Oligonucleotide-Modified Gold Nanoparticles for Intracellular Gene Regulation

Role of nanomaterials in deactivating multiple drug resistance efflux pumps - A review

The changes in lifestyle and living conditions have affected not only humans but also microorganisms. As man invents new drugs and therapies, pathogens alter themselves to survive and thrive. Multiple drug resistance (MDR) is the talk of the town for decades now. Many generations of medications have been termed useless as MDR rises among the infectious population. The surge in nanotechnology has brought a new hope in reducing this aspect of resistance in pathogens. It has been observed in several laboratory-based studies that the use of nanoparticles had a synergistic effect on the antibiotic being administered to the pathogen; several resistant strains scummed to the stress created by the nanoparticles and became susceptible to the drug. The major cause of resistance to date is the efflux system, which makes the latest generation of antibiotics ineffective without reaching the target site. If species-specific nanomaterials are used to control the activity of efflux pumps, it could revolutionize the field of medicine and make the previous generation resistant medications active once again. Therefore, the current study was devised to assess and review nanoparticles' role on efflux systems and discuss how specialized particles can be designed towards an infectious host's particular drug ejection systems.

Self-Assembly of Nanodiamonds and Plasmonic Nanoparticles for Nanoscopy

Nanodiamonds have emerged as promising agents for sensing and imaging due to their exceptional photostability and sensitivity to the local nanoscale environment. Here, we introduce a hybrid system composed of a nanodiamond containing nitrogen-vacancy center that is paired to a gold nanoparticle via DNA hybridization. Using multiphoton optical studies, we demonstrate that the harmonic mode emission generated in gold nanoparticles induces a coupled fluorescence emission in nanodiamonds. We show that the flickering of harmonic emission in gold nanoparticles directly influences the nanodiamonds' emissions, resulting in stochastic blinking. By utilizing the stochastic emission fluctuations, we present a proof-of-principle experiment to demonstrate the potential application of the hybrid system for super-resolution microscopy. The introduced system may find applications in intracellular biosensing and bioimaging due to the DNA-based coupling mechanism and also the attractive characteristics of harmonic generation, such as low power, low background and tissue transparency.

Fast microwave heating-based one-step synthesis of DNA and RNA modified gold nanoparticles

DNA/RNA-gold nanoparticle (DNA/RNA-AuNP) nanoprobes have been widely employed for nanobiotechnology applications. Here, we discover that both thiolated and non-thiolated DNA/RNA can be efficiently attached to AuNPs to achieve high-stable spherical nucleic acid (SNA) within minutes under a domestic microwave (MW)-assisted heating-dry circumstance. Further studies show that for non-thiolated DNA/RNA the conjugation is poly (T/U) tag dependent. Spectroscopy, test strip hybridization, and loading counting experiments indicate that low-affinity poly (T/U) tag mediates the formation of a standing-up conformation, which is distributed in the outer layer of SNA structure. In further application studies, CRISPR/Cas9-sgRNA (136 bp), SARS-CoV-2 RNA fragment (1278 bp), and rolling circle amplification (RCA) DNA products (over 1000 bp) can be successfully attached on AuNPs, which overcomes the routine methods in long-chain nucleic acid-AuNP conjugation, exhibiting great promise in biosensing and nucleic acids delivery applications. Current heating-dry strategy has improved traditional DNA/RNA-AuNP conjugation methods in simplicity, rapidity, cost, and universality.

Simple methods for attaching polynucleotides to gold nanoparticles are of interest for simplifying conjugation in a range of applications. Here, the authors report a microwave heating-based method for the fast, one-step attachment of a range of thiolated or non-thiolated DNA and RNA to gold nanoparticles.

Nucleic Acids and Their Analogues for Biomedical Applications

Nucleic acids are emerging as powerful and functional biomaterials due to their molecular recognition ability, programmability, and ease of synthesis and chemical modification. Various types of nucleic acids have been used as gene regulation tools or therapeutic agents for the treatment of human diseases with genetic disorders. Nucleic acids can also be used to develop sensing platforms for detecting ions, small molecules, proteins, and cells. Their performance can be improved through integration with other organic or inorganic nanomaterials. To further enhance their biological properties, various chemically modified nucleic acid analogues can be generated by modifying their phosphodiester backbone, sugar moiety, nucleobase, or combined sites. Alternatively, using nucleic acids as building blocks for self-assembly of highly ordered nanostructures would enhance their biological stability and cellular uptake efficiency. In this review, we will focus on the development and biomedical applications of structural and functional natural nucleic acids, as well as the chemically modified nucleic acid analogues over the past ten years. The recent progress in the development of functional nanomaterials based on self-assembled DNA-based platforms for gene regulation, biosensing, drug delivery, and therapy will also be presented. We will then summarize with a discussion on the advanced development of nucleic acid research, highlight some of the challenges faced and propose suggestions for further improvement.

Rationally designed DNA therapeutics can modulate human TH expression by controlling specific GQ formation in its promoter

Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the catecholamine (CA) biosynthesis pathway, making TH a molecular target for controlling CA production, specifically dopamine. Dysregulation of dopamine is correlated with neurological diseases such as Parkinson's disease (PD) and post-traumatic stress disorder (PTSD), among others. Previously, we showed that a 49-nucleotide guanine (G)-rich sequence within the human TH promoter adopts two different sets of G-quadruplex (GQ) structures (5'GQ and 3'GQ), where the 5'GQ uses G-stretches I, II, IV, and VI in TH49, which enhances TH transcription, while the 3'GQ utilizes G-stretches II, IV, VI, and VII, which represses transcription. Herein, we demonstrated targeted switching of these GQs to their active state using rationally designed DNA GQ Clips (5'GQ and 3'GQ Clips) to modulate endogenous TH gene expression and dopamine production. As a translational approach, we synthesized a targeted nanoparticle delivery system to effectively deliver the 5'GQ Clip in vivo. We believe this strategy could potentially be an improved approach for controlling dopamine production in a multitude of neurological disorders, including PD.

Protein transfection via spherical nucleic acids

The efficient transfection of functional proteins into cells can serve as a means for regulating cellular processes toward solving fundamental challenges in biology and medicine. However, the use of proteins as effective intracellular agents is hindered by their low cellular uptake and susceptibility to degradation. Over the past 15 years, our group has been developing spherical nucleic acids (SNAs), nanoparticles functionalized with a dense radially oriented shell of nucleic acids. These structures actively enter cells and have opened new frontiers in chemical sensing, biodiagnostics and therapeutics. Recently, we have shown that proteins can be used as structurally precise and homogeneous nanoparticle cores in SNAs. The resultant protein SNAs (ProSNAs) allow previously cell-impermeable proteins to actively enter cells, exhibit high degrees of stability and activity both in cell culture and in vivo, and show enhanced pharmacokinetics. Consequently, these modular structures constitute a plug-and-play platform in which the protein core and nucleic acid shell can be independently varied to achieve a desired function. Here, we describe the synthesis of ProSNAs through the chemical modification of solvent-accessible surface residues (3-5 d). We also discuss design considerations, strategies for characterization, and applications of ProSNAs in cellular transfection, biological sensing and functional enzyme delivery in vivo.

Spherical nucleic acids: Organized nucleotide aggregates as versatile nanomedicine

Spherical nucleic acids (SNAs) are composed of a nanoparticle core and a layer of densely arranged oligonucleotide shells. After the first report of SNA by Mirkin and coworkers in 1996, it has created a significant interest by offering new possibilities in the field of gene and drug delivery. The controlled aggregation of oligonucleotides on the surface of organic/inorganic nanoparticles improves the delivery of genes and nucleic acid-based drugs and alters and regulates the biological profiles of the nanoparticle core within living organisms. Here in this review, we present an overview of the recent progress of SNAs that has speeded up their biomedical application and their potential transition to clinical use. We start with introducing the concept and characteristics of SNAs as drug/gene delivery systems and highlight recent efforts of bioengineering SNA by imaging and treatmenting various diseases. Finally, we discuss potential challenges and opportunities of SNAs, their ongoing clinical trials, and future translation, and how they may affect the current landscape of clinical practices. We hope that this review will update our current understanding of SNA, organized oligonucleotide aggregates, for disease diagnosis and treatment.

Assembly of Bleomycin Saccharide-Decorated Spherical Nucleic Acids

Glyco-decorated spherical nucleic acids (SNAs) may be attractive delivery vehicles, emphasizing the sugar-specific effect on the outer sphere of the construct and at the same time hiding unfavorable distribution properties of the loaded oligonucleotides. As examples of such nanoparticles, tripodal sugar constituents of bleomycin were synthesized and conjugated with a fluorescence-labeled antisense oligonucleotide (AONARV7). Successive copper(I)-catalyzed azide-alkyne and strain-promoted alkyne-nitrone cycloadditions (SPANC) were utilized for the synthesis. Then, the glyco-AONARV7 conjugates were hybridized with complementary strands of a C60-based molecular spherical nucleic acid (i.e., a hybridization-mediated carrier). The formation and stability of these assembled glyco-decorated SNAs were evaluated by polyacrylamide gel electrophoresis (PAGE), UV melting profile analysis, and time-resolved fluorescence spectroscopy. Association constants were extracted from time-resolved fluorescence data. Preliminary cellular uptake experiments of the glyco-AONARV7 conjugates (120 nM solutions) and of the corresponding glyco-decorated SNAs (10 nM solutions) with human prostate cancer cells (PC3) showed an efficient uptake in each case. A marked variation in intracellular distribution was observed.

An Investigation into the Resistance of Spherical Nucleic Acids against DNA Enzymatic Degradation

Nanoparticles coated with oligonucleotides, also termed spherical nucleic acids (SNAs), are at the forefront of scientific research and have been applied in vitro and in vivo for sensing, gene regulation, and drug delivery. They demonstrate unique properties stemming from the three-dimensional shell of oligonucleotides and present high cellular uptake. However, their resistance to enzymatic degradation is highly dependent on their physicochemical characteristics. In particular, the oligonucleotide loading of SNAs has been determined to be a critical parameter in SNA design. In order to ensure the successful function of SNAs, the degree of oligonucleotide loading has to be quantitatively determined to confirm that a dense oligonucleotide shell has been achieved. However, this can be time-consuming and may lead to multiple syntheses being required to achieve the necessary degree of surface functionalization. In this work we show how this limitation can be overcome by introducing an oligonucleotide modification. By replacing the phosphodiester bond on the oligonucleotide backbone with a phosphorothioate bond, SNAs even with a low DNA loading showed remarkable stability in the presence of nucleases. Furthermore, these chemically modified SNAs exhibited high selectivity and specificity toward the detection of mRNA in cellulo.

Engineered Aptamer-Organic Amphiphile Self-Assemblies for Biomedical Applications: Progress and Challenges

Currently, nucleic acid aptamers are exploited as robust targeting ligands in the biomedical field, due to their specific molecular recognition, little immunogenicity, low cost, ect. Thanks to the facile chemical modification and high hydrophilicity, aptamers can be site-specifically linked with hydrophobic moieties to prepare aptamer-organic amphiphiles (AOAs), which spontaneously assemble into aptamer-organic amphiphile self-assemblies (AOASs). These polyvalent self-assemblies feature with enhanced target-binding ability, increased resistance to nuclease, and efficient cargo-loading, making them powerful platforms for bioapplications, including targeted drug delivery, cell-based cancer therapy, biosensing, and bioimaging. Besides, the morphology of AOASs can be elaborately manipulated for smarter biomedical functions, by regulating the hydrophilicity/hydrophobicity ratio of AOAs. Benefiting from the boom in DNA synthesis technology and nanotechnology, various types of AOASs, including aptamer-polymer amphiphile self-assemblies, aptamer-lipid amphiphile self-assemblies, aptamer-cell self-assemblies, ect, have been constructed with great biomedical potential. Particularly, stimuli-responsive AOASs with transformable structure can realize site-specific drug release, enhanced tumor penetration, and specific target molecule detection. Herein, the general synthesis methods of oligonucleotide-organic amphiphiles are firstly summarized. Then recent progress in different types of AOASs for bioapplications and strategies for morphology control are systematically reviewed. The present challenges and future perspectives of this field are also discussed.

Delivery of therapeutic oligonucleotides in nanoscale

Therapeutic oligonucleotides (TOs) represent one of the most promising drug candidates in the targeted cancer treatment due to their high specificity and capability of modulating cellular pathways that are not readily druggable. However, efficiently delivering of TOs to cancer cellular targets is still the biggest challenge in promoting their clinical translations. Emerging as a significant drug delivery vector, nanoparticles (NPs) can not only protect TOs from nuclease degradation and enhance their tumor accumulation, but also can improve the cell uptake efficiency of TOs as well as the following endosomal escape to increase the therapeutic index. Furthermore, targeted and on-demand drug release of TOs can also be approached to minimize the risk of toxicity towards normal tissues using stimuli-responsive NPs. In the past decades, remarkable progresses have been made on the TOs delivery based on various NPs with specific purposes. In this review, we will first give a brief introduction on the basis of TOs as well as the action mechanisms of several typical TOs, and then describe the obstacles that prevent the clinical translation of TOs, followed by a comprehensive overview of the recent progresses on TOs delivery based on several various types of nanocarriers containing lipid-based nanoparticles, polymeric nanoparticles, gold nanoparticles, porous nanoparticles, DNA/RNA nanoassembly, extracellular vesicles, and imaging-guided drug delivery nanoparticles.

Polymer-based Non-viral Vectors for Gene Therapy in the Skin

Gene therapy has emerged as a versatile technique with the potential to treat a range of human diseases; however, examples of the topical application of gene therapy as a treatment...

Gold-Polymer Nanocomposites for Future Therapeutic and Tissue Engineering Applications

Gold nanoparticles (AuNPs) have been extensively investigated for their use in various biomedical applications. Owing to their biocompatibility, simple surface modifications, and electrical and unique optical properties, AuNPs are considered promising nanomaterials for use in in vitro disease diagnosis, in vivo imaging, drug delivery, and tissue engineering applications. The functionality of AuNPs may be further expanded by producing hybrid nanocomposites with polymers that provide additional functions, responsiveness, and improved biocompatibility. Polymers may deliver large quantities of drugs or genes in therapeutic applications. A polymer alters the surface charges of AuNPs to improve or modulate cellular uptake efficiency and their biodistribution in the body. Furthermore, designing the functionality of nanocomposites to respond to an endo- or exogenous stimulus, such as pH, enzymes, or light, may facilitate the development of novel therapeutic applications. In this review, we focus on the recent progress in the use of AuNPs and Au-polymer nanocomposites in therapeutic applications such as drug or gene delivery, photothermal therapy, and tissue engineering.

Self-Protected DNAzyme Walker with a Circular Bulging DNA Shield for Amplified Imaging of miRNAs in Living Cells and Mice

Abnormal expression of miRNAs is often detected in various human cancers. DNAzyme machines combined with gold nanoparticles (AuNPs) hold promise for detecting specific miRNAs in living cells but show short circulation time due to the fragility of catalytic core. Using miRNA-21 as the model target, by introducing a circular bulging DNA shield into the middle of the catalytic core, we report herein a self-protected DNAzyme (E) walker capable of fully stepping on the substrate (S)-modified AuNP for imaging intracellular miRNAs. The DNAzyme walker exhibits 5-fold enhanced serum resistance and more than 8-fold enhanced catalytic activity, contributing to the capability to image miRNAs much higher than commercial transfection reagent and well-known FISH technique. Diseased cells can accurately be distinguished from healthy cells. Due to its universality, DNAzyme walker can be extended for imaging other miRNAs only by changing target binding domain, indicating a promising tool for cancer diagnosis and prognosis.

Delineating the Role of Tailored Gold Nanostructures at the Biointerface

Gold (Au) has emerged as a superior element, because of its widespread applications in electronic and medical fields. The desirable physical, chemical, optical, and inherent enzyme-like properties of Au are efficiently exploited for detection, diagnostic, and therapeutic purposes. Au offers a unique advantage of fabricating gold nanostructures (GNS) having exact physical, chemical, optical, and enzyme-like properties required for the specific biomedical application. In this Review, the emerging trend of GNS for various biomedical applications is highlighted. Some notable structural and chemical modifications achieved for the detection of biomolecules, pathogens, diagnosis of diseases, and therapeutic applications are discussed in brief. The limitations of GNS during biomedical usage are highlighted and the way forward to overcome these limitations are discussed.

DNA-coated gold nanoparticles for tracking hepatocyte growth factor secreted by transplanted mesenchymal stem cells in pulmonary fibrosis therapy

The identification of paracrine factors secreted by transplanted mesenchymal stem cells (MSCs) during the treatment of idiopathic pulmonary fibrosis (IPF) is essential for understanding the role of MSCs in therapy. Herein, we report a facile and efficient strategy for in vivo tracking the secretion of hepatocyte growth factor (HGF) in MSCs during IPF therapy. In our strategy, a novel nanoflare tracer consisting of gold nanoparticles (AuNPs), complementary sequences and dye-labeled recognition sequences is developed. Briefly, the AuNPs are functionalized with oligonucleotide complementary sequences hybridized to the organic dye-labeled recognition sequences, where the organic fluorophores are in close proximity to the AuNPs. In the absence of targets, the dye and AuNPs are separated from each other, inducing the quenching of the fluorescence signal. However, in the presence of targets, the recognition sequences gradually fall off from the AuNPs, causing the fluorescence signal to rise. In brief, in vivo monitoring of the dynamic expression of HGF mRNA in transplanted MSCs during IPF therapy in the current work may provide new insight into the paracrine process of the transplanted MSCs, thereby advancing the MSC-based IPF therapy toward clinical applications.

Nanogold-based materials in medicine: from their origins to their future

The properties of gold-based materials have been explored for centuries in several research fields, including medicine. Multiple published production methods for gold nanoparticles (AuNPs) have shown that the physicochemical and optical properties of AuNPs depend on the production method used. These different AuNP properties have allowed exploration of their usefulness in countless distinct biomedical applications over the last few years. Here we present an extensive overview of the most commonly used AuNP production methods, the resulting distinct properties of the AuNPs and the potential application of these AuNPs in diagnostic and therapeutic approaches in biomedicine.

Tango of dual nanoparticles: Interplays between exosomes and nanomedicine

Exosomes are lipid bilayer vesicles released from cells as a mechanism of intracellular communication. Containing information molecules of their parental cells and inclining to fuse with targeted cells, exosomes are valuable in disease diagnosis and drug delivery. The realization of their clinic applications still faces difficulties, such as lacking technologies for fast purification and functional reading. The advancement of nanotechnology in recent decades makes it promising to overcome these difficulties. In this article, we summarized recent progress in utilizing the physiochemical properties of nanoparticles (NPs) to enhance exosome purification and detection sensitivity or to derive novel technologies. We also discussed the valuable applications of exosomes in NPs‐based drug delivery. Till now most studies in these fields are still at the laboratory research stage. Translation of these bench works into clinic applications still has a long way to go.

Plasmonic Chiral Metamaterials with Sub-10 nm Nanogaps

Sub-10 nm nanogaps are enantioselectively fabricated between two nanocrescents based on nanoskiving and show tailored circular dichroism (CD) activity. The mirror symmetry of the nanostructure is broken by subsequent deposition with different azimuthal angles. Strong plasmonic coupling is excited in the gaps and at the tips, leading to the CD activity. The dissymmetry g-factor of the chiral nanogaps with 5 nm gap-width is -0.055, which is 2.5 times stronger than that of the 10 nm gap-width. Moreover, the surface-enhanced Raman scattering (SERS) performance of l/d-cysteine absorbed on chiral nanogaps manifests as the emergence of enantiospecific Raman peaks and the appearance of distinct changes in SERS intensities, which affirms that chiral nanogaps can recognize specific cysteine enantiomers via standard Raman spectroscopy in the absence of circularly polarized light source and a chiral label molecule. The sub-10 nm chiral nanogaps with tailored chiroptical responses show great potential in a class of chiral applications, such as chiral sensing, polarization converters, label-free chiral recognition, and asymmetric catalysis.

Anticancer Potential of Green Synthesized Silver Nanoparticles of the Soft Coral Cladiella pachyclados Supported by Network Pharmacology and In Silico Analyses

Cladiella-derived natural products have shown promising anticancer properties against many human cancer cell lines. In the present investigation, we found that an ethyl acetate extract of Cladiella pachyclados (CE) collected from the Red Sea could inhibit the human breast cancer (BC) cells (MCF and MDA-MB-231) in vitro (IC50 24.32 ± 1.1 and 9.55 ± 0.19 µg/mL, respectively). The subsequent incorporation of the Cladiella extract into the green synthesis of silver nanoparticles (AgNPs) resulted in significantly more activity against both cancer cell lines (IC50 5.62 ± 0.89 and 1.72 ± 0.36, respectively); the efficacy was comparable to that of doxorubicin with much-enhanced selectivity. To explore the mode of action of this extract, various in silico and network-pharmacology-based analyses were performed in the light of the LC-HRESIMS-identified compounds in the CE extract. Firstly, using two independent machine-learning-based prediction software platforms, most of the identified compounds in CE were predicted to inhibit both MCF7 and MDA-MB-231. Moreover, they were predicted to have low toxicity towards normal cell lines. Secondly, approximately 242 BC-related molecular targets were collected from various databases and used to construct a protein-protein interaction (PPI) network, which revealed the most important molecular targets and signaling pathways in the pathogenesis of BC. All the identified compounds in the extract were then subjected to inverse docking against all proteins hosted in the Protein Data bank (PDB) to discover the BC-related proteins that these compounds can target. Approximately, 10.74% of the collected BC-related proteins were potential targets for 70% of the compounds identified in CE. Further validation of the docking results using molecular dynamic simulations (MDS) and binding free energy calculations revealed that only 2.47% of the collected BC-related proteins could be targeted by 30% of the CE-derived compounds. According to docking and MDS experiments, protein-pathway and compound-protein interaction networks were constructed to determine the signaling pathways that the CE compounds could influence. This paper highlights the potential of marine natural products as effective anticancer agents and reports the discovery of novel anti-breast cancer AgNPs.

Spherical Nucleic Acid Vaccine Structure Markedly Influences Adaptive Immune Responses of Clinically Utilized Prostate Cancer Targets

Cancer vaccines, which activate the immune system against a target antigen, are attractive for prostate cancer, where multiple upregulated protein targets are identified. However, many clinical trials implementing peptides targeting these proteins have yielded suboptimal results. Using spherical nucleic acids (SNAs), we explore how precise architectural control of vaccine components can activate a robust antigen-specific immune response in comparison to clinical formulations of the same targets. The SNA vaccines incorporate peptides for human prostate-specific membrane antigen (PSMA) or T-cell receptor γ alternate reading frame protein (TARP) into an optimized architecture, resulting in high rates of immune activation and cytolytic ability in humanized mice and human peripheral blood mononuclear cells (hPBMCs). Specifically, administered SNAs elevate the production and secretion of cytokines and increase polyfunctional cytotoxic T cells and effector memory. Importantly, T cells raised from immunized mice potently kill targets, including clinically relevant cells expressing the whole PSMA protein. Treatment of hPBMCs increases costimulatory markers and cytolytically active T cells. This work demonstrates the importance of vaccine structure and its ability to reformulate and elevate clinical targets. Moreover, it encourages the field to reinvestigate ineffective peptide targets and repackage them into optimally structured vaccines to harness antigen potency and enhance clinical outcomes.

Biointeraction of Erythrocyte Ghost Membranes with Gold Nanoparticles Fluorescents

The application of new technologies for treatments against different diseases is increasingly innovative and effective. In the case of nanomedicine, the combination of nanoparticles with biological membranes consists of a “camouflage” technique, which improves biological interaction and minimizes the secondary effects caused by these remedies. In this work, gold nanoparticles synthesized by chemical reduction (Turkevich ≈13 nm) were conjugated with fluorescein isothiocyanate to amplify their optical properties. Fluorescent nanoparticles were deposited onto the surface of hemoglobin-free erythrocytes. Ghost erythrocytes were obtained from red blood cells by density gradient separation in a hypotonic medium and characterized with fluorescence, optical, and electron microscopy; the average size of erythrocyte ghosts was 9 µm. Results show that the functional groups of sodium citrate (COO-) and fluorophore (-N=C=S) adhere by electrostatic attraction to the surface of the hemoglobin-free erythrocyte membrane, forming the membrane–particle–fluorophore. These interactions can contribute to imaging applications, by increasing the sensitivity of measurement caused by surface plasmon resonance and fluorescence, in the context of biological membranes.

Spherical Nucleic Acids: Integrating Nanotechnology Concepts into General Chemistry Curricula

Nanoscience and technology research offer exciting avenues to modernize undergraduate-level General Chemistry curricula. In particular, spherical nucleic acid (SNA) nanoconjugates, which behave as "programmable atom equivalents" (PAEs) in the context of colloidal crystals, are one system that one can use to reinforce foundational concepts in chemistry including matter and atoms, the Periodic Table, Lewis dot structures and the octet rule, valency and valence-shell electron-pair repulsion (VSEPR) theory, and Pauling's rules, ultimately leading to enriching discussions centered on materials chemistry and biochemistry with key implications in medicine, optics, catalysis, and other areas. These lessons connect historical and modern concepts in chemistry, relate course content to current professional and popular science topics, inspire critical and creative thinking, and spur some students to continue their science, technology, engineering, and mathematics (STEM) education and attain careers in STEM fields. Ultimately, and perhaps most importantly, these lessons may expand the pool of young students interested in chemistry by making connections to a broader group of contemporary concepts and technologies that impact their lives and enhance their view of the field. Herein, a way of teaching aspects of General Chemistry in the context of modern nanoscience concepts is introduced to instructors and curricula developers at research institutions, primarily undergraduate institutions, and community colleges worldwide.

Controlling the Biological Fate of Liposomal Spherical Nucleic Acids Using Tunable Polyethylene Glycol Shells

Liposomal spherical nucleic acids (LSNAs) modified with polyethylene glycol (PEG) units are studied in an attempt to understand how the circulation time and biodistribution of the constructs can be manipulated. Specifically, the effect of (1) PEG molecular weight, (2) PEG shell stability, and (3) PEG modification method (PEG in both the core and shell versus PEG in the shell only) on LSNA blood circulation, biodistribution, and in vivo cell internalization in a syngeneic, orthotopic triple-negative breast cancer mouse model is studied. Generally, high PEG molecular weight extends blood circulation lifetime, and a more lipophilic anchor stabilizes the PEG shell and improves circulation and tumor accumulation but at the cost of cell uptake efficiency. The PEGylation strategy has a minor effect on in vitro properties of LSNAs but significantly alters in vivo cell uptake. For example, surface-only PEG in one design contributed to higher in vivo cell internalization than its counterpart with PEG both in the shell and core. Taken together, this work provides guidelines for designing LSNAs that exhibit maximal in vivo cancer cell uptake characteristics in the context of a breast cancer model.

Oligonucleotide-Functionalized Gold Nanoparticles for Synchronous Telomerase Inhibition, Radiosensitization, and Delivery of Theranostic Radionuclides

Telomerase represents an attractive target in oncology as it is expressed in cancer but not in normal tissues. The oligonucleotide inhibitors of telomerase represent a promising anticancer strategy, although poor cellular uptake can restrict their efficacy. In this study, gold nanoparticles (AuNPs) were used to enhance oligonucleotide uptake. "match" oligonucleotides complementary to the telomerase RNA template subunit (hTR) and "scramble" (control) oligonucleotides were conjugated to diethylenetriamine pentaacetate (DTPA) for 111In-labeling. AuNPs (15.5 nm) were decorated with a monofunctional layer of oligonucleotides (ON-AuNP) or a multifunctional layer of oligonucleotides, PEG(polethylene glycol)800-SH (to reduce AuNP aggregation) and the cell-penetrating peptide Tat (ON-AuNP-Tat). Match-AuNP enhanced the cellular uptake of radiolabeled oligonucleotides while retaining the ability to inhibit telomerase activity. The addition of Tat to AuNPs increased nuclear localization. 111In-Match-AuNP-Tat induced DNA double-strand breaks and caused a dose-dependent reduction in clonogenic survival of telomerase-positive cells but not telomerase-negative cells. hTR inhibition has been reported to sensitize cancer cells to ionizing radiation, and 111In-Match-AuNP-Tat therefore holds promise as a vector for delivery of radionuclides into cancer cells while simultaneously sensitizing them to the effects of the emitted radiation.

Collaborative Equilibrium Coupling of Catalytic DNA Nanostructures Enables Programmable Detection of SARS-CoV-2

Accessible and adaptable nucleic acid diagnostics remains a critical challenge in managing the evolving COVID-19 pandemic. Here, an integrated molecular nanotechnology that enables direct and programmable detection of SARS-CoV-2 RNA targets in native patient specimens is reported. Termed synergistic coupling of responsive equilibrium in enzymatic network (SCREEN), the technology leverages tunable, catalytic molecular nanostructures to establish an interconnected, collaborative architecture. SCREEN mimics the extraordinary organization and functionality of cellular signaling cascades. Through programmable enzyme-DNA nanostructures, SCREEN activates upon interaction with different RNA targets to initiate multi-enzyme catalysis; through system-wide favorable equilibrium shifting, SCREEN directly transduces a single target binding into an amplified electrical signal. To establish collaborative equilibrium coupling in the architecture, a computational model that simulates all reactions to predict overall performance and optimize assay configuration is developed. The developed platform achieves direct and sensitive RNA detection (approaching single-copy detection), fast response (assay reaction is completed within 30 min at room temperature), and robust programmability (across different genetic loci of SARS-CoV-2). When clinically evaluated, the technology demonstrates robust and direct detection in clinical swab lysates to accurately diagnose COVID-19 patients.

Gold Nanoparticles: Multifaceted Roles in the Management of Autoimmune Disorders

Gold nanoparticles (GNPs) have been recently applied for various diagnostic and therapeutic purposes. The unique properties of these nanoparticles (NPs), such as relative ease of synthesis in various sizes, shapes and charges, stability, high drug-loading capacity and relative availability for modification accompanied by non-cytotoxicity and biocompatibility, make them an ideal field of research in bio-nanotechnology. Moreover, their potential to alleviate various inflammatory factors, nitrite species, and reactive oxygen production and the capacity to deliver therapeutic agents has attracted attention for further studies in inflammatory and autoimmune disorders. Furthermore, the characteristics of GNPs and surface modification can modulate their toxicity, biodistribution, biocompatibility, and effects. This review discusses in vitro and in vivo effects of GNPs and their functionalized forms in managing various autoimmune disorders (Ads) such as rheumatoid arthritis, type 1 diabetes, and multiple sclerosis.

Broad-Spectrum Polymeric Nanoquencher as an Efficient Fluorescence Sensing Platform for Biomolecular Detection

Colloidal inorganic nanostructures (metal, carbon, and silica) have been widely used as "nanoquenchers" for construction of nanosensors; however, inherent drawbacks such as insufficient fluorescence quenching efficiency, false positive signals, and uncertain long-term cytotoxicity have limited their further utility. Herein, by taking advantages of polymeric nanoparticles (PNPs) in terms of high loading capacity, facile surface modification chemistry, and good biocompatibility, we report a broad-spectrum (400-750 nm) polymeric fluorescence-quenching platform for sensor fabrication. Our newly developed polymeric nanoquenchers (qPNPs) were constructed by concurrently encapsulating various alkylated black-hole quenchers into nanoparticles made of poly(methyl methacrylate-co-methacrylic acid) and were found to have an excellent fluorescence quenching effect (>400-fold) on common fluorophores (FAM, TMR, and Cy5) together with high stability under physiological conditions. As a proof of concept, the feasibility of these qPNPs for fluorescence sensing was validated by successful construction of two nanosensors (_FAMDEVD@qPNP and _Cy5SurC@qPNP), which could be used as promising nanosensors for live-cell imaging of the apoptosis-related protease caspase-3 and cancer-related survivin mRNA, respectively. As expected, in the FAM channel, the _FAMDEVD@qPNP showed fast and selective fluorescence responses toward caspase-3 in buffers and could be used to image the activation of drug-induced endogenous caspase-3. In the Cy5 channel, the _Cy5SurC@qPNP could be used to distinguish normal cells (MCF10A) from cancer cells (HeLa) by quantitatively detecting the endogenous survivin mRNA level. It could be further used to monitor changes in the endogenous survivin mRNA expression levels in drug-treated HeLa cells. Altogether, by virtue of their high quencher loading and broad-spectrum quenching efficiency and good signal-to-background ratio, these qPNPs might be particularly attractive alternatives to other conventional nanoquenchers for the construction of more complex biosensors in the future.

DNA interfaces with dimensional materials for biomedical applications

DNA interfaces with nano, micro, and macro materials have gained widespread attention for various applications. Such interfaces exhibit distinct functions and properties not only due to the unique properties of interfacing materials but also sequence- and conformation-dependent characteristics of the DNA. Therefore, DNA interfaces with diverse dimensional materials have advanced our understanding of the interaction mechanisms and the properties of such interfaces. The unique interfacial properties of such novel materials have applications in nanotechnology, biophysics, cell biology, biosensing, and bioelectronics. The field is growing rapidly with the frequent emergence of new interfaces carrying remarkable interfacial character. In this review article, we have classified the DNA interfaces into 0D, 1D, 2D, and 3D categories based on the types of dimensional materials. We review the key efforts made in the last five years and focus on types of interfaces, interfacing mechanisms, and their state-of-the-art applications. This review will draw a general interest because of the diversity in the DNA materials science but also the unique applications that will play a cutting-edge role in biomedical and biosensing research.

Flavonoid-Coated Gold Nanoparticles as Efficient Antibiotics against Gram-Negative Bacteria-Evidence from In Silico-Supported In Vitro Studies

Flavonoids are a class of bioactive plant-derived natural products that exhibit a broad range of biological activities, including antibacterial ones. Their inhibitory activity toward Gram-positive bacterial was found to be superior to that against Gram-negative ones. In the present study, a number of flavonoid-coated gold nanoparticles (GNPs) were designed to enhance the antibacterial effects of chrysin, kaempferol, and quercetin against a number of Gram-negative bacteria. The prepared GNPs were able to conjugate to these three flavonoids with conjugation efficiency ranging from 41% to 80%. Additionally, they were able to exert an enhanced antibacterial activity in comparison with the free flavonoids and the unconjugated GNPs. Quercetin-coated GNPs were the most active nano-conjugates and were able to penetrate the cell wall of E. coli. A number of in silico experiments were carried out to explain the conjugation efficiency and the antibacterial mechanisms of these flavonoids as follows: (i) these flavonoids can efficiently bind to the glutathione linker on the surface of GNPs via H-bonding; (ii) these flavonoids, particularly quercetin, were able to increase the bacterial membrane rigidity, and hence decrease its functionality; (iii) these flavonoids can inhibit E. coli's DNA gyrase (Gyr-B) with IC50 values ranging from 0.9 to 3.9 µM. In conclusion, these bioactive flavonoid-based GNPs are considered to be very promising antibiotic candidates for further development and evaluation.

Lipid Nanoparticle Spherical Nucleic Acids for Intracellular DNA and RNA Delivery

Lipid nanoparticle SNAs (LNP-SNAs) have been synthesized for the delivery of DNA and RNA to targets in the cytoplasm of cells. Both the composition of the LNP core and surface-presented DNA sequences contribute to LNP-SNA activity. G-rich sequences enhance the activity of LNP-SNAs compared to T-rich sequences. In the LNP core, increased cholesterol content leads to greater activity. Optimized LNP-SNA candidates reduce the siRNA concentration required to silence mRNA by 2 orders of magnitude compared to liposome-based SNAs. In addition, the LNP-SNA architectures alter biodistribution and efficacy profiles in mice. For example, mRNA within LNP-SNAs injected intravenously is primarily expressed in the spleen, while mRNA encapsulated by LNPs (no DNA on the surface) was expressed primarily in the liver with a relatively small amount in the spleen. These data show that the activity and biodistribution of LNP-SNA architectures are different from those of conventional liposomal SNAs and therefore potentially can be used to target tissues.

Near-Infrared Small Molecule as a Specific Fluorescent Probe for Ultrasensitive Recognition of Antiparallel Human Telomere G-Quadruplexes

In the past 10 years, many fluorescent probes have been developed to recognize G-quadruplexes (G4s) since G4s play an important role in biological systems. However, the selectivity and sensitivity of existing probes for G4s limit their further applications. Herein, we design and synthesize a new probe (TOVJ) by introducing 9-vinyljulolidine into TO. The new probe exhibits almost no fluorescence in an aqueous solution. Upon interacting with G4s, especially the antiparallel G4s, the fluorescence intensity was greatly enhanced (maximum 2742-fold) with a large Stokes shift of 198 nm and the maximum emission peak at 694 nm (near-infrared region). TOVJ showed high sensitivity and selectivity to G4s over other DNA topologies (ssDNA/dsDNA), especially to antiparallel G4s. For antiparallel human telomere G4 detection, the limits of detection of Hum24 and 22AG Na⁺ were as low as 164 and 231 pM, respectively. This indicates that TOVJ is a highly sensitive fluorescence sensor that can be effectively used for antiparallel human telomere G4 detection. The result of live-cell imaging showed that TOVJ could enter live cells and locate in the mitochondria.

Surface engineering strategies of gold nanomaterials and their applications in biomedicine and detection

Gold nanomaterials have potential applications in biosensors and biomedicine due to their controllable synthesis steps, high biocompatibility, low toxicity and easy surface modification. However, there are still various limitations including low water solubility and stability, which greatly affect their applications. In addition, some synthetic methods are very complicated and costly. Therefore, huge efforts have been made to improve their properties. This review mainly introduces the strategies for surface modification of gold nanomaterials, such as amines, biological small molecules and organic small molecules as well as the biological applications of these functionalized AuNPs. We aim to provide effective ideas for better functionalization of gold nanomaterials in the future.

Sialidase-Conjugated "NanoNiche" for Efficient Immune Checkpoint Blockade Therapy

Reactivation of T-cell immunity by blocking the PD-1/PD-L1 immune checkpoint has been considered a promising strategy for cancer treatment. However, the recognition of PD-L1 by antibodies is usually suppressed due to the N-linked glycosylation of PD-L1. In this study, we present an effective PD-L1-blocking strategy based on a sialidase-conjugated "NanoNiche" to improve the antitumor effect via T-cell reactivation. Molecularly imprinted by PD-L1 N-glycans, NanoNiche can specifically recognize glycosylated PD-L1 on the tumor cell surface, thereby resulting in more efficient PD-L1 blockade. Moreover, sialidase modified on the surface of NanoNiche can selectively strip sialoglycans from tumor cells, enhancing immune cell infiltration. In vitro studies confirmed that NanoNiche can specifically bind with PD-L1 while also desialylate the tumor cell surface. The proliferation of PD-L1-positive MDA-MB-231 human breast cancer cells under T-cell killing was significantly inhibited after NanoNiche treatment. In vivo experiments in solid tumors show enhanced therapeutic efficacy. Thus, the NanoNiche-sialidase conjugate represents a promising approach for immune checkpoint blockade therapy.

A first-in-human phase 0 clinical study of RNA interference-based spherical nucleic acids in patients with recurrent glioblastoma

Glioblastoma (GBM) is one of the most difficult cancers to effectively treat, in part because of the lack of precision therapies and limited therapeutic access to intracranial tumor sites due to the presence of the blood-brain and blood-tumor barriers. We have developed a precision medicine approach for GBM treatment that involves the use of brain-penetrant RNA interference-based spherical nucleic acids (SNAs), which consist of gold nanoparticle cores covalently conjugated with radially oriented and densely packed small interfering RNA (siRNA) oligonucleotides. On the basis of previous preclinical evaluation, we conducted toxicology and toxicokinetic studies in nonhuman primates and a single-arm, open-label phase 0 first-in-human trial (NCT03020017) to determine safety, pharmacokinetics, intratumoral accumulation and gene-suppressive activity of systemically administered SNAs carrying siRNA specific for the GBM oncogene Bcl2Like12 (Bcl2L12). Patients with recurrent GBM were treated with intravenous administration of siBcl2L12-SNAs (drug moniker: NU-0129), at a dose corresponding to 1/50th of the no-observed-adverse-event level, followed by tumor resection. Safety assessment revealed no grade 4 or 5 treatment-related toxicities. Inductively coupled plasma mass spectrometry, x-ray fluorescence microscopy, and silver staining of resected GBM tissue demonstrated that intravenously administered SNAs reached patient tumors, with gold enrichment observed in the tumor-associated endothelium, macrophages, and tumor cells. NU-0129 uptake into glioma cells correlated with a reduction in tumor-associated Bcl2L12 protein expression, as indicated by comparison of matched primary tumor and NU-0129-treated recurrent tumor. Our results establish SNA nanoconjugates as a potential brain-penetrant precision medicine approach for the systemic treatment of GBM.

Lactoferrin-Bearing Gold Nanocages for Gene Delivery in Prostate Cancer Cells in vitro

BACKGROUND

Gold nanocages have been widely used as multifunctional platforms for drug and gene delivery, as well as photothermal agents for cancer therapy. However, their potential as gene delivery systems for cancer treatment has been reported in combination with chemotherapeutics and photothermal therapy, but not in isolation so far. The purpose of this work was to investigate whether the conjugation of gold nanocages with the cancer targeting ligand lactoferrin, polyethylene glycol and polyethylenimine could lead to enhanced transfection efficiency on prostate cancer cells in vitro, without assistance of external stimulation.

METHODS

Novel lactoferrin-bearing gold nanocages conjugated to polyethylenimine and polyethylene glycol have been synthesized and characterized. Their transfection efficacy and cytotoxicity were assessed on PC-3 prostate cancer cell line following complexation with a plasmid DNA.

RESULTS

Lactoferrin-bearing gold nanocages, alone or conjugated with polyethylenimine and polyethylene glycol, were able to condense DNA at conjugate:DNA weight ratios 5:1 and higher. Among all gold conjugates, the highest gene expression was obtained following treatment with gold complex conjugated with polyethylenimine and lactoferrin, at weight ratio 40:1, which was 1.71-fold higher than with polyethylenimine. This might be due to the increased DNA cellular uptake observed with this conjugate, by up to 8.65-fold in comparison with naked DNA.

CONCLUSION

Lactoferrin-bearing gold nanocages conjugates are highly promising gene delivery systems to prostate cancer cells.

Stimuli Responsive, Programmable DNA Nanodevices for Biomedical Applications

Of the multiple areas of applications of DNA nanotechnology, stimuli-responsive nanodevices have emerged as an elite branch of research owing to the advantages of molecular programmability of DNA structures and stimuli-responsiveness of motifs and DNA itself. These classes of devices present multiples areas to explore for basic and applied science using dynamic DNA nanotechnology. Herein, we take the stake in the recent progress of this fast-growing sub-area of DNA nanotechnology. We discuss different stimuli, motifs, scaffolds, and mechanisms of stimuli-responsive behaviours of DNA nanodevices with appropriate examples. Similarly, we present a multitude of biological applications that have been explored using DNA nanodevices, such as biosensing, in vivo pH-mapping, drug delivery, and therapy. We conclude by discussing the challenges and opportunities as well as future prospects of this emerging research area within DNA nanotechnology.

Profiling and Regulating Proteins That Adsorb to DNA Materials in Human Serum

DNA aptamers and framework DNA nanostructures are emerging DNA materials with many appealing biological applications including biosensing, bioimaging, drug delivery, and so forth. When placed in physiological fluids, they inevitably encounter biomolecules (majorly proteins) and form complexes that largely affect their biological fate. Nevertheless, little is known regarding the quantitative profile of proteins that adsorb to DNA aptamers and DNA nanostructures in biological environments, and there are no potent strategies to regulate protein profiles. Herein, we performed a proteomic analysis to profile proteins that bind to DNA aptamers (Sgc8c and SYLC3) and nanostructures (a tetrahedral DNA nanostructure and a DNA origami rod) in human serum using liquid chromatography-mass spectrometry (LC-MS). Dozens to hundreds of proteins were identified with each DNA material exhibiting highly distinctive profiles. It was also revealed that the origin of serum (from healthy donor vs from prostate cancer patients) causes significant differences in profiles of bound proteins. Furthermore, we demonstrated that the protein profile may be regulated by tethering a layer of single-stranded DNA (polythymine) onto the DNA origami rod to alleviate the adsorption of complement-associated proteins, which significantly reduced its sequestration by macrophages. Taken together, this study has provided qualitative and quantitative proteomic profiles regarding serum proteins that adsorb to various DNA materials and have demonstrated that the composition of interacted proteins may be regulated toward better biological performances.

Charge-Conversion Strategies for Nucleic Acid Delivery

Nucleic acids are now considered as one of the most potent therapeutic modalities, as their roles go beyond storing genetic information and chemical energy or as signal transducer. Attenuation or expression of desired genes through nucleic acids have profound implications in gene therapy, gene editing and even in vaccine development for immunomodulation. Although nucleic acid therapeutics bring in overwhelming possibilities towards the development of molecular medicines, there are significant loopholes in designing and effective translation of these drugs into the clinic. One of the major pitfalls lies in the traditional design concepts for nucleic acid drug carriers, viz. cationic charge induced cytotoxicity in delivery pathway. Targeting this bottleneck, several pioneering research efforts have been devoted to design innovative carriers through charge-conversion approaches, whereby built-in functionalities convert from cationic to neutral or anionic, or even from anionic to cationic enabling the carrier to overcome several critical barriers for therapeutics delivery, such as serum deactivation, instability in circulation, low transfection and poor endosomal escape. This review will critically analyze various molecular designs of charge-converting nanocarriers in a classified approach for the successful delivery of nucleic acids. Accompanied by the narrative on recent clinical nucleic acid candidates, the review concludes with a discussion on the pitfalls and scope of these interesting approaches.