Highly Photoluminescent Nitrogen- and Zinc-Doped Carbon Dots for Efficient Delivery of CRISPR/Cas9 and mRNA

Nucleic acid-responsive smart systems for controlled cargo delivery

Stimulus-responsive delivery systems allow controlled, highly regulated, and efficient delivery of various cargos while minimizing side effects. Owing to the unique properties of nucleic acids, including the ability to adopt complex structures by base pairing, their easy synthesis, high specificity, shape memory, and configurability, they have been employed in autonomous molecular motors, logic circuits, reconfigurable nanoplatforms, and catalytic amplifiers. Moreover, the development of nucleic acid (NA)-responsive intelligent delivery vehicles is a rapidly growing field. These vehicles have attracted much attention in recent years due to their programmable, controllable, and reversible properties. In this work, we review several types of NA-responsive controlled delivery vehicles based on locks and keys, including DNA/RNA-responsive, aptamer-responsive, and CRISPR-responsive, and summarize their advantages and limitations.

Gene Transfection Efficiency Improvement with Lipid Conjugated Cationic Carbon Dots

An ideal vehicle with a high transfection efficiency is crucial for gene delivery. In this study, a type of cationic carbon dot (CCD) known as APCDs were first prepared with arginine (Arg) and pentaethylenehexamine (PEHA) as precursors and conjugated with oleic acid (OA) for gene delivery. By tuning the mass ratio of APCDs to OA, APCDs-OA conjugates, namely, APCDs-0.5OA, APCDs-1.0OA, and APCDs-1.5OA were synthesized. All three amphiphilic APCDs-OA conjugates show high affinity to DNA through electrostatic interactions. APCDs-0.5OA exhibit strong binding with small interfering RNA (siRNA). After being internalized by Human Embryonic Kidney (HEK 293) and osteosarcoma (U2OS) cells, they could distribute in both the cytoplasm and the nucleus. With APCDs-OA conjugates as gene delivery vehicles, plasmid DNA (pDNA) that encodes the gene for the green fluorescence protein (GFP) can be successfully delivered in both HEK 293 and U2OS cells. The GFP expression levels mediated by APCDs-0.5OA and APCDs-1.0OA are ten times greater than that of PEI in HEK 293 cells. Furthermore, APCDs-0.5OA show prominent siRNA transfection efficiency, which is proven by the significantly downregulated expression of FANCA and FANCD2 proteins upon delivery of FANCA siRNA and FANCD2 siRNA into U2OS cells. In conclusion, our work demonstrates that conjugation of CCDs with a lipid structure such as OA significantly improves the gene transfection efficiency, providing a new idea about the designation of nonviral carriers in gene delivery systems.

Carbon-Based Nanostructures as Emerging Materials for Gene Delivery Applications

Gene therapeutics are promising for treating diseases at the genetic level, with some already validated for clinical use. Recently, nanostructures have emerged for the targeted delivery of genetic material. Nanomaterials, exhibiting advantageous properties such as a high surface-to-volume ratio, biocompatibility, facile functionalization, substantial loading capacity, and tunable physicochemical characteristics, are recognized as non-viral vectors in gene therapy applications. Despite progress, current non-viral vectors exhibit notably low gene delivery efficiency. Progress in nanotechnology is essential to overcome extracellular and intracellular barriers in gene delivery. Specific nanostructures such as carbon nanotubes (CNTs), carbon quantum dots (CQDs), nanodiamonds (NDs), and similar carbon-based structures can accommodate diverse genetic materials such as plasmid DNA (pDNA), messenger RNA (mRNA), small interference RNA (siRNA), micro RNA (miRNA), and antisense oligonucleotides (AONs). To address challenges such as high toxicity and low transfection efficiency, advancements in the features of carbon-based nanostructures (CBNs) are imperative. This overview delves into three types of CBNs employed as vectors in drug/gene delivery systems, encompassing their synthesis methods, properties, and biomedical applications. Ultimately, we present insights into the opportunities and challenges within the captivating realm of gene delivery using CBNs.

Novel Vectors and Administrations for mRNA Delivery

mRNA therapy has shown great potential in infectious disease vaccines, cancer immunotherapy, protein replacement therapy, gene editing, and other fields due to its central role in all life processes. However, mRNA is challenging to pass through the cell membrane due to its significant negative charges and degradation from RNase, so the key to mRNA therapy is efficient packaging and delivery of it with appropriate vectors. Presently researchers have developed various vectors such as viruses and liposomes, but these conventional vectors are now difficult to meet the growing requirement like safety, efficiency, and targeting, so many novel delivery vectors with unique advantages have emerged recently. This review mainly introduces two categories of novel vectors: biomacromolecules and inorganic nanoparticles, as well as two novel methods of control and administration based on these novel vectors: controlled-release administration and non-invasive administration. These novel delivery strategies have the advantages of high safety, biocompatibility, versatility, intelligence, and targeting. This paper analyzes the challenges faced by the field of mRNA delivery in depth, and discusses how to use the characteristics of novel vectors and administrations to solve these problems.

Recent Advancements in Metal and Non-Metal Mixed-Doped Carbon Quantum Dots: Synthesis and Emerging Potential Applications

In nanotechnology, the synthesis of carbon quantum dots (CQDs) by mixed doping with metals and non-metals has emerged as an appealing path of investigation. This review offers comprehensive insights into the synthesis, properties, and emerging applications of mixed-doped CQDs, underlining their potential for revolutionary advancements in chemical sensing, biosensing, bioimaging, and, thereby, contributing to advancements in diagnostics, therapeutics, and the under standing of complex biological processes. This synergistic combination enhances their sensitivity and selectivity towards specific chemical analytes. The resulting CQDs exhibit remarkable fluorescence properties that can be involved in precise chemical sensing applications. These metal-modified CQDs show their ability in the selective and sensitive detection from Hg to Fe and Mn ions. By influencing their exceptional fluorescence properties, they enable precise detection and monitoring of biomolecules, such as uric acid, cholesterol, and many antibiotics. Moreover, when it comes to bioimaging, these doped CQDs show unique behavior towards detecting cell lines. Their ability to emit light across a wide spectrum enables high-resolution imaging with minimal background noise. We uncover their potential in visualizing different cancer cell lines, offering valuable insights into cancer research and diagnostics. In conclusion, the synthesis of mixed-doped CQDs opens the way for revolutionary advancements in chemical sensing, biosensing, and bioimaging. As we investigate deeper into this field, we unlock new possibilities for diagnostics, therapeutics, and understanding complex biological processes.

Supramolecular Chemistry of Carbon-Based Dots Offers Widespread Opportunities

Carbon dots are an emerging class of nanomaterials that has recently attracted considerable attention for applications that span from biomedicine to energy. These photoluminescent carbon nanoparticles are defined by characteristic sizes of <10 nm, a carbon-based core and various functional groups at their surface. Although the surface groups are widely used to establish non-covalent bonds (through electrostatic interactions, coordinative bonds, and hydrogen bonds) with various other (bio)molecules and polymers, the carbonaceous core could also establish non-covalent bonds (ππ stacking or hydrophobic interactions) with π-extended or apolar compounds. The surface functional groups, in addition, can be modified by various post-synthetic chemical procedures to fine-tune the supramolecular interactions. Our contribution categorizes and analyzes the interactions that are commonly used to engineer carbon dots-based materials and discusses how they have allowed preparation of functional assemblies and architectures used for sensing, (bio)imaging, therapeutic applications, catalysis, and devices. Using non-covalent interactions as a bottom-up approach to prepare carbon dots-based assemblies and composites can exploit the unique features of supramolecular chemistry, which include adaptability, tunability, and stimuli-responsiveness due to the dynamic nature of the non-covalent interactions. It is expected that focusing on the various supramolecular possibilities will influence the future development of this class of nanomaterials.

N,Zn-Doped Fluorescent Sensor Based on Carbon Dots for the Subnanomolar Detection of Soluble Cr(VI) Ions

The development of a fluorescent sensor has attracted much attention for the detection of various toxic pollutants in the environment. In this work, fluorescent carbon dots (N,Zn-CDs) doped with nitrogen and zinc were synthesized using citric acid monohydrate and 4-pyridinecarboxyaldehyde as carbon and nitrogen sources, respectively. The synthesized N,Zn-CDs served as an "off" fluorescence detector for the rapid and sensitive detection of hexavalent chromium ions (Cr(VI)). The zinc metal integrated into the heteroatomic fluorescent carbon dot played a functional role by creating a coordination site for the hydrogen ions that were displaced after the addition of Cr to the solution matrix. The stepwise addition of Cr(VI) effectively quenched the fluorescence intensity of the N,Zn-CDs, and this phenomenon was attributed to the internal filter effect. A low detection limit of 0.47 nmol/L for Cr(VI) was achieved in the fluorescence experiments. Real water samples were used to evaluate the practical application of N,Zn-CDs for the quantification of Cr(VI). The results show acceptable recoveries and agreement with ion chromatography-ultraviolet spectrometry results. These good recoveries indicate that the fluorescence probe is very well suited for environmental measurements.

Could artificial intelligence revolutionize the development of nanovectors for gene therapy and mRNA vaccines?

Gene therapy enables the introduction of nucleic acids like DNA and RNA into host cells, and is expected to revolutionize the treatment of a wide range of diseases. This growth has been further accelerated by the discovery of CRISPR/Cas technology, which allows accurate genomic editing in a broad range of cells and organisms in vitro and in vivo. Despite many advances in gene delivery and the development of various viral and non-viral gene delivery vectors, the lack of highly efficient non-viral systems with low cellular toxicity remains a challenge. The application of cutting-edge technologies such as artificial intelligence (AI) has great potential to find new paradigms to solve this issue. Herein, we review AI and its major subfields including machine learning (ML), neural networks (NNs), expert systems, deep learning (DL), computer vision and robotics. We discuss the potential of AI-based models and algorithms in the design of targeted gene delivery vehicles capable of crossing extracellular and intracellular barriers by viral mimicry strategies. We finally discuss the role of AI in improving the function of CRISPR/Cas systems, developing novel nanobots, and mRNA vaccine carriers.

The long road to bloom in conifers

More than 600 species of conifers (phylum Pinophyta) serve as the backbone of the Earth's terrestrial plant community and play key roles in global carbon and water cycles. Although coniferous forests account for a large fraction of global wood production, their productivity relies largely on the use of genetically improved seeds. However, acquisition of such seeds requires recurrent selection and testing of genetically superior parent trees, eventually followed by the establishment of a seed orchard to produce the improved seeds. The breeding cycle for obtaining the next generation of genetically improved seeds can be significantly lengthened when a target species has a long juvenile period. Therefore, development of methods for diminishing the juvenile phase is a cost-effective strategy for shortening breeding cycle in conifers. The molecular regulatory programs associated with the reproductive transition and annual reproductive cycle of conifers are modulated by environmental cues and endogenous developmental signals. Mounting evidence indicates that an increase in global average temperature seriously threatens plant productivity, but how conifers respond to the ever-changing natural environment has yet to be fully characterized. With the breakthrough of assembling and annotating the giant genome of conifers, identification of key components in the regulatory cascades that control the vegetative to reproductive transition is imminent. However, comparison of the signaling pathways that control the reproductive transition in conifers and the floral transition in Arabidopsis has revealed many differences. Therefore, a more complete understanding of the underlying regulatory mechanisms that control the conifer reproductive transition is of paramount importance. Here, we review our current understanding of the molecular basis for reproductive regulation, highlight recent discoveries, and review new approaches for molecular research on conifers.

Recent advances of metal-based nanoparticles in nucleic acid delivery for therapeutic applications

Recent efforts in designing nanomaterials to deliver potential therapeutics to the targeted site are overwhelming and palpable. Engineering nanomaterials to deliver biological molecules to exert desirable physiological changes, with minimized side effects and optimal dose, has revolutionized the next-generation therapy for several diseases. The rapid progress of nucleic acids as biopharmaceutics is going to alter the traditional pharmaceutics practices in modern medicine. However, enzymatic instability, large size, dense negative charge (hydrophilic for cell uptake), and unintentional adverse biological responses-such as prolongation of the blood coagulation and immune system activation-hamper the potential use of nucleic acids for therapeutic purposes. Moreover, the safe delivery of nucleic acids into the clinical setting is an uphill task, and several efforts are being put forward to deliver them to targeted cells. Advances in Metal-based NanoParticles (MNPs) are drawing attention due to the unique properties offered by them for drug delivery, such as large surface-area-to-volume ratio for surface modification, increased therapeutic index of drugs through site-specific delivery, increased stability, enhanced half-life of the drug in circulation, and efficient biodistribution to the desired targeted site. Here, the potential of nanoparticles delivery systems for the delivery of nucleic acids, specially MNPs, and their ability and advantages over other nano delivery systems are reviewed.

Generating Human Induced Pluripotent Stem Cell Via Low-Dose Polyethylenimine-Mediated Transfection: An Optimized Protocol

Human dermal fibroblasts (HDFs) can be reprogrammed through different strategies to generate human induced pluripotent stem cells (hiPSCs). However, most of these strategies require high-cost materials and specific equipment not readily accessible in most laboratories. Hence, liposomal and virus-based techniques can replace with polyethylenimine (PEI)-mediated transfection to overcome these challenges. However, few researchers have addressed the PEI's ability to transfect HDFs. This study used PEI reagent to transfer oriP/EBNA1-based vector into HDFs to produce hiPSC lines. We first described conditions allowing the efficient transfection of HDFs with low cytotoxicity and without specific types of equipment and optimized several parameters relevant to the transfection procedure. We then monitored the effect of different N/P ratios on transfection efficiency and cytotoxicity using flow cytometry and fluorescent microscopy. By the results, we found that transfection efficiency was greatly affected by plasmid DNA concentration, PEI concentration, order of combining reagents, serum presence in polyplexes, and the duration of serum starvations. Moreover, using the optimized condition, we found that the N/P ratio of 3 achieved the highest percentage of HDFs positive for green fluorescent protein plasmid (∼40%) with minimal cell toxicity. We finally generated hiPSCs using the optimized protocol and oriP/EBNA1-based vectors. We confirmed hiPSC formation by characterizing tests: alkaline phosphatase staining, immunocytochemistry assay, real-time PCR analysis, in vitro differentiation into three germ layers, and karyotyping test. In conclusion, our results indicated that 25 kDa branched PEI could efficiently transfect HDFs toward generating hiPSCs via a simple, cost-effective, and optimized condition.

Carrier strategies boost the application of CRISPR/Cas system in gene therapy

Emerging clustered regularly interspaced short palindromic repeat/associated protein (CRISPR/Cas) genome editing technology shows great potential in gene therapy. However, proteins and nucleic acids suffer from enzymatic degradation in the physiological environment and low permeability into cells. Exploiting carriers to protect the CRISPR system from degradation, enhance its targeting of specific tissues and cells, and reduce its immunogenicity is essential to stimulate its clinical applications. Here, the authors review the state-of-the-art CRISPR delivery systems and their applications, and describe strategies to improve the safety and efficacy of CRISPR mediated genome editing, categorized by three types of cargo formats, that is, Cas: single-guide RNA ribonucleoprotein, Cas mRNA and single-guide RNA, and Cas plasmid expressing CRISPR/Cas systems. The authors hope this review will help develop safe and efficient nanomaterial-based carriers for CRISPR tools.

Smart Strategies for Precise Delivery of CRISPR/Cas9 in Genome Editing

The emergence of CRISPR/Cas technology has enabled scientists to precisely edit genomic DNA sequences. This approach can be used to modulate gene expression for the treatment of genetic disorders and incurable diseases such as cancer. This potent genome-editing tool is based on a single guide RNA (sgRNA) strand that recognizes the targeted DNA, plus a Cas nuclease protein for binding and processing the target. CRISPR/Cas has great potential for editing many genes in different types of cells and organisms both in vitro and in vivo. Despite these remarkable advances, the risk of off-target effects has hindered the translation of CRISPR/Cas technology into clinical applications. To overcome this hurdle, researchers have devised gene regulatory systems that can be controlled in a spatiotemporal manner, by designing special sgRNA, Cas, and CRISPR/Cas delivery vehicles that are responsive to different stimuli, such as temperature, light, magnetic fields, ultrasound (US), pH, redox, and enzymatic activity. These systems can even respond to dual or multiple stimuli simultaneously, thereby providing superior spatial and temporal control over CRISPR/Cas gene editing. Herein, we summarize the latest advances on smart sgRNA, Cas, and CRISPR/Cas nanocarriers, categorized according to their stimulus type (physical, chemical, or biological).

Non-viral delivery of the CRISPR/Cas system: DNA versus RNA versus RNP

Since its discovery, the CRISPR/Cas technology has rapidly become an essential tool in modern biomedical research. The opportunities to specifically modify and correct genomic DNA has also raised big hope...

Smart arginine-equipped polycationic nanoparticles for p/CRISPR delivery into cells

An efficient and safe delivery system for the transfection of CRISPR plasmid (p/CRISPR) into target cells can open new avenues for the treatment of various diseases. Herein, we design a novel nonvehicle by integrating an arginine-disulfide linker with low-molecular-weight PEI (PEI_1.8k) for the delivery of p/CRISPR. These PEI_1.8k-Arg nanoparticles facilitate the plasmid release and improve both membrane permeability and nuclear localization, thereby exhibiting higher transfection efficiency compared to native PEI_1.8kin the delivery of nanocomplexes composed of PEI_1.8k-Arg and p/CRISPR into conventional cells (HEK 293T). This nanovehicle is also able to transfect p/CRISPR in a wide variety of cells, including hard-to-transfect primary cells (HUVECs), cancer cells (HeLa), and neuronal cells (PC-12) with nearly 5-10 times higher efficiency compared to the polymeric gold standard transfection agent. Furthermore, the PEI_1.8k-Arg nanoparticles can edit the GFP gene in the HEK 293T-GFP reporter cell line by delivering all possible forms of CRISPR/Cas9 system (e.g. plasmid encoding Cas9 and sgRNA targeting GFP, and Cas9/sgRNA ribonucleoproteins (RNPs) as well as Cas9 expression plasmid andin vitro-prepared sgRNA) into HEK 293T-GFP cells. The successful delivery of p/CRISPR into local brain tissue is also another remarkable capability of these nanoparticles. In view of all the exceptional benefits of this safe nanocarrier, it is expected to break new ground in the field of gene editing, particularly for therapeutic purposes.