Polycations-functionalized water-soluble gold nanoclusters: a potential platform for simultaneous enhanced gene delivery and cell imaging

Enhancing the Green Synthesis of Glycerol Carbonate: Carboxylation of Glycerol with CO2 Catalyzed by Metal Nanoparticles Encapsulated in Cerium Metal-Organic Frameworks

The reaction of glycerol with CO2 to produce glycerol carbonate was performed successfully in the presence of gold nanoparticles (AuNPs) supported by a metal-organic framework (MOF) constructed from mixed carboxylate (terephthalic acid and 1,3,5-benzenetricarboxylic acid). The most efficient were two AuNPs@MOF catalysts prepared from pre-synthesized MOF impregnated with Au3+ salt and subsequently reduced to AuNPs using H2 (catalyst 4%Au(H2)@MOF1) or reduced with NaBH4 (catalyst 4%Au@PEI-MOF1). Compared to existing catalysts, AuNPs@MOFs require simple preparation and operate under mild and sustainable conditions, i.e., a much lower temperature and the lowest CO2 overpressure ever reported, with MgCO3 having been found to be the optimal dehydrating agent. Although the yield of the process is still not competitive with previously developed systems, the most promising advantage is the highest TOF (78 h-1) ever reported for this reaction. The optimal parameters observed for AuNPs were also tested on AgNPs and CuNPs with promising results, suggesting their great potential for industrial application. The catalysts were characterized by XRD, TEM, SEM-EDS, ICP-MS, XPS, and porosity measurements, confirming that AuNPs are present in low concentration, uniformly distributed, and confined to the cavities of the MOF.

Determination of trypsin using protamine mediated fluorescent enhancement of DNA templated Au nanoclusters

A fluorescent method is described for trypsin determination through the strong electrostatic interactions between cationic polyelectrolytes and single-stranded DNA (ssDNA) templated Au nanoclusters (AuNCs). The ssDNA-AuNCs display improved fluorescence emission with excitation/emission maxima at 280/475 nm after being incorporated with poly(diallyldimethylammonium chloride) (PDDA). Fluorescent enhancement is mainly attributed to the electrostatic interactions occurring  between PDDA and ssDNA templates. This can make the conformation of the ssDNA templates to change. Thus, it offers a better microenvironment for stabilizing and protecting ssDNA-AuNCs, and results in fluorescence emission enhancement. By using protamine as a model, the method is employed for the determination of trypsin. The assay enables trypsin to be determined with good sensitivity and a linear response ranging from 5 ng⋅mL^-1 to 60 ng⋅mL^-1 with a 1.5 ng⋅mL^-1 limit of detection. It is also extended to determine  the trypsin contents in human's serum samples with recoveries between 98.7% and 103.5% with relative standard deviations (RSDs) between 3.5% and 4.8%. A novel fluorescent strategy has been developed for of trypsin determination by using protamine mediated fluorescent enhancement of DNA templated Au nanoclusters.

Polyethyleneimine/polyethylene glycol-conjugated gold nanoparticles as nanoscale positive/negative controls in nanotoxicology: testing in frog embryo teratogenesis assay-Xenopus and mammalian tissue culture system

Despite the great potential of using positively charged gold nanoparticles (AuNPs) in nanomedicine, no systematic studies have been reported on their synthesis optimization or colloidal stability under physiological conditions until a group at the National Institute of Standards and Technology recently succeeded in producing remarkably stable polyethyleneimine (PEI)-coated AuNPs (Au-PEI). This improved version of Au-PEI (Au-PEI25kB) has increased the demand for toxicity and teratogenicity information for applications in nanomedicine and nanotoxicology. In vitro assays for Au-PEI25kB in various cell lines showed substantial active cytotoxicity. For advanced toxicity research, the frog embryo teratogenesis assay-Xenopus (FETAX) method was employed in this study. We observed that positively-charged Au-PEI25kB exhibited significant toxicity and teratogenicity, whereas polyethylene glycol conjugated AuNPs (Au-PEG) used as comparable negative controls did not. There is a characteristic avidity of Au-PEI25kB for the jelly coat, the chorionic envelope (also known as vitelline membrane) and the cytoplasmic membrane, as well as a barrier effect of the chorionic envelope observed with Au-PEG. To circumvent these characteristics, an injection-mediated FETAX approach was utilized. Like treatment with the FETAX method, the injection of Au-PEI25kB severely impaired embryo development. Notably, the survival/concentration curve that was steep when the standard FETAX approach was employed became gradual in the injection-mediated FETAX. These results suggest that Au-PEI25kB may be a good candidate as a nanoscale positive control material for nanoparticle analysis in toxicology and teratology.

Viewing Aggregation-Induced Emission of Metal Nanoclusters from Design Strategies to Applications

Aggregation-induced emission (AIE)-type metal nanoclusters (NCs) represent an innovative type of luminescent metal NCs whose aggregates exhibit superior performance over that of individuals, attracting wide attention over the past decade. Here, we give a concise overview of the progress made in this area, from design strategies to applications. The representative design strategies, including solvent-induction, cation-induction, crystallization-induction, pH-induction, ligand inheritance, surface constraint, and minerals- and MOF-confinement, are first discussed. We then present the typical practical applications of AIE-type metal NCs in the various sectors of bioimaging, biological diagnosis and therapy (e.g., antibacterial agents, cancer radiotherapy), light-emitting diodes (LEDs), detection assays, and circularly polarized luminescence (CPL). To this end, we present our viewpoints on the promises and challenges of AIE-type metal NCs, which may shed light on the design of highly luminescent metal NCs, stimulating new vitality and serving as a continuous boom for the metal NC community in the future.

One-Step Synthesis of Peptide-Gold Nanoclusters with Tunable Fluorescence and Enhanced Gene Delivery Efficiency

In this study, peptide-gold nanoclusters with tunable fluorescence were prepared by a simple "one-pot" method, which were used for gene localization and delivery in vivo to achieve efficient intracellular colocalization, uptake, and transfection. The efficiency of pDNA transfection was up to 70.6%, and there was no obvious cytotoxicity. This study proves that the simple-composition and bio-friendly peptide-gold nanoclusters are promising gene delivery carriers and can provide a powerful theoretical and experimental basis for the application of peptide-metal nanocomplexes in gene delivery and other biomedicine fields.

High Stability Au NPs: From Design to Application in Nanomedicine

In recent years, Au-based nanomaterials are widely used in nanomedicine and biosensors due to their excellent physical and chemical properties. However, these applications require Au NPs to have excellent stability in different environments, such as extreme pH, high temperature, high concentration ions, and various biomatrix. To meet the requirement of multiple applications, many synthetic substances and natural products are used to prepare highly stable Au NPs. Because of this, we aim at offering an update comprehensive summary of preparation high stability Au NPs. In addition, we discuss its application in nanomedicine. The contents of this review are based on a balanced combination of our studies and selected research studies done by worldwide academic groups. First, we address some critical methods for preparing highly stable Au NPs using polymers, including heterocyclic substances, polyethylene glycols, amines, and thiol, then pay attention to natural product progress Au NPs. Then, we sum up the stability of various Au NPs in different stored times, ions solution, pH, temperature, and biomatrix. Finally, the application of Au NPs in nanomedicine, such as drug delivery, bioimaging, photothermal therapy (PTT), clinical diagnosis, nanozyme, and radiotherapy (RT), was addressed concentratedly.

Gold nanoclusters: An ultrasmall platform for multifaceted applications

Gold nanoclusters (Au NCs) with a core size below 2 nm form an exciting class of functional nano-materials with characteristic physical and chemical properties. The properties of Au NCs are more prominent and extremely different from their bulk counterparts. The synthesis of Au NCs is generally assisted by template or ligand, which impart excellent cluster stability and high quantum yield. The tunable and sensitive physicochemical properties of Au NCs open horizons for their advanced applications in various interdisciplinary fields. In this review, we briefly summarize the solution phase synthesis and origin of the characteristic properties of Au NCs. A vast review of recent research work introducing biosensors based on Au NCs has been presented along with their specifications and detection limits. This review also highlights recent progress in the use of Au NCs as bio-imaging probe, enzyme mimic, temperature sensing probe and catalysts. A speculation on present challenges and certain future prospects have also been provided to enlighten the path for advancement of multifaceted applications of Au NCs.

Photoluminescent Nanomaterials for Medical Biotechnology

Creation of various photoluminescent nanomaterials has significantly expanded the arsenal of approaches used in modern biomedicine. Their unique photophysical properties can significantly improve the sensitivity and specificity of diagnostic methods, increase therapy effectiveness, and make a theranostic approach to treatment possible through the application of nanoparticle conjugates with functional macromolecules. The most widely used nanomaterials to date are semiconductor quantum dots; gold nanoclusters; carbon dots; nanodiamonds; semiconductor porous silicon; and up-conversion nanoparticles. This paper considers the promising groups of photoluminescent nanomaterials that can be used in medical biotechnology: in particular, for devising agents for optical diagnostic methods, sensorics, and various types of therapy.

Hierarchical Gold Mesoflowers in Enzyme Engineering: An Environmentally Friendly Strategy for the Enhanced Enzymatic Performance and Biodiesel Production

To expand the field of nanomaterial and engineering of enzyme in eco-friendly processes, gold mesoflower (Au-MF) nanostructure was applied for preparation of three series of immobilized lipase (Au-MF/SAM 1-3) through biofunctionalization of surface by Ugi multicomponent reaction. The synthesized Au-MF/SAM 1-3/lipase as unique biocatalysts was confirmed by different analytical tools and techniques. Compared to the free lipase, the Au-MF/SAM 1-3/lipase showed more stability at high temperature and pH. Also, these biocatalysts showed high storage stability and reusability after 2 months and eight cycles, respectively. Moreover, the kinetic behavior was investigated and the results showed a minimal impairment of catalytic activity of immobilized lipase. The kinetic constants of the immobilized lipase, Au-MF/SAM 2/lipase, are K_m = 0.37 mM, V_max = 0.22 mM min^-1, and k_cat = 154 min^-1. The immobilized lipase showed smaller activation energy (E_a) than that of free enzyme, indicating that the immobilized enzyme is less sensitive to temperature. In the following, the biodiesel production from palmitic acid was studied in the presence of Au-MF/SAM 2/lipase as an efficient biocatalyst. The influence of different reaction parameters such as temperature, molar ratio of alcohol to palmitic acid, water content, and lipase amount was deeply investigated.

Parallel Multiparameter Study of PEI-Functionalized Gold Nanoparticle Synthesis for Biomedical Applications: Part 2. Elucidating the Role of Surface Chemistry and Polymer Structure in Performance

Elucidating the polyethyleneimine (PEI) chemistry to predictively and reproducibly synthesize gold nanoparticle (AuNP)-PEI conjugates with desired properties has been elusive despite evaluation in numerous studies and reported enhanced properties. The lack of reproducible methods to control the core size and stability has led to contradictory results for performance and safety; thus, advancement of the conjugate platform for commercial use has likely been hindered. Recently, we reported a robust, reproducible method for synthesizing PEI-functionalized AuNPs (Au-PEIs), providing an opportunity to investigate structure-function relationships and to further investigate synthesis parameters affecting performance, where only materials stable in biological media are candidates for use. The properties of Au-PEIs prepared by the optimized reduction of HAuCl₄ using four different structural variants of PEI changed significantly with the PEI molar mass and backbone form (branched or linear). In the present study using our previously reported synthesis procedure, comprehensive analysis of properties such as size distribution, surface plasmon resonance (SPR), morphological state, surface functionality, and the shelf life has been systematically evaluated to elucidate the role of surface chemistry and reactive groups involved in conjugation, as a function of conjugate size and morphology. Being important for commercial adoption, the chemistry was related to the observed colloidal stability of the product in relevant media, including exposure to physiological variables such as salt, pH, proteins, and thermal changes. Overall, this work advances progress toward smart design of engineered nanoscale drug delivery systems and devices by providing unreported details of contributions affecting formation, stability, and fate.

Coassembly of nucleus-targeting gold nanoclusters with CRISPR/Cas9 for simultaneous bioimaging and therapeutic genome editing

The clustered regularly interspaced short palindromic repeats (CRISPR)/associated protein 9 (CRISPR/Cas9) technology enables genome editing with high precision and versatility and has been widely utilized to combat viruses, bacteria, cancers, and genetic diseases. Nonviral nanocarriers can overcome several limitations of viral vehicles, including immunogenicity, inflammation, carcinogenicity, and low versatility, and thus represent promising platforms for CRISPR/Cas9 delivery. Herein, we for the first time develop the application of protamine-capped gold nanoclusters (protamine-AuNCs) as an effective nanocarrier for Cas9-sgRNA plasmid transport and release to achieve efficient genome editing. The protamine-AuNCs integrate the merits of AuNCs and protamine: AuNCs are able to promptly assemble with Cas9-sgRNA plasmids to allow efficient cellular delivery, while the cationic protamine facilitates the effective release of Cas9-sgRNA plasmids into the cellular nucleus. The AuNCs/Cas9-gRNA plasmid nanocomplexes can not only achieve successful gene editing in cells but also knock out the oncogenic gene for cancer therapy. Moreover, the AuNCs with excellent photoluminescence characteristics endow our nanoplatform with the functionality of bioimaging. Overall, our study provides strong evidence that demonstrates protamine-AuNCs as an effective CRISPR/Cas9 delivery tool for gene therapy.

Emerging Concepts of Nanobiotechnology in mRNA Delivery

Introducing mRNA into cells has attracted intense interest for diverse applications; however, success requires delivery solutions. Engineered nanomaterials have been applied as mRNA nanocarriers; their functions are designed mainly as delivery vehicles, but rarely in regulation of the protein translation. Recently, progress in nanobiotechnology has shifted the design principle of mRNA nanocarriers from simple delivery tools to translation modulators. Here, we review the emerging concepts of nanomaterials regulating mRNA translation and recent progress in mRNA delivery. Designer nanomaterials providing integrated functions for specific mRNA applications are also reviewed to provide insights for the design of next-generation nanomaterials to revolutionize mRNA technology.

Therapeutic applications of CRISPR/Cas9 in breast cancer and delivery potential of gold nanomaterials

Globally, approximately 1 in 4 cancers in women are diagnosed as breast cancer (BC). Despite significant advances in the diagnosis and therapy BCs, many patients develop metastases or relapses. Hence, novel therapeutic strategies are required, that can selectively and efficiently kill malignant cells. Direct targeting of the genetic and epigenetic aberrations that occur in BC development is a promising strategy to overcome the limitations of current therapies, which target the tumour phenotype. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas system, composed of only an easily modifiable single guide RNA (sgRNA) sequence bound to a Cas9 nuclease, has revolutionised genome editing due to its simplicity and efficiency compared to earlier systems. CRISPR/Cas9 and its associated catalytically inactivated dCas9 variants facilitate the knockout of overexpressed genes, correction of mutations in inactivated genes, and reprogramming of the epigenetic landscape to impair BC growth. To achieve efficient genome editing in vivo, a vector is required to deliver the components to target cells. Gold nanomaterials, including gold nanoparticles and nanoclusters, display many advantageous characteristics that have facilitated their widespread use in theranostics, as delivery vehicles, and imaging and photothermal agents. This review highlights the therapeutic applications of CRISPR/Cas9 in treating BCs, and briefly describes gold nanomaterials and their potential in CRISPR/Cas9 delivery.

Biomaterials for Interfacing Cell Imaging and Drug Delivery: An Overview

This feature article provides an overview of different kinds of futuristic biomaterials which have the potential to be used for fluorescent imaging and drug delivery, often simultaneously. The synthesis route or preparation process, fluorescence property, release profile, biocompatibility, bioimaging, and mechanistic approaches are vividly discussed. These include bioimaging with fluorescently doped quantum dots, mesoporous silica, noble metals, metal clusters, hydrophilic/hydrophobic polymers, semiconducting polymer dots, carbon/graphene dots, dendrimers, fluorescent proteins, and other nanobiomaterials. Another section discusses the controlled and targeted drug, gene, or biologically active material delivery using various vehicles such as micelles, 2D nanomaterials, organic nanoparticles, polymeric nanohybrids, and chemically modified polymers. In the last section, we discuss biomaterials, which can deliver biologically active molecules, and imaging the cell/tissue.

Biomedical Applications for Gold Nanoclusters: Recent Developments and Future Perspectives

Gold nanoclusters (AuNCs) have been extensively applied as a fluorescent probe for biomedical applications in imaging, detection, and therapy due to their unique chemical and physical properties. Fluorescent probes of AuNCs have exhibited high compatibility, superior photostablility, and excellent water solubility which resulted in remarkable biomedical applications for long-term imaging, high-sensitivity detection, and target-specific treatment. Recently, great efforts have been made in the developments of AuNCs as the fluorescent probes for various biomedical applications. In this review, we have collected fluorescent AuNCs prepared by different ligands, including small molecules, polymers, and biomacromolecules, and highlighted current achievements of AuNCs in biomedical applications for imaging, detection, and therapy. According to these advances, we further provided conclusions of present challenges and future perspectives of AuNCs for fundamental investigations and practical biomedical applications.

Recent advances in biomedical applications of fluorescent gold nanoclusters

Fluorescent gold nanoclusters (AuNCs) are emerging as novel fluorescent materials and have attracted more and more attention in the field of biolabeling, biosensing, bioimaging and targeted cancer treatment because of their unusual physicochemical properties, such as long fluorescence lifetime, ultrasmall size, large Stokes shift, strong photoluminescence, as well as excellent biocompatibility and photostability. Recently, significant efforts have been committed to the preparation, functionalization and biomedical application studies of fluorescent AuNCs. In this review, we have summarized the strategies for preparation and surface functionalization of fluorescent AuNCs in the past several years, and highlighted recent advances in the biomedical applications of the relevant fluorescent AuNCs. Based on these observations, we also give a discussion on the current problems and future developments of the fluorescent AuNCs for biomedical applications.

Fluorescent metal quantum clusters: an updated overview of the synthesis, properties, and biological applications

A brief history of metal quantum clusters, their synthesis methods, physical properties, and an updated overview of their applications is provided.

Polyethyleneimine-Coated Gold Nanoparticles: Straightforward Preparation of Efficient DNA Delivery Nanocarriers

A novel one-pot method for the synthesis of polyethyleneimine (PEI)-coated gold nanoparticles (AuPEI-NPs) that combines the reductant-stabilizer properties of PEI with microwave irradiation starting from hydrogen tetrachloroaurate acid (HAuCl₄ ) and branched PEI 25 kDa (b25kPEI) was explored. The method was straightforward, green, and low costing, for which the Au/PEI ratio (1:1 to 1:128 w/w) was a key parameter to modulate their capabilities as DNA delivery nanocarriers. Transfection assays in CHO-k1 cells demonstrated that AuPEI-NPs with 1:16 and 1:32 w/w ratios behaved as effective DNA gene vectors with improved transfection efficiencies (twofold) and significantly lower toxicity than unmodified b25kPEI and Lipofectamine 2000. The transfection mediated by these AuPEI-NP-DNA polyplexes preferentially used the caveolae-mediated route for intracellular internalization, as shown by studies performed by using specific internalization inhibitors as well as colocalization with markers of clathrin- and caveolae-dependent pathways. The AuPEI-NP polyplexes preferentially used the more efficient caveolae internalization pathway to promote transfection, a fact that supports their higher transfection efficiency relative to that of Lipofectamine 2000. In addition, intracellular trafficking of the AuPEI-NPs was studied by transmission electron microscopy.

Toward Chemical Perfection of Graphene-Based Gene Carrier via Ugi Multicomponent Assembly Process

The graphene-based materials with unique, versatile, and tunable properties have brought new opportunities for the leading edge of advanced nanobiotechnology. In this regard, the use of graphene in gene delivery applications is still at early stages. In this study, we successfully designed a new complex of carboxylated-graphene (G-COOH) with ethidium bromide (EtBr) and used it as a nanovector for efficient gene delivery into the AGS cells. G-COOH, with carboxyl functions on its surface, in the presence of EtBr, formaldehyde, and cyclohexylisocyanide were participated in Ugi four component reaction to fabricate a stable amphiphilic graphene-EtBr (AG-EtBr) composite. The coupling reaction was confirmed by further analyses with FT-IR, AFM, UV-vis, Raman, photoluminescence, EDS, and XPS. The AG-EtBr nanocomposite was able to interact with a plasmid DNA (pDNA). This nanocomposite has been applied for transfection of cultured mammalian cells successfully. Moreover, the AG-EtBr composites showed a remarkable decreased cytotoxicity in compared to EtBr. Interestingly, the advantages of AG-EtBr in cell transfection are more dramatic (3-fold higher) than Lipofectamine2000 as a commercial nonviral vector. To the best of our knowledge, this is the first report in which EtBr is used as an intercalating agent along with graphene to serve as a new vehicle for gene delivery application.

Metal nanoclusters: novel probes for diagnostic and therapeutic applications

Metal nanoclusters, composed of several to a few hundred metal atoms, have received worldwide attention due to their extraordinary physical and chemical characteristics. Recently, great efforts have been devoted to the exploration of the potential diagnostic and therapeutic applications of metal nanoclusters. Here we focus on the recent advances and new horizons in this area, and introduce the rising progress on the use of metal nanoclusters for biological analysis, biological imaging, therapeutic applications, DNA assembly and logic gate construction, enzyme mimic catalysis, as well as thermometers and pH meters. Furthermore, the future challenges in the construction of biofunctional metal nanoclusters for diagnostic and therapeutic applications are also discussed. We expect that the rapidly growing interest in metal nanocluster-based theranostic applications will certainly not only fuel the excitement and stimulate research in this highly active field, but also inspire broader concerns across various disciplines.

An overview of nanoparticles commonly used in fluorescent bioimaging

This article gives an overview of the various kinds of nanoparticles (NPs) that are widely used for purposes of fluorescent imaging, mainly of cells and tissues. Following an introduction and a discussion of merits of fluorescent NPs compared to molecular fluorophores, labels and probes, the article assesses the kinds and specific features of nanomaterials often used in bioimaging. These include fluorescently doped silicas and sol-gels, hydrophilic polymers (hydrogels), hydrophobic organic polymers, semiconducting polymer dots, quantum dots, carbon dots, other carbonaceous nanomaterials, upconversion NPs, noble metal NPs (mainly gold and silver), various other nanomaterials, and dendrimers. Another section covers coatings and methods for surface modification of NPs. Specific examples on the use of nanoparticles in (a) plain fluorescence imaging of cells, (b) targeted imaging, (c) imaging of chemical species, and (d) imaging of temperature are given next. A final section covers aspects of multimodal imaging (such as fluorescence/nmr), imaging combined with drug and gene delivery, or imaging combined with therapy or diagnosis. The electronic supplementary information (ESI) gives specific examples for materials and methods used in imaging, sensing, multimodal imaging and theranostics such as imaging combined with drug delivery or photodynamic therapy. The article contains 273 references in the main part, and 157 references in the ESI.

Interfacial synthesis of polyethyleneimine-protected copper nanoclusters: Size-dependent tunable photoluminescence, pH sensor and bioimaging

The copper nanoclusters (CuNCs) offer excellent potential as functional biological probes due to their unique photoluminescence (PL) properties. Herein, CuNCs capped with hyperbranched polyethylenimine (PEI) were prepared by the interfacial etching approach. The resultant PEI-CuNCs exhibited good dispersion and strong fluorescence with high quantum yields (QYs, up to 7.5%), which would be endowed for bioimaging system. By changing the reaction temperatures from 25 to 150 °C, the size of PEI-CuNCs changed from 1.8 to 3.5 nm, and thus tunable PL were achieved, which was confirmed by transmission electron microscopy (TEM) imagings and PL spectra. Besides, PEI-CuNCs had smart absorption characteristics that the color changes from colorless to blue with changing the pH value from 2.0 to 13.2, and thus they could be used as color indicator for pH detection. In addition, the PEI-CuNCs exhibited good biocompatibility and low cytotoxicity to 293T cells through MTT assay. Owing to the positively charged of PEI-CuNCs surface, they had the ability to capture DNA, and the PEI-CuNCs/DNA complexes could get access to cells for efficient gene expression. Armed with these attractive properties, the synthesized PEI-CuNCs are quite promising in biological applications.

Functionalization of metal nanoclusters for biomedical applications

Metal nanoclusters (NCs) are emerging as a new class of functional nanomaterials in the area of biological sensing, labelling, imaging and therapy due to their unique physical and chemical properties, such as ultrasmall size, HOMO–LUMO transition, strong luminescence together with good photostability and biocompatibility.

Influence of the size and charge of gold nanoclusters on complexation with siRNA: a molecular dynamics simulation study

The complexation of siRNA with positively charged gold nanoclusters has been studied using classical molecular dynamics simulations.

Diol glycidyl ether-bridged low molecular weight PEI as potential gene delivery vehicles

PEI 600-based polymers were synthesized via ring-opening polymerization and exhibited much better transfection efficiency and biocompatibility than PEI 25 kDa.

A fluorescent biosensor of lysozyme-stabilized copper nanoclusters for the selective detection of glucose

Fluorescent copper nanoclusters (Lys-CuNCs) were synthesized using lysozyme as a template, displaying smart response to glucose concentration with high sensitivity. The visualization variation of Lys-CuNCs may further enable the rapid and simple detection of blood glucose.

Efficient gene delivery and multimodal imaging by lanthanide-based upconversion nanoparticles

Nanoparticles have been explored as nonviral gene carriers for years because of the simplicity of surface modification and lack of immune response. Lanthanide-based upconversion nanoparticles (UCNPs) are becoming attractive candidates for biomedical applications in virtue of their unique optical properties and multimodality imaging ability. Here, we report a UCNPs-based structure with polyethylenimine coating for both efficient gene transfection and trimodality imaging. Cytotoxicity tests demonstrated that the nanoparticles exhibited significantly decreased cytotoxicity compared to polyethylenimine polymer. Further, in vitro studies revealed that the gene carriers are able to transfer the enhanced green fluorescence protein (EGFP) plasmid DNA into Hela cells in higher transfection efficiency than PEI. Gene silencing was also examined by delivering bcl-2 siRNA into Hela cells, resulting in significant downregulation of target bcl-2 mRNA. More importantly, we demonstrated the feasibility of upconversion gene carriers to serve as effective contrast agents for MRI/CT/UCL trimodality imaging both in vitro and in vivo. The facile fabrication process, great biocompatibility, enhanced gene transfection efficiency, and great bioimaging ability can make it promising for application in gene therapy.

Lipid nanocapsules functionalized with polyethyleneimine for plasmid DNA and drug co-delivery and cell imaging

The paper reports on the preparation of lipid nanocapsules (LNCs) functionalized with poly(ethyleneimine) (PEI) moieties and their successful use as drug and gene delivery systems. The cationic LNCs were produced by a phase inversion process with a nominal size of 25 nm and subsequently modified with PEI chains using a transacylation reaction. The functionalization process allowed good control over the nanoscale particle size (26.2 ± 3.9 nm) with monodisperse size characteristics (PI < 0.2) and positive surface charge up to +18.7 mV. The PEI-modified LNCs (LNC25-T) displayed good buffering capacity. Moreover, the cationic LNC25-T were able to condense DNA and form complexes via electrostatic interactions in a typical weight ratio-dependent relationship. It was found that the mean diameter of LNC25-T/pDNA complexes increased to ∼40-50 nm with the LNC25-T/pDNA ratio from 1 to 500. Gel electrophoresis and cell viability experiments showed that the LNC25-T/pDNA complexes had high stability with no cytotoxicity due to the anchored PEI polymers on the surface of LNCs. Finally, the transfection efficiency of the LNC25-T/pDNA complexes was studied and evaluated on HEK cell lines in comparison with free PEI/pDNA polyplexes. The combination of cationic LNCs with pDNA exhibited more than a 2.8-fold increase in transfection efficiency compared to the standard free PEI/pDNA polyplexes at the same PEI concentrations. Moreover, we have demonstrated that LNC25-T/pDNA loaded with a hydrophobic drug, paclitaxel, showed high drug efficacy. The high transfection efficiency combined with the potential of simultaneous co-delivery of hydrophobic drugs, relatively small size of LNC25-T/pDNA complexes, and fluorescence imaging can be crucial for gene therapy, as small particle sizes may be more favorable for in vivo studies.

Oligoamine-tethered low generation polyamidoamine dendrimers as potential nucleic acid carriers

Oligoamine-tethered low generation PAMAM dendrimers (mG2–mG4) have been synthesized, which showed significantly higher transfection efficiency with minimal cytotoxicity in vitro.

Simultaneous and multisite tumor rapid-target bioimaging through in vivo biosynthesis of fluorescent gold nanoclusters

In vivo simultaneous and multisite tumor rapid-targeting through specifically biosynthesized gold nanoclusters could be readily followed and monitored by real-time fluorescence imaging.