with multivariate-gated aptamer assemblies

Radio-immunotherapy exploits the immunostimulatory features of ionizing radiation (IR) to enhance antitumor effects and offers emerging opportunities for treating invasive tumor indications such as melanoma. However, insufficient dose deposition and immunosuppressive microenvironment (TME) of solid tumors limit its efficacy. Here we report a programmable sequential therapeutic strategy based on multifunctional fusogenic liposomes (Lip@AUR-ACP-aptPD-L1) to overcome the intrinsic radio-immunotherapeutic resistance of solid tumors. Specifically, fusogenic liposomes are loaded with gold-containing Auranofin (AUR) and inserted with multivariate-gated aptamer assemblies (ACP) and PD-L1 aptamers in the lipid membrane, potentiating melanoma-targeted AUR delivery while transferring ACP onto cell surface through selective membrane fusion. AUR amplifies IR-induced immunogenic death of melanoma cells to release antigens and damage-associated molecular patterns such as adenosine triphosphate (ATP) for triggering adaptive antitumor immunity. AUR-sensitized radiotherapy also upregulates matrix metalloproteinase-2 (MMP-2) expression that combined with released ATP to activate ACP through an "and" logic operation-like process (AND-gate), thus triggering the in-situ release of engineered cytosine-phosphate-guanine aptamer-based immunoadjuvants (eCpG) for stimulating dendritic cell-mediated T cell priming. Furthermore, AUR inhibits tumor-intrinsic vascular endothelial growth factor signaling to suppress infiltration of immunosuppressive cells for fostering an anti-tumorigenic TME. This study offers an approach for solid tumor treatment in the clinics.

A Tumor-Specific Cascade-Activating Smart Prodrug System for Enhanced Targeted Therapy

Developing intelligently targeted drugs with low side effects is urgent for cancer treatment. Toward this goal, a tumor-specific cascade-activating smart prodrug system consisting of a G-quadruplex(G4)-modulated tumor-targeted DNA vehicle and a well-designed cellular stimuli-responsive ligand-drug conjugates (LDCs) is proposed. An original "donor-acceptor" binary fluorescent ligand, with ultrahigh affinity, brightness, and photostability, is engineered to tightly bind G4 structures and significantly improve the nuclease resistance of the DNA vehicle, which serves as a bridge contributing to the construction of the prodrug system, named ApG4/LDCs. Sodium nitroprusside and doxorubicin are loaded into ApG4/LDCs in one pot and generate nitric oxide and superoxide anion in response to cancer cellular environments, which in cascade generates peroxynitrite to cause DNA damage while promoting the self-monitored drug release to achieve enhanced targeted therapy. Such a cascade activation and self-reinforcement process is executed only when the prodrug system targets the tumor tissue followed by cell uptake, showing significant antitumor efficacy and greatly weakening the damage to normal tissues. Given the unique features, the innovative strategy for prodrug design may open a new door to precision disease treatment.

Polyfluoroalkyl Tag Decoration Enables Significantly Enhanced Tumor Penetration Ability of a PTK7 Targeting Aptamer

Aptamers are widely used molecular recognition tools in targeted therapy, but their ability to effectively penetrate deep into solid tumors remains a significant challenge, leading to suboptimal treatment efficacy. Here, we developed a polyfluoroalkyl (PFA) decoration strategy to enhance aptamer recognition, cell internalization, and solid tumor penetration. Our results indicate that PFA with around 11 fluorine atoms significantly improves aptamer internalization both in vitro and in vivo settings. However, we also observed that the use of PFA tags containing 19 and 23 fluorine atoms on aptamers resulted in nonspecific cell anchoring in control cell lines, affecting the specificity of aptamers. Overall, we found that using a chemical modification strategy could enhance the deep tumor penetration ability of aptamers and validate their effectiveness in vivo. This approach has significant practical applications in targeted drug delivery for cancer treatment.

Intelligent Biomaterialomics: Molecular Design, Manufacturing, and Biomedical Applications

Materialomics integrates experiment, theory, and computation in a high-throughput manner, and has changed the paradigm for the research and development of new functional materials. Recently, with the rapid development of high-throughput characterization and machine-learning technologies, the establishment of biomaterialomics that tackles complex physiological behaviors has become accessible. Breakthroughs in the clinical translation of nanoparticle-based therapeutics and vaccines have been observed. Herein, recent advances in biomaterials, including polymers, lipid-like materials, and peptides/proteins, discovered through high-throughput screening or machine learning-assisted methods, are summarized. The molecular design of structure-diversified libraries; high-throughput characterization, screening, and preparation; and, their applications in drug delivery and clinical translation are discussed in detail. Furthermore, the prospects and main challenges in future biomaterialomics and high-throughput screening development are highlighted.

Engineering aspects of lipid-based delivery systems: In vivo gene delivery, safety criteria, and translation strategies

Defects in the genome cause genetic diseases and can be treated with gene therapy. Due to the limitations encountered in gene delivery, lipid-based supramolecular colloidal materials have emerged as promising gene carrier systems. In their non-functionalized form, lipid nanoparticles often demonstrate lower transgene expression efficiency, leading to suboptimal therapeutic outcomes, specifically through reduced percentages of cells expressing the transgene. Due to chemically active substituents, the engineering of delivery systems for genetic drugs with specific chemical ligands steps forward as an innovative strategy to tackle the drawbacks and enhance their therapeutic efficacy. Despite intense investigations into functionalization strategies, the clinical outcome of such therapies still needs to be improved. Here, we highlight and comprehensively review engineering aspects for functionalizing lipid-based delivery systems and their therapeutic efficacy for developing novel genetic cargoes to provide a full snapshot of the translation from the bench to the clinics. We outline existing challenges in the delivery and internalization processes and narrate recent advances in the functionalization of lipid-based delivery systems for nucleic acids to enhance their therapeutic efficacy and safety. Moreover, we address clinical trials using these vectors to expand their clinical use and principal safety concerns.

Polyvalent Aptamer-Functionalized NIR-II Quantum Dots for Targeted Theranostics in High PD-L1-Expressing Tumors

Ag2S quantum dots (QDs) show superior optical properties in the NIR-II region and display significant clinical potential with favorable biocompatibility. However, inherent defects of low targeting and poor solubility necessitate practical modification methods to achieve the theranostics of Ag2S QDs. Herein, we used rolling circle amplification (RCA) techniques to obtain long single-stranded DNA containing the PD-L1 aptamer and C-rich DNA palindromic sequence. The C-rich DNA palindromic sequences can specifically chelate Ag2+ and thus serve as a template to result in biomimetic mineralization and formation of pApt-Ag2S QDs. These QDs enable specific targeting and illuminate hot tumors with high PD-L1 expression effectively, serving as excellent molecular targeted probes. In addition, due to the high NIR-II absorption of Ag2S QDs, pApt-Ag2S QDs exhibit remarkable photothermal properties. And besides, polyvalent PD-L1 aptamers can recognize PD-L1 protein and effectively block the inhibitory signal of PD-L1 on T cells, enabling efficient theranostics through the synergistic effect of photothermal therapy and immune checkpoint blocking therapy. Summary, we enhance the biological stability and antibleaching ability of Ag2S QDs using long single-stranded DNA as a template, thereby establishing a theranostic platform that specifically targets PD-L1 high-expressing inflamed tumors and demonstrates excellent performance both in vitro and in vivo.

Applications of peptide-based nanomaterials in targeting cancer therapy

To meet the demand for precision medicine, researchers are committed to developing novel strategies to reduce systemic toxicity and side effects in cancer treatment. Targeting peptides are widely applied due to their affinity and specificity, and their ability to be high-throughput screened, chemically synthesized and modified. More importantly, peptides can form ordered self-assembled structures through non-covalent supramolecular interactions, which can form nanostructures with different morphologies and functions, playing crucial roles in targeted diagnosis and treatment. Among them, in targeted immunotherapy, utilizing targeting peptides to block the binding between immune checkpoints and ligands, thereby activating the immune system to eliminate cancer cells, is an advanced therapeutic strategy. In this mini-review, we summarize the screening, self-assembly, and biomedical applications of targeting peptide-based nanomaterials. Furthermore, this mini-review summarizes the potential and optimization strategies of targeting peptides.

Chemically Modified Platforms for Better RNA Therapeutics

RNA-based therapies have catalyzed a revolutionary transformation in the biomedical landscape, offering unprecedented potential in disease prevention and treatment. However, despite their remarkable achievements, these therapies encounter substantial challenges including low stability, susceptibility to degradation by nucleases, and a prominent negative charge, thereby hindering further development. Chemically modified platforms have emerged as a strategic innovation, focusing on precise alterations either on the RNA moieties or their associated delivery vectors. This comprehensive review delves into these platforms, underscoring their significance in augmenting the performance and translational prospects of RNA-based therapeutics. It encompasses an in-depth analysis of various chemically modified delivery platforms that have been instrumental in propelling RNA therapeutics toward clinical utility. Moreover, the review scrutinizes the rationale behind diverse chemical modification techniques aiming at optimizing the therapeutic efficacy of RNA molecules, thereby facilitating robust disease management. Recent empirical studies corroborating the efficacy enhancement of RNA therapeutics through chemical modifications are highlighted. Conclusively, we offer profound insights into the transformative impact of chemical modifications on RNA drugs and delineates prospective trajectories for their future development and clinical integration.

Selection and identification of a prohibitin 2-binding DNA aptamer for tumor tissue imaging and targeted chemotherapy

Tumor cell-targeting molecules play a vital role in cancer diagnosis, targeted therapy, and biomarker discovery. Aptamers are emerging as novel targeting molecules with unique advantages in cancer research. In this work, we have developed several DNA aptamers through cell-based systematic evolution of ligands by exponential enrichment (Cell-SELEX). The selected SYL-6 aptamer can bind to a variety of cancer cells with high signal. Tumor tissue imaging demonstrated that SYL-6-Cy5 fluorescent probe was able to recognize multiple clinical tumor tissues but not the normal tissues, which indicates great potential of SYL-6 for clinical tumor diagnosis. Meanwhile, we identified prohibitin 2 (PHB2) as the molecular target of SYL-6 using mass spectrometry, pull-down and RNA interference assays. Moreover, SYL-6 can be used as a delivery vehicle to carry with doxorubicin (Dox) chemotherapeutic agents for antitumor targeted chemotherapy. The constructed SYL-6-Dox can not only selectively kill tumor cells in vitro, but also inhibit tumor growth with reduced side effects in vivo. This work may provide a general tumor cell-targeting molecule and a potential biomarker for cancer diagnosis and targeted therapy.

Aptamer functionalized gold nanoclusters as an emerging nanoprobe in biosensing, diagnostic, catalysis and bioimaging

DNA nanostructures, with their fascinating luminescent and detecting capabilities, provide a basis that can accommodate a wide range of applications. The unique electronic configurations, and physical and chemical properties of aptamer-assembled gold nanoclusters (apt-AuNCs) as a novel type of fluorophore have gradually piqued the interest of the scientific community. Bending DNA sequences and other templates/legends as a stabilizing agent with Au metal has produced an abundance of biosensors, along with catalytic and imaging properties. This review article summarizes the synthesis, conjugation tactics, advantages, and sensing mechanisms of AuNCs aptasensor after providing a brief introduction to the topic. Moreover, the application of DNA/aptamer functionalization has been briefly discussed in the fields of food safety and quality, catalysis, clinical diagnosis, cancer cell bioimaging, detection of cancer cell indicators, and therapy. We also concluded the current obstacles and made recommendations about the future prospects of AuNCs for fundamental research and applications in line with the developments in DNA/aptamer-AuNCs.

Photoactivatable Aptamer-CRISPR Nanodevice Enables Precise Profiling of Interferon-Gamma Release in Humanized Mice

Real-time dynamic imaging of immunoactivation-related cytokines is crucial for evaluating the efficacy of immune checkpoint blockade therapy and optimizing the treatment regimen. We introduce herein a spatiotemporally controlled nanodevice that allows in situ photoactivated imaging of interferon-gamma (IFN-γ) secretion from T cells in vitro and in vivo. The nanodevice is constructed by rational engineering of an aptamer-embedded, UV-cleavable PC-DNA probe and further integration with upconversion nanoparticles- and CRISPR-Cas12a-enhanced fluorescence systems. Using human peripheral blood mononuclear cells (PBMC)-engrafted mouse models, this nanodevice allows for the quantitative imaging of endogenous IFN-γ and its intratumoral dynamics responding to antiprogrammed cell death receptor 1 (anti-PD-1) therapy. This study thus provides a toolbox for boosting the sensitivity and precision of cytokine imaging during immune checkpoint blockade therapy, enlightening research toward imaging-guided tumor therapy.

Rational Engineering of a Multifunctional DNA Assembly for Enhanced Antibacterial Efficacy and Accelerated Wound Healing

DNA-based assemblies hold immense prospects for antibacterial application, yet are constrained by their poor specificity and deficient antibacterial delivery. Herein, the fabrication of a versatile rolling circle amplification (RCA)-sustained DNA assembly is reported, encoding simultaneously with multivalent aptamers and tandem antibacterial agents, for target-specific and efficient antibacterial application. In the compact RCA-sustained antibacterial platform, the facilely organized multivalent aptamers guarantee the target bacteria-specific delivery of sufficient antibacterial agents which is assembled through DNA-stabilizing silver nanostructures. It is shown that the biocompatible DNA system could enhance bacteria elimination and simultaneously facilitate wound healing in vivo. By virtue of the programmable RCA assembly, the present RCA-sustained system provides a highly modular and scalable approach to design versatile multifunctional therapeutic systems.

Target-triggered cascade signal amplification in nanochannels: An ingenious strategy for ultrasensitive photoelectrochemical DNA bioanalysis

Artificial solid-state nanochannels have aroused intense interests in biosensors and bioelectronics because of their special architectures. Herein, we pioneered an ingenious approach of target-triggered cascade signal amplification in porous anodic aluminum oxide (AAO) nanochannels for ultrasensitive photoelectrochemical (PEC) DNA bioanalysis. In the design, AAO nanochannels were modified initially with capture DNA (cDNA) and then incorporated with a photoelectrode, yielding the desired architecture of highly ordered nanoarrays on top of the signal transducer. For target DNA (tDNA) probing, exonuclease III (Exo-III) mediated target recycling (ETR) was first activated to generate plenty of output DNA (oDNA) fragments. After oDNA and the conjugate of Au-labeled probe DNA (Au-pDNA) were anchored within the nanochannels via DNA hybridization, in-situ synthesis of Ag shells on tethered Au nanoparticles was conducted. The resulting large-sized Au@Ag core-shell nanostructure within the nanochannels would cause conspicuous blocking effect to hinder the transportation of electrons accessing the photoelectrode. Since the signal inhibition was directly related to tDNA concentration, an innovative nanochannels PEC DNA assay was exploited and qualified for ultrasensitive detection. The anti-interference ability of this platform was also emphasized by the split AAO membrane for biological incubation without participation of the photoelectrode. This featured nanochannels PEC strategy with cascade amplification launched a novel detecting platform for trace levels of DNA, and it could spark more inspiration for a follow-up exploration of other smart nanochannels PEC bioassays.

Modified nucleic acid aptamers: development, characterization, and biological applications

Aptamers are single-stranded oligonucleotides that bind to their targets via specific structural interactions. To improve the properties and performance of aptamers, modified nucleotides are incorporated during or after a selection process such as systematic evolution of ligands by exponential enrichment (SELEX). We summarize the latest modified nucleotides and strategies used in modified (mod)-SELEX and post-SELEX to develop modified aptamers, highlight the methods used to characterize aptamer-target interactions, and present recent progress in modified aptamers that recognize different targets. We discuss the challenges and perspectives in further advancing the methodologies and toolsets to accelerate the discovery of modified aptamers, improve the throughput of aptamer-target characterization, and expand the functional diversity and complexity of modified aptamers.

A cocktail therapeutic strategy based on clofarabine-containing aptamer-PROTAC for enhanced cancer therapy

By introducing a therapeutic nucleoside analogue tail to the parent Aptamer-PROTACs, a PROTAC-cocktail system (ApTCs-3X) was designed and evaluated. ApTCs-3X exhibited improved nuclease resistance and efficiently degraded target protein with subcellular localization preference. This cocktail therapy results in enhanced therapeutic outcomes, making it suitable for advancing PROTAC in combination therapy.

Chemical Amplification-Enabled Topological Modification of Nucleic Acid Aptamers for Enhanced Cancer-Targeted Theranostics

Site-specific chemical conjugation has long been a challenging endeavor in the field of ligand-directed modification to produce homogeneous conjugates for precision medicine. Here, we develop a chemical amplification-enabled topological modification (Chem-ATM) methodology to establish a versatile platform for the programmable modification of nucleic acid aptamers with designated functionalities. Differing from conventional conjugation strategies, a three-dimensional artificial base is designed in Chem-ATM as a chemical amplifier, giving access to structurally and functionally diversified conjugation of aptamers, with precise control over loading capacity but in a sequence-independent manner. Meanwhile, the sp3 hybridized atom-containing amplifier enables planar-to-stereo conformational transformation of the entire conjugate, eliciting high steric hindrance against enzymatic degradation in complex biological environments. The versatility of Chem-ATM is successfully demonstrated by its delivery of anticancer drugs and imaging agents for enhanced therapy and high-contrast noninvasive tumor imaging in xenograft and orthotopic tumor models. This study offers a different perspective for ligand-directed chemical conjugation to enrich the molecular toolbox for bioimaging and drug development.

Self-Assembled Multivalent Aptamer Drug Conjugates: Enhanced Targeting and Cytotoxicity for HER2-Positive Gastric Cancer

Antibody drug conjugates (ADCs) have shown promise to be the mainstream chemotherapeutics for advanced HER2-positive cancers, yet the issues of poor drug delivery efficiency, limited chemotherapeutic effects, severe immune responses, and drug resistance remain to be addressed before the clinical applications of ADCs. The DNA aptamer-guided drug conjugates (ApDCs) are receiving growing attention for specific tumors due to their excellent tumor affinity and low cost. Therefore, developing a multivalent ApDC nanomedicine by combining anti-HER2 aptamer (HApt), tetrahedral framework nucleic acid (tFNA), and deruxtecan (Dxd) together to form HApt-tFNA@Dxd might help to address these concerns. In this study, the HER2-targeted DNA aptamer modified DNA tetrahedron (HApt-tFNA) was employed as a system for drug delivery, and the adoption of tFNA could effectively enlarge the drug-loading rate compared to aptamer-guided ApDCs previously reported. Compared with free Dxd and tFNA@Dxd, HApt-tFNA@Dxd showed better structural stability, excellent targeted cytotoxicity to HER2-positive gastric cancer, and increased tissue aggregation ability in tumors. These features and superiorities make HApt-tFNA@Dxd a promising chemotherapeutic medicine for HER2-positive tumors. Our work developed a new targeting nanomedicine by combining DNA nanomaterials and chemotherapeutic agents, which represents a critical advance toward developing novel DNA-based nanomaterials and promoting their potential applications for HER2-positive cancer therapy.

Terminal Alkyne-Modified DNA Aptamers with Enhanced Protein Binding Affinities

Nucleic acid-based receptors, known as aptamers, are relatively fast to discover and manufacture but lack the diverse functional groups of protein receptors (e.g., antibodies). The binding properties of DNA aptamers can be enhanced by attaching abiotic functional groups; for example, aromatic groups such as naphthalene slow dissociation from proteins. Although the terminal alkyne is a π-electron-rich functional group that has been used in small molecule drugs to enhance binding to proteins through noncovalent interactions, it remains unexplored for enhancing DNA aptamer binding affinity. Here, we demonstrate the utility of the terminal alkyne for improving the binding of DNA to proteins. We prepared a library of 256 terminal-alkyne-bearing variants of HD22, a DNA aptamer that binds the protein thrombin with nanomolar affinity. After a one-step thrombin-binding selection, a high-affinity aptamer containing two alkynes was discovered, exhibiting 3.2-fold tighter thrombin binding than the corresponding unmodified sequence. The tighter binding was attributable to a slower rate of dissociation from thrombin (5.2-fold slower than HD22). Molecular dynamics simulations with enhanced sampling by Replica Exchange with Solute Tempering (REST2) suggest that the π-electron-rich alkyne interacts with an asparagine side chain N-H group on thrombin, forming a noncovalent interaction that stabilizes the aptamer-protein interface. Overall, this work represents the first case of terminal alkynes enhancing the binding properties of an aptamer and underscores the utility of the terminal alkyne as an atom economical π-electron-rich functional group to enhance binding affinity with minimal steric perturbation.

Conjugating 4β-NH-(5-Aminoindazole)-podophyllotoxin and Galectin-1-Targeted Aptamer for Synergistic Chemo-Immunotherapy of Hepatocellular Carcinoma

By conjugating a chemotherapeutic candidate drug 4β-NH-(5-aminoindazole)-podophyllotoxin (βIZP) and an immunosuppressive protein galectin-1 targeted aptamer AP74, a chemo-immunotherapy molecule (AP74-βIZP) is developed against liver cancer. AP74-βIZP can target galectin-1 and enrich the tumor microenvironment to improve the tumor inhibition ratio by 6.3%, higher than that of βIZP in a HepG2 xenograft model. In safety evaluation, βIZP cannot be released from AP74-βIZP in normal tissues with low glutathione level. Therefore, the degrees of organs injury and myelosuppression after the treatment with AP74-βIZP are lower than those with βIZP. After 21 d treatment at a drug dose of 5 mg kg-1 , AP74-βIZP does not cause weight loss in mice, while the weight is significantly reduced by 24% and 14% from oxaliplatin and βIZP, respectively. In immune synergy, AP74-IZP enhances CD4/CD8 cell infiltration to promote the expression of cell factor (i.e., IL-2, TNF-α, and IFN-γ), which further improves the antitumor activity. The tumor inhibition ratio of AP74-βIZP is 70.2%, which is higher than that of AP74 (35.2%) and βIZP (48.8%). Because of the dual effects of chemotherapy and immunotherapy, AP74-βIZP exhibits superior activity and lower toxicity. The approach developed in this work could be applicable to other chemotherapy drugs.

Nucleoside-based anticancer drugs: Mechanism of action and drug resistance

Nucleoside-based drugs, recognized as purine or pyrimidine analogs, have been potent therapeutic agents since their introduction in 1950, deployed widely in the treatment of diverse diseases such as cancers, myelodysplastic syndromes, multiple sclerosis, and viral infections. These antimetabolites establish complex interactions with cellular molecular constituents, primarily via activation of phosphorylation cascades leading to consequential interactions with nucleic acids. However, the therapeutic efficacy of these agents is frequently compromised by the development of drug resistance, a continually emerging challenge in their clinical application. This comprehensive review explores the mechanisms of resistance to nucleoside-based drugs, encompassing a wide spectrum of phenomena from alterations in membrane transporters and activating kinases to changes in drug elimination strategies and DNA damage repair mechanisms. The critical analysis in this review underlines complex interactions of drug and cell and also guides towards novel therapeutic strategies to counteract resistance. The development of targeted therapies, novel nucleoside analogs, and synergistic drug combinations are promising approaches to restore tumor sensitivity and improve patient outcomes.

Chemical Tailoring of Aptamer Glues with Significantly Enhanced Recognition Ability for Targeted Membrane Protein Degradation

Cell membrane proteins play a crucial role in the development of early cancer diagnosis strategies and precision medicine techniques. However, the application of aptamers in cell membrane protein-based biomedical research is limited by their inherent drawbacks, such as sensitivity to the recognition environment and susceptibility to enzymatic degradation, which leads to the loss of recognition ability. To address these challenges, this study presents a subzero-temperature-enabled molecule stacking strategy for the on-demand tailoring of aptamer glues for the precision recognition and efficient degradation of membrane protein. Mechanistic studies revealed that nucleic acid molecule stacking occurred during the freezing and melting processes, facilitating a rapid click reaction by bringing two reactive groups together. In vitro investigations demonstrated that the strategy confers aptamer glues with significantly enhanced specific recognition ability and binding affinity, allowing the distinction of a targeted cell line from a nontargeted cell line. Moreover, the engineered aptamer glue exhibited impressive targeted cell membrane protein degradation ability; around 74% of the c-Met protein was degraded in 24 h. These findings hold great potential for advancing cancer diagnosis and targeted therapy through the development of more stable and reliable aptamer probes.

Complexation of drug and hapten-conjugated aptamer with universal hapten antibody for pancreatic cancer treatment

Owing to a lack of reliable markers and therapeutic targets, pancreatic ductal adenocarcinoma (PDAC) remains the most lethal malignant tumor despite numerous therapeutic advances. In this study, we utilized cell-SELEX to isolate a DNA aptamer recognizing the natural conformation of the target on the cell surface. PAp7T8, an aptamer optimized by size and chemical modification, exhibited specific targeting to pancreatic cancer cells and orthotopic xenograft pancreatic tumors. To confer therapeutic functions to the aptamer, we adopted a drug-conjugated oligobody (DOligobody) strategy. Monomethyl auristatin E was used as a cytotoxic drug, digoxigenin acted as a hapten, and the humanized anti-digoxigenin antibody served as a universal carrier of the aptamer. The resulting PAp7T8-DOligobody showed extended in vivo half-life and markedly inhibited tumor growth in an orthotopic pancreatic cancer xenograft model without causing significant toxicity. Therefore, PAp7T8-DOligobody represents a promising novel therapeutic delivery platform for PDAC.

Drug-Grafted DNA for Cancer Therapy

With the development of solid-phase synthesis and DNA nanotechnology, DNA-based drug delivery systems have seen large advancements over the past decades. By combining various drugs (small-molecular drugs, oligonucleotides, peptides, and proteins) with DNA technology, drug-grafted DNA has demonstrated great potential as a promising platform in recent years, in which complementary properties of both components have been discovered; for instance, the synthesis of amphiphilic drug-grafted DNA has enabled the production of DNA nanomedicines for gene therapy and chemotherapy. Through the design of linkages between drug and DNA parts, stimuli-responsiveness can be instilled, which has boosted the application of drug-grafted DNA in various biomedical applications such as cancer therapy. This review discusses the progress of various drug-grafted DNA therapeutic agents, exploring the synthetic techniques and anticancer applications afforded through the combination of drug and nucleic acids.

Molecular Complementarity of Proteomimetic Materials for Target-Specific Recognition and Recognition-Mediated Complex Functions

As biomolecules essential for sustaining life, proteins are generated from long chains of 20 different α-amino acids that are folded into unique 3D structures. In particular, many proteins have molecular recognition functions owing to their binding pockets, which have complementary shapes, charges, and polarities for specific targets, making these biopolymers unique and highly valuable for biomedical and biocatalytic applications. Based on the understanding of protein structures and microenvironments, molecular complementarity can be exhibited by synthesizable and modifiable materials. This has prompted researchers to explore the proteomimetic potentials of a diverse range of materials, including biologically available peptides and oligonucleotides, synthetic supramolecules, inorganic molecules, and related coordination networks. To fully resemble a protein, proteomimetic materials perform the molecular recognition to mediate complex molecular functions, such as allosteric regulation, signal transduction, enzymatic reactions, and stimuli-responsive motions; this can also expand the landscape of their potential bio-applications. This review focuses on the recognitive aspects of proteomimetic designs derived for individual materials and their conformations. Recent progress provides insights to help guide the development of advanced protein mimicry with material heterogeneity, design modularity, and tailored functionality. The perspectives and challenges of current proteomimetic designs and tools are also discussed in relation to future applications.

Targeting tumor endothelial cells with methyltransferase inhibitors: Mechanisms of action and the potential of combination therapy

Tumor endothelial cells (TECs) reside in the inner lining of blood vessels and represent a promising target for targeted cancer therapy. DNA methylation is a chemical process that involves the transfer of a methyl group to a specific base in the DNA strand, catalyzed by DNA methyltransferase (DNMT). DNMT inhibitors (DNMTis) can inhibit the activity of DNMTs, thereby preventing the transfer of methyl groups from s-adenosyl methionine (SAM) to cytosine. Currently, the most viable therapy for TECs is the development of DNMTis to release cancer suppressor genes from their repressed state. In this review, we first outline the characteristics of TECs and describe the development of tumor blood vessels and TECs. Abnormal DNA methylation is closely linked to tumor initiation, progression, and cell carcinogenesis, as evidenced by numerous studies. Therefore, we summarize the role of DNA methylation and DNA methyltransferase and the therapeutic potential of four types of DNMTi in targeting TECs. Finally, we discuss the accomplishments, challenges, and opportunities associated with combination therapy with DNMTis for TECs.

An aptamer-based depot system for sustained release of small molecule therapeutics

Delivery of hydrophilic small molecule therapeutics by traditional drug delivery systems is challenging. Herein, we have used the specific interaction between DNA aptamers and drugs to create simple and effective drug depot systems. The specific binding of a phosphorothioate-modified aptamer to drugs formed non-covalent aptamer/drug complexes, which created a sustained release system. We demonstrated the effectiveness of this system with small hydrophilic molecules, the site 1 sodium channel blockers tetrodotoxin and saxitoxin. The aptamer-based delivery system greatly prolonged the duration of local anesthesia and reduced systemic toxicity. The beneficial effects of the aptamers were restricted to the compounds they were specific to. These studies establish aptamers as a class of highly specific, modifiable drug delivery systems, and demonstrate potential usefulness in the management of postoperative pain.

DNA-Based Nanomaterials as Drug Delivery Platforms for Increasing the Effect of Drugs in Tumors

DNA nanotechnology has significantly advanced and might be used in biomedical applications, drug delivery, and cancer treatment during the past few decades. DNA nanomaterials are widely used in biomedical research involving biosensing, bioimaging, and drug delivery since they are remarkably addressable and biocompatible. Gradually, modified nucleic acids have begun to be employed to construct multifunctional DNA nanostructures with a variety of architectural designs. Aptamers are single-stranded nucleic acids (both DNAs and RNAs) capable of self-pairing to acquire secondary structure and of specifically binding with the target. Diagnosis and tumor therapy are prospective fields in which aptamers can be applied. Many DNA nanomaterials with three-dimensional structures have been studied as drug delivery systems for different anticancer medications or gene therapy agents. Different chemical alterations can be employed to construct a wide range of modified DNA nanostructures. Chemically altered DNA-based nanomaterials are useful for drug delivery because of their improved stability and inclusion of functional groups. In this work, the most common oligonucleotide nanomaterials were reviewed as modern drug delivery systems in tumor cells.

Toehold-Exchange-Based Activation of Aptamer Switches Enables High Thermal Robustness and Programmability

Aptamer switches are attractive nature-inspired tools for developing smart materials and nanodevices. However, the thermal robustness and programmability of current aptamer switches are often limited by their activation processes that are coupled with high reaction enthalpy. Here, we present an enthalpy-independent activation approach that harnesses toehold-exchange as a general framework to design aptamer switches. We demonstrate mathematically and experimentally that this approach is highly effective in improving thermal robustness and thus leads to better analytical performances of aptamer switches. Enhanced programmability is also demonstrated through fine-grained and dynamic tuning of effective affinities and dynamic ranges, as well as the construction of a synthetic DNA network that resembled biological signaling cascades. Our study not only enriches the current toolbox for engineering and controlling synthetic molecular switches but also offers new insights into their thermodynamic basis, which is critical for diverse synthetic biological designs and applications.

Aptamer nucleotide analog drug conjugates in the targeting therapy of cancers

Aptamers are short single-strand oligonucleotides that can form secondary and tertiary structures, fitting targets with high affinity and specificity. They are so-called "chemical antibodies" and can target specific biomarkers in both diagnostic and therapeutic applications. Systematic evolution of ligands by exponential enrichment (SELEX) is usually used for the enrichment and selection of aptamers, and the targets could be metal ions, small molecules, nucleotides, proteins, cells, or even tissues or organs. Due to the high specificity and distinctive binding affinity of aptamers, aptamer-drug conjugates (ApDCs) have demonstrated their potential role in drug delivery for cancer-targeting therapies. Compared with antibodies which are produced by a cell-based bioreactor, aptamers are chemically synthesized molecules that can be easily conjugated to drugs and modified; however, the conventional ApDCs conjugate the aptamer with an active drug using a linker which may add more concerns to the stability of the ApDC, the drug-releasing efficiency, and the drug-loading capacity. The function of aptamer in conventional ApDC is just as a targeting moiety which could not fully perform the advantages of aptamers. To address these drawbacks, scientists have started using active nucleotide analogs as the cargoes of ApDCs, such as clofarabine, ara-guanosine, gemcitabine, and floxuridine, to replace all or part of the natural nucleotides in aptamer sequences. In turn, these new types of ApDCs, aptamer nucleotide analog drug conjugates, show the strength for targeting efficacy but avoid the complex drug linker designation and improve the synthetic efficiency. More importantly, these classic nucleotide analog drugs have been used for many years, and aptamer nucleotide analog drug conjugates would not increase any unknown druggability risk but improve the target tumor accumulation. In this review, we mainly summarized aptamer-conjugated nucleotide analog drugs in cancer-targeting therapies.

Aptamers as Smart Ligands for Targeted Drug Delivery in Cancer Therapy

Undesirable side effects and multidrug tolerance are the main holdbacks to the treatment of cancer in conventional chemotherapy. Fortunately, targeted drug delivery can improve the enrichment of drugs at the target site and reduce toxicity to normal tissues and cells. A targeted drug delivery system is usually composed of a nanocarrier and a targeting component. The targeting component is called a "ligand". Aptamers have high target affinity and specificity, which are identified as attractive and promising ligands. Therefore, aptamers have potential application in the development of smart targeting systems. For instance, aptamers are able to efficiently recognize tumor markers such as nucleolin, mucin, and epidermal growth factor receptor (EGFR). Besides, aptamers can also identify glycoproteins on the surface of tumor cells. Thus, the aptamer-mediated targeted drug delivery system has received extensive attention in the application of cancer therapy. This article reviews the application of aptamers as smart ligands for targeted drug delivery in cancer therapy. Special interest is focused on aptamers as smart ligands, aptamer-conjugated nanocarriers, aptamer targeting strategy for tumor microenvironment (TME), and aptamers that are specified to crucial cancer biomarkers for targeted drug delivery.

XNAzymes targeting the SARS-CoV-2 genome inhibit viral infection

The unprecedented emergence and spread of SARS-CoV-2, the coronavirus responsible for the COVID-19 pandemic, underscores the need for diagnostic and therapeutic technologies that can be rapidly tailored to novel threats. Here, we show that site-specific RNA endonuclease XNAzymes - artificial catalysts composed of single-stranded synthetic xeno-nucleic acid oligonucleotides (in this case 2'-deoxy-2'-fluoro-β-D-arabino nucleic acid) - may be designed, synthesised and screened within days, enabling the discovery of a range of enzymes targeting SARS-CoV-2 ORF1ab, ORF7b, spike- and nucleocapsid-encoding RNA. Three of these are further engineered to self-assemble into a catalytic nanostructure with enhanced biostability. This XNA nanostructure is capable of cleaving genomic SARS-CoV-2 RNA under physiological conditions, and when transfected into cells inhibits infection with authentic SARS-CoV-2 virus by RNA knockdown. These results demonstrate the potential of XNAzymes to provide a platform for the rapid generation of antiviral reagents.

The Landscape of Nucleic-Acid-Based Aptamers for Treatment of Hematologic Malignancies: Challenges and Future Directions

Hematologic malignancies, including leukemia, lymphoma, myeloproliferative disorder and plasma cell neoplasia, are genetically heterogeneous and characterized by an uncontrolled proliferation of their corresponding cell lineages in the bone marrow, peripheral blood, tissues or plasma. Although there are many types of therapeutic drugs (e.g., TKIs, chemotherapy drugs) available for treatment of different malignancies, the relapse, drug resistance and severe side effects due to the lack of selectivity seriously limit their clinical application. Currently, although antibody-drug conjugates have been well established as able to target and deliver highly potent chemotherapy agents into cancer cells for the reduction of damage to healthy cells and have achieved success in leukemia treatment, they still also have shortcomings such as high cost, high immunogenicity and low stability. Aptamers are ssDNA or RNA oligonucleotides that can also precisely deliver therapeutic agents into cancer cells through specifically recognizing the membrane protein on cancer cells, which is similar to the capabilities of monoclonal antibodies. Aptamers exhibit higher binding affinity, lower immunogenicity and higher thermal stability than antibodies. Therefore, in this review we comprehensively describe recent advances in the development of aptamer-drug conjugates (ApDCs) with cytotoxic payload through chemical linkers or direct incorporation, as well as further introduce the latest promising aptamers-based therapeutic strategies such as aptamer-T cell therapy and aptamer-PROTAC, clarifying their bright application, development direction and challenges in the treatment of hematologic malignancies.

Engineering the Surface Properties of DNA Nanostructures by Tuning the Valency of Assembling Species for Biomedical Applications

Self-assembled DNA nanostructures hold great potentials in biomedical applications. Nevertheless, the negatively charged DNA backbone and susceptivity to enzyme degradation pose challenges to this regard. Engineering the surface properties of DNA nanostructures by assembling DNA with guest molecules in magnesium-free system is promising to solve these issues. In this study, the polyamines-mediated DNA self-assembly with an emphasis on the valency of polyamines is investigated. Both spermine, spermidine, and putrescine can assemble DNA tetrahedron under appropriate concentrations. The cytotoxicity and cellular uptake efficiencies vary with the polyamine valency. Compared with magnesium-assembled DNA tetrahedron, polyamine-assembled DNA tetrahedron exhibits higher cellular uptake efficiency and serum stability. Circular dichroism spectrum results indicate that polyamines induce DNA conformation slightly shifting from B form to A form. The improved performances of polyamine-assembled DNA tetrahedrons under physiological settings are attributed to the surface properties that altered by guest molecules polyamine. The current study suggests that engineering the surface properties of DNA nanostructures by assembling them with guest cationic species is promising to further their biomedical applications.

Self-assembled peptide-paclitaxel nanoparticles for enhancing therapeutic efficacy in colorectal cancer

Chemotherapy is one of the main treatments for colorectal cancer, but systemic toxicity severely limits its clinical use. Packaging hydrophobic chemotherapeutic drugs in targeted nanoparticles greatly improve their efficacy and reduce side effects. We previously identified a novel colorectal cancer specific binding peptide P-LPK (LPKTVSSDMSLN) from phage display peptide library. Here we designed a self-assembled paclitaxel (PTX)-loaded nanoparticle (LPK-PTX NPs). LPK-PTX NPs displayed a superior intracellular internalization and improved tumor cytotoxicity in vitro. Cy5.5-labeled LPK-PTX NPs showed much higher tumor accumulation in colorectal cancer-bearing mice. Furthermore, LPK-PTX NPs exhibit enhanced antitumor activity and decreased systemic toxicity in colorectal cancer patient-derived xenografts (PDX) model. The excellent in vitro and in vivo antitumor efficacy proves the improved targeting drug delivery, suggesting that peptide P-LPK has potential to provide a novel approach for enhanced drug delivery with negligible systemic toxicity.

Redox-labelled electrochemical aptasensors with nanosupported cancer cells

The transfer of redox-labelled bioelectrochemical sensors from proteins to cells is not straightforward because of the cell downward force issue on the surface of the sensors. In this paper, 20-nm-thick nanopillars are introduced to overcome this issue, in a well-controlled manner. We show on both molecular dynamics simulations and experiments that suspending cells a few nanometers above an electrode surface enables redox-labelled tethered DNA aptamer probes to move freely, while remaining at an interaction distance from a target membrane protein, i. e. epithelial cell adhesion molecule (EpCAM), which is typically overexpressed in cancer cells. By this nanopillar configuration, the interaction of aptamer with cancer cells is clearly observable, with 13 cells as the lower limit of detection. Nanoconfinement induced by the gap between the electrode surface and the cell membrane appears to improve the limit of detection and to lower the melting temperature of DNA aptamer hairpins, offering an additional degree of freedom to optimize molecular recognition mechanisms. This novel nanosupported electrochemical DNA cell sensor scheme including Brownian-fluctuating redox species opens new opportunities for the design of all-electrical sensors using redox-labelled probes.