Construction of core-shell tecto dendrimers based on supramolecular host-guest assembly for enhanced gene delivery

Dendrimers as drug delivery systems for oncotherapy: Current status of promising applications

Cancer affects millions of people worldwide, causing death and serious health problems. Despite significant investment in the development of new anticancer compounds, there are still several limitations that can still be found. Many compounds exhibit high levels of toxicity and low bioavailability. Therefore, it is urgent to design safer, more effective, and particularly more selective compounds for oncological treatment. Dendrimers are polymeric structures that have been shown to be potential drug nanocarriers to overcome physicochemical, pharmacokinetic, and indirect pharmacodynamic issues. Due to their versatility, they can be used in the design of nanovaccines, lipophilic complexes, amphiphilic complexes, smart nanocomplexes, and others. This work targets the use of dendrimers in oncological treatment and their importance and effectiveness as drug delivery systems for the development of new therapies. For this review, only publications from the last two years are considered in this review.

Beyond Lipids: Exploring Advances in Polymeric Gene Delivery in the Lipid Nanoparticles Era

The recent success of gene therapy during the COVID-19 pandemic has underscored the importance of effective and safe delivery systems. Complementing lipid-based delivery systems, polymers present a promising alternative for gene delivery. Significant advances have been made in the recent past, with multiple clinical trials progressing beyond phase I and several companies actively working on polymeric delivery systems which provides assurance that polymeric carriers can soon achieve clinical translation. The massive advantage of structural tunability and vast chemical space of polymers is being actively leveraged to mitigate shortcomings of traditional polycationic polymers and improve the translatability of delivery systems. Tailored polymeric approaches for diverse nucleic acids and for specific subcellular targets are now being designed to improve therapeutic efficacy. This review describes the recent advances in polymer design for improved gene delivery by polyplexes and covalent polymer-nucleic acid conjugates. The review also offers a brief note on novel computational techniques for improved polymer design. The review concludes with an overview of the current state of polymeric gene therapies in the clinic as well as future directions on their translation to the clinic.

Structural and Property Characterizations of Dual-Responsive Core-Shell Tecto Dendrimers for Tumor Penetration and Gene Delivery Applications

Core-shell tecto dendrimers (CSTDs) with excellent physicochemical properties and good tumor penetration and gene transfection efficiency have been demonstrated to have the potential to replace high-generation dendrimers in biomedical applications. However, their characterization and related biological properties of CSTDs for enhanced tumor penetration and gene delivery still lack in-depth investigation. Herein, three types of dual-responsive CSTDs are designed for thorough physicochemical characterization and investigation of their tumor penetration and gene delivery efficiency. Three types of CSTDs are prepared through phenylborate ester bonds of phenylboronic acid (PBA)-decorated generation 5 (G5) poly(amidoamine) (PAMAM) dendrimers as cores and monose (galactose, glucose, or mannose)-conjugated G3 PAMAM dendrimers as shells and thoroughly characterized via NMR and other techniques. It is shown that the produced CSTDs display strong correlation signals between the PBA and monose protons, similar hydrodynamic diameters, and dual reactive oxygen species- and pH-responsivenesses. The dual-responsive CSTDs are proven to have structure-dependent tumor penetration property and gene delivery efficiency in terms of small interference RNA for gene silencing and plasmid DNA for gene editing, thus revealing a great potential for different biomedical applications.

Abelairas A, Criado A, Gómez IJ, Mosquera J. Dendrimers: Exploring Their Wide Structural Variety and Applications

Dendrimers constitute a distinctive category of synthetic materials that bear resemblance to proteins in various aspects, such as discrete structural organization, globular morphology, and nanoscale dimensions. Remarkably, these attributes coexist with the capacity for facile large-scale production. Due to these advantages, the realm of dendrimers has undergone substantial advancement since their inception in the 1980s. Numerous reviews have been dedicated to elucidating this subject comprehensively, delving into the properties and applications of quintessential dendrimer varieties like PAMAM, PPI, and others. Nevertheless, the contemporary landscape of dendrimers transcends these early paradigms, witnessing the emergence of a diverse array of novel dendritic architectures in recent years. In this review, we aim to present a comprehensive panorama of the expansive domain of dendrimers. As such, our focus lies in discussing the key attributes and applications of the predominant types of dendrimers existing today. We will commence with the conventional variants and progressively delve into the more pioneering ones, including Janus, supramolecular, shape-persistent, and rotaxane dendrimers.

A tumor microenvironment-responsive core-shell tecto dendrimer nanoplatform for magnetic resonance imaging-guided and cuproptosis-promoted chemo-chemodynamic therapy

Theranostic nanoplatforms for combination tumor therapy have gained lots of attention recently due to the optimized therapeutic efficiency and simultaneous diagnosis performance. Herein, a novel tumor microenvironment (TME)-responsive core-shell tecto dendrimer (CSTD) was assembled by phenylboronic acid- and mannose-modified poly(amidoamine) dendrimers via the phenylboronic ester bonds that are responsive to low pH and reactive oxygen species (ROS), and efficiently loaded with copper ions and chemotherapeutic drug disulfiram (DSF) for tumor-targeted magnetic resonance (MR) imaging and cuproptosis-promoted chemo-chemodynamic therapy. The formed CSTD-Cu(II)@DSF could be specifically taken up by MCF-7 breast cancer cells, accumulated to the tumor model after circulation, and released drugs in response to the weakly acidic TME with overexpressed ROS. The enriched intracellular Cu(II) ions could induce the oligomerization of lipoylated proteins and proteotoxic stress for cuproptosis, and lipid peroxidation for chemodynamic therapy as well. Moreover, the CSTD-Cu(II)@DSF could cause the dysfunction of mitochondria and arrest the cell cycle at the G2/M phase, leading to enhanced DSF-mediated cell apoptosis. As a result, CSTD-Cu(II)@DSF could effectively inhibit the growth of MCF-7 tumors by a combination therapy strategy integrating chemotherapy with cuproptosis and chemodynamic therapy. Lastly, the CSTD-Cu(II)@DSF also displays Cu(II)-associated r1 relaxivity, allowing for T1-weighted real-time MR imaging of tumors in vivo. The developed tumor-targeted and TME-responsive CSTD-based nanomedicine formulation may be developed for accurate diagnosis and synergistic treatment of other cancer types. STATEMENT OF SIGNIFICANCE: Constructing an effective nanoplatform for the combination of therapeutic effects and real-time tumor imaging remains a challenge. In this study, we reported for the first time an all-in-one tumor-targeted and tumor microenvironment (TME) responsive nanoplatform based on core-shell tecto dendrimer (CSTD) for the cuproptosis-promoted chemo-chemodynamic therapy and enhanced MR imaging. The efficient loading, selective tumor-targeting, and TME-responsive release of Cu(II) and disulfiram could enhance the intracellular accumulation of drugs, induce cuproptosis of cancer cells, and amplify the synergistic chemo-chemodynamic therapeutic effect, resulting in enhanced MR imaging and accelerated tumor eradication. This study sheds new light on the development of theranostic nanoplatforms for early accurate diagnosis and effective treatment of cancers.

Non-Viral Carriers for Nucleic Acids Delivery: Fundamentals and Current Applications

Over the past decades, non-viral DNA and RNA delivery systems have been intensively studied as an alternative to viral vectors. Despite the most significant advantage over viruses, such as the lack of immunogenicity and cytotoxicity, the widespread use of non-viral carriers in clinical practice is still limited due to the insufficient efficacy associated with the difficulties of overcoming extracellular and intracellular barriers. Overcoming barriers by non-viral carriers is facilitated by their chemical structure, surface charge, as well as developed modifications. Currently, there are many different forms of non-viral carriers for various applications. This review aimed to summarize recent developments based on the essential requirements for non-viral carriers for gene therapy.

Dual-Responsive Core-Shell Tecto Dendrimers Enable Efficient Gene Editing of Cancer Cells to Boost Immune Checkpoint Blockade Therapy

Immune checkpoint blockade (ICB) therapy has become a promising strategy in treating multiple tumor types, but the therapeutic efficacy is still unsatisfactory due to the temporary and inefficient blocking and the poor immune responsiveness. Herein, we report the development of dual reactive oxygen species (ROS)- and pH-responsive core-shell tecto dendrimers loaded with gold nanoparticles (for short, Au CSTDs) to deliver a plasmid-clustered regularly interspersed short palindromic repeats (CRISPR)/Cas9 system for the permanent disruption of the programmed death ligand 1 (PD-L1) gene in cancer cells to boost cancer immunotherapy. In our work, Au CSTDs were constructed using lactobionic acid (LA)-modified generation 5 poly(amidoamine) dendrimers entrapped with gold nanoparticles as cores and phenylboronic acid (PBA)-conjugated generation 3 dendrimers as shells via the formation of responsive phenylborate ester bonds between PBA and LA. The plasmid-CRISPR/Cas9 system can be efficiently compacted and specifically taken up by cancer cells overexpressing sialic acids due to the PBA-mediated targeting and be responsively released in cancer cells by the responsive dissociation of the Au CSTDs, leading to the successful endosomal escape and the efficient knockout of the PD-L1 gene. Further in vivo delivery in a mouse melanoma model reveals that the developed Au CSTDs/plasmid-CRISPR/Cas9 complexes can be specifically accumulated at the tumor site for enhanced computed tomography (CT) imaging of tumors, owing to the X-ray attenuation effect of Au, and disrupt the PD-L1 expression in tumor cells, thus promoting the ICB-based antitumor immunity. The designed dual-responsive Au CSTDs may be developed as a versatile tool for genetic engineering of other cell types to achieve different therapeutic effects for expanded space of biomedical applications.

Cyclodextrin regulated natural polysaccharide hydrogels for biomedical applications-a review

Cyclodextrin and its derivative (CDs) are natural building blocks for linking with other components to afford functional biomaterials. Hydrogels are polymer network systems that can form hydrophilic three-dimensional network structures through different cross-linking methods and are developing as potential materials in biomedical applications. Natural polysaccharide hydrogels (NPHs) are widely adopted in biomedical field with good biocompatibility, biodegradability, low cytotoxicity, and versatility in emulating natural tissue properties. Compared with conventional NPHs, CD regulated natural polysaccharide hydrogels (CD-NPHs) maintain good biocompatibility, while improving poor mechanical qualities and unpredictable gelation times. Recently, there has been increasing and considerable usage of CD-NPHs while there is still no review comprehensively introducing their construction, classification, and application of these hydrogels from the material point of view regarding biomedical fields. To draw a complete picture of the current and future development of CD-NPHs, we systematically overview the classification of CD-NPHs, and provide a holistic view on the role of CD-NPHs in different biomedical fields, especially in drug delivery, wound dressing, cell encapsulation, and tissue engineering. Moreover, the current challenges and prospects of CD-NPHs are discussed rationally, providing an insight into developing vibrant fields of CD-NPHs-based biomedicine, and facilitating their translation from bench to clinical medicine.

Co-delivery of Dexamethasone and a MicroRNA-155 Inhibitor Using Dendrimer-Entrapped Gold Nanoparticles for Acute Lung Injury Therapy

Development of nanomedicines for effective therapy of acute lung injury (ALI), a common critical respiratory failure syndrome, remains to be challenging. We report here a unique design of a functional nanoplatform based on generation 5 (G5) poly(amidoamine) dendrimer-entrapped gold nanoparticles (Au DENPs) to co-deliver dexamethasone (Dex) and a microRNA-155 inhibitor (miR-155i) for combination chemotherapy and gene therapy of ALI. In this study, we synthesized Au DENPs with 10 Dex moieties attached per G5 dendrimer and an Au core diameter of 2.1 nm and used them to compress miR-155i. The generated polyplexes own a positive zeta potential (16-26 mV) and a small hydrodynamic diameter (175-230 nm) and display desired cytocompatibility and efficient miR-155i delivery to lipopolysaccharide (LPS)-activated alveolar macrophages, thus upregulating the suppressor of cytokine signaling 1 and IL-10 expression and downregulating the pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6). Likewise, as a synthetic glucocorticoid with a potent anti-inflammatory property, the attached Dex on the surface of Au DENPs could inhibit pro-inflammatory cytokine secretion by down-regulating cyclooxygenase-2 expression in the LPS-activated alveolar macrophages. The integration of Dex and miR-155i within one nanoformulation enables superior downregulation of pro-inflammatory cytokines for successful repair of damaged lung tissues in an ALI model, as demonstrated by histological examinations and pro-inflammatory cytokine downregulation in ALI lesion at the gene and protein levels. Such a combined chemotherapy and gene therapy strategy enabled by dendrimer nanotechnology may hold great promise to treat other types of inflammatory diseases.

Facile Formation of PAMAM Dendrimer Nanoclusters for Enhanced Gene Delivery and Cancer Gene Therapy

Preparation of versatile and safe nanovectors for efficient cancer gene therapy remains to be challenging in the current nanomedicine. Herein, we report the formation of dendrimer nanoclusters for enhanced gene delivery toward gene therapy of cancer. Here, poly(amidoamine) (PAMAM) dendrimers of generation 3 (G3) were cross-linked with 4,4'-dithiodibutryic acid (DA) to form nanoclusters (NCs) through 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride-induced covalent bonding. The synthesized G3-DA NCs having a hydrodynamic size of 219.3 nm possess good colloidal stability and can condense pDNA, encoding both enhanced green fluorescent protein and tumor suppressor p53 gene to form polyplexes with good cytocompatibility. Strikingly, the created NCs/pDNA polyplexes enable 2.3 and 2.1 times higher gene transfection to cancer cells than the counterpart materials of single G3 and G5 PAMAM dendrimers, respectively, under the same conditions. Furthermore, polyplex-treated cancer cells have upregulated p53 and p21 protein and mRNA expression levels and downregulated Cyclin-D1 and CDK-4 protein and mRNA expressions, thus arresting the cell cycle to the G1 phase in vitro to achieve cancer cell gene therapy. The gene delivery efficiency of the polyplexes was further validated through the in vivo tumor therapy without systemic toxicity. The synthesized highly efficient dendrimer NC-based vector system with low cytotoxicity may be extended to tackle various types of diseases related to genetic disorders.

Impact of molecular rigidity on the gene delivery efficiency of core-shell tecto dendrimers

We report the construction of two types of core-shell tecto dendrimers (CSTDs) with different core rigidities to illustrate the impact of molecular rigidity on their gene delivery efficiency. Our study reveals that CSTDs designed with rigid cores enable promoted gene delivery, providing many possibilities for a wide range of gene delivery-associated biomedical applications.

Cyclodextrins in drug delivery: applications in gene and combination therapy

Gene therapy is a powerful tool against genetic disorders and cancer, targeting the source of the disease rather than just treating the symptoms. While much of the initial success of gene delivery relied on viral vectors, non-viral vectors are emerging as promising gene delivery systems for efficacious treatment with decreased toxicity concerns. However, the delivery of genetic material is still challenging, and there is a need for vectors with enhanced targeting, reduced toxicity, and controlled release. In this article, we highlight current work in gene therapy which utilizes the cyclic oligosaccharide molecule cyclodextrin (CD). With a number of unique abilities, such as hosting small molecule drugs, acting as a linker or modular component, reducing immunogenicity, and disrupting membranes, CD is a valuable constituent in many delivery systems. These carriers also demonstrate great promise in combination therapies, due to the ease of assembling macromolecular structures and wide variety of chemical derivatives, which allow for customizable delivery systems and co-delivery of therapeutics. The use of combination and personalized therapies can result in improved patient health-modular systems, such as those which incorporate CD, are more conducive to these therapy types. Graphical abstract.

Innovations in Biomaterial Design toward Successful RNA Interference Therapy for Cancer Treatment

Gene regulation using RNA interference (RNAi) therapy has been developed as one of the frontiers in cancer treatment. The ability to tailor the expression of genes by delivering synthetic oligonucleotides to tumor cells has transformed the way scientists think about treating cancer. However, its clinical application has been limited due to the need to deliver synthetic RNAi oligonucleotides efficiently and effectively to target cells. Advances in nanotechnology and biomaterials have begun to address the limitations to RNAi therapeutic delivery, increasing the likelihood of RNAi therapeutics for cancer treatment in clinical settings. Herein, innovations in the design of nanocarriers for the delivery of oligonucleotides for successful RNAi therapy are discussed.

Developments in Treatment Methodologies Using Dendrimers for Infectious Diseases

Dendrimers comprise a specific group of macromolecules, which combine structural properties of both single molecules and long expanded polymers. The three-dimensional form of dendrimers and the extensive possibilities for use of additional substrates for their construction creates a multivalent potential and a wide possibility for medical, diagnostic and environmental purposes. Depending on their composition and structure, dendrimers have been of interest in many fields of science, ranging from chemistry, biotechnology to biochemical applications. These compounds have found wide application from the production of catalysts for their use as antibacterial, antifungal and antiviral agents. Of particular interest are peptide dendrimers as a medium for transport of therapeutic substances: synthetic vaccines against parasites, bacteria and viruses, contrast agents used in MRI, antibodies and genetic material. This review focuses on the description of the current classes of dendrimers, the methodology for their synthesis and briefly drawbacks of their properties and their use as potential therapies against infectious diseases.

Core-Shell Tecto Dendrimers Enable Enhanced Tumor MR Imaging through an Amplified EPR Effect

Development of nanoplatforms that can amplify the passive tumor targeting effect based on enhanced permeability and retention (EPR) effect is crucial for precision cancer nanomedicine applications. Herein, we present the development of core-shell tecto dendrimers (CSTDs) as a platform for enhanced tumor magnetic resonance (MR) imaging through an amplified EPR effect. In this work, poly(amidoamine) (PAMAM) dendrimers of generation 5 (G5) were decorated with β-cyclodextrin (CD) and then assembled with G3 PAMAM dendrimers premodified with adamantane (Ad) via supramolecular recognition of CD and Ad. The formed G5-CD/Ad-G3 CSTDs were conjugated with tetraazacyclododecane tetraacetic acid (DOTA)-Gd(III) chelators and further acetylated to neutralize the remaining CSTD periphery amines. We reveal that the formed CSTD.NHAc-DOTA(Gd) (CSTD-D-Gd) complexes have a narrow size distribution and satisfactory colloidal stability, and are cytocompatible within the concentration range studied. Compared to the single dendrimer counterpart of G5.NHAc-DOTA(Gd) (G5-D-Gd) complexes, the CSTD-D-Gd complexes with a higher molecular weight and volume possess a longer rotation correlation time, hence having a longitudinal relaxivity (r₁) of 7.34 mM^-1 s^-1, which is 1.5 times larger than that of G5-D-Gd complexes (4.92 mM^-1 s^-1). More importantly, the CSTD-D-Gd complexes display better permeability in the three-dimensional (3D) cell spheroids in vitro through fluorescence imaging and a more significant EPR effect for improved tumor MR imaging in vivo than the G5-DOTA-Gd complexes. The generated CSTD-D-Gd complexes may be adopted for enhanced tumor MR imaging through an amplified passive EPR effect and also be further extended for different cancer theranostic applications.

Efficient co-delivery of microRNA 21 inhibitor and doxorubicin to cancer cells using core-shell tecto dendrimers formed via supramolecular host-guest assembly

Development of versatile and powerful nanoplatforms for efficient therapeutic delivery represents a major topic for current nanomedicine. Herein, we present the development of core-shell tecto dendrimers (CSTDs) for co-delivery of a therapeutic gene and drug for enhanced anticancer therapy applications. In this work, CSTDs were first prepared via supramolecular recognition of β-cyclodextrin (CD)-decorated generation 5 (G5) poly(amidoamine) (PAMAM) dendrimers as cores and adamantane (Ad)-functionalized G3 PAMAM dendrimers as shell components. The formed CSTDs with each G5 dendrimer surrounded with 4.2 G3 dendrimers were evaluated as a gene vector for delivery of plasmid DNA encoding enhanced green fluorescent protein as well as microRNA 21 inhibitor (miR 21i). We show that under an appropriate N/P ratio, the CSTDs enable effective transfection of both genetic materials to cancer cells. In particular, the transfection of miR 21i led to the inhibition of cancer cell migration, decreased miR 21 gene expression, and the effective regulation of the target genes and proteins (e.g., PTEN, PDCD4, p53, and Caspase-3). Furthermore, we revealed that the CSTDs were able to co-deliver miR 21i and an anticancer drug doxorubicin, leading to enhanced therapeutic efficacy to cancer cells in vitro. Our findings imply that the developed CSTDs could be adopted as a versatile platform for effective co-delivery of different therapeutic components for enhanced anticancer therapy applications.

Dendrimer-based nanohybrids in cancer photomedicine

Cancer phototherapy with non-invasiveness and high therapeutical efficiency has emerged as a hot spot research in cancer management. Various nanomaterials have been involved in the development of novel photoactive agents to overcome the current limitations in cancer phototherapy. Dendrimers, as an excellent nanocarrier with unique physicochemical properties, have received extensive attention and much effort has been made in the development of dendrimer-based hybrid platforms for photomedicine applications. Dendrimers can be entrapped with photosensitive agents within their internal cavities and be surface modified with reactive molecules, constructing multifunctional nanoplatforms for cancer treatment. In this review, we concisely survey the design of several different kinds of dendrimer-based nanohybrids for cancer photomedicine applications, and provide an overview of their recent applications in molecular imaging, single-modality photothermal therapy or photodynamic therapy, combination therapy, and theranostics of cancer. In addition, we also briefly discuss the future perspectives in the area of dendrimer-based nanohybrids for cancer photomedicine.

Construction of Poly(amidoamine) Dendrimer/Carbon Dot Nanohybrids for Biomedical Applications

Design of intelligent hybrid nanoparticles that can integrate diagnosis and therapy components plays an important role in the field of nanomedicine. Poly(amidoamine) (PAMAM) dendrimers possessing a unique architecture and tunable functional groups have been widely developed for various biomedical applications. Carbon dots (CDs) are considered as a promising fluorescence probe or drug delivery system due to their stable fluorescence property and excellent biocompatibility. The distinctive merits of PAMAM dendrimers and CDs are amenable for them to be constructed as perfect nanohybrids for different biomedical applications, in particular for cancer nanomedicine. Here, the recent advances in the construction of PAMAM dendrimer/CD nanohybrids for diverse biomedical applications, in particular for sensing and cancer theranostics are summarized. Finally, the future perspectives of the PAMAM dendrimer/CD nanohybrids are also briefly discussed.

Synthesis and Shaping of Core-Shell Tecto Dendrimers for Biomedical Applications

In recent years, the use of poly(amidoamine) (PAMAM) dendrimers of different generations as building blocks or reactive modules to construct core-shell tecto dendrimers (CSTDs) that are superior to the performance of single-generation dendrimers has received great attention in the field of biomedical applications. The CSTDs are always based on high-generation dendrimers as the core and low-generation dendrimers as the shell; not only do they have excellent properties similar to single high-generation dendrimers, but they also have overcome some of the shortcomings (e.g., limited drug loading capacity or enhanced permeability and retention effect due to small size) of single-generation dendrimers in biomedical applications. Herein, the recent advances of CSTDs synthesized by different approaches as nanoplatforms for different biomedical applications, particularly for chemotherapy, gene delivery, and combination therapy, as well as biological imaging, are summarized. In addition, the current challenges and future perspectives of CSTDs are also discussed.

Sulfonimide-Based Dendrimers: Progress in Synthesis, Characterization, and Potential Applications

There are more than 50 families of dendrimers, and some of which, such as polyamidoamine PAMAM, are well studied, and some are just starting to attract the attention of researchers. One promising type of dendrimers is sulfonimide-based dendrimers (SBDs). To date, SBDs are used in organic synthesis as starting reagents for the convergent synthesis of higher generations dendrimers, in materials science as alternative electrolyte solutions for fuel cells, and in medicinal chemistry as potential substances for drug transfer procedures. Despite the fact that most dendrimers are amorphous substances among the SBDs, several structures are distinguished that are prone to the formation of crystalline solids with melting points in the range of 120-250 °C. Similar to those of other dendrimers, the chemical and physical properties of SBDs depend on their outer shell, which is formed by functional groups. To date, SBDs decorated with end groups such as naphthyl, nitro, methyl, and methoxy have been successfully synthesized, and each of these groups gives the dendrimers specific properties. Analysis of the structure of SBD, their synthesis methods, and applications currently available in the literature reveals that these dendrimers have not yet been fully explored.

Recent advances in development of dendritic polymer-based nanomedicines for cancer diagnosis

Dendritic polymers have highly branched three-dimensional architectures, the fourth type apart from linear, cross-linked, and branched one. They possess not only a large number of terminal functional units and interior cavities, but also a low viscosity with weak or no entanglement. These features endow them with great potential in various biomedicine applications, including drug delivery, gene therapy, tissue engineering, immunoassay and bioimaging. Most review articles related to bio-related applications of dendritic polymers focus on their drug or gene delivery, while very few of them are devoted to their function as cancer diagnosis agents, which are essential for cancer treatment. In this review, we will provide comprehensive insights into various dendritic polymer-based cancer diagnosis agents. Their classification and preparation are presented for readers to have a precise understanding of dendritic polymers. On account of physical/chemical properties of dendritic polymers and biological properties of cancer, we will suggest a few design strategies for constructing dendritic polymer-based diagnosis agents, such as active or passive targeting strategies, imaging reporters-incorporating strategies, and/or internal stimuli-responsive degradable/enhanced imaging strategies. Their recent applications in in vitro diagnosis of cancer cells or exosomes and in vivo diagnosis of primary and metastasis tumor sites with the aid of single/multiple imaging modalities will be discussed in great detail. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > in vivo Nanodiagnostics and Imaging Diagnostic Tools > in vitro Nanoparticle-Based Sensing.

Speedy one-pot electrochemical synthesis of giant octahedrons from in situ generated pyrrolidinyl PAMAM dendrimer

A novel electrochemical synthesis via a radical generation pathway is described here for the generation of a quaternary megamer structure from secondary dendrimers. The reaction is rapid and completes in <5 min. We have used lower/higher generation poly(amido)amine (PAMAM) dendrimers with carboxylic acid groups at the terminals. A precise electrocatalytic reaction at >3.5 V activates the carboxylic groups to undergo anodic oxidation (-e-) and produce radical carboxylate anions on the dendrimer surface. The reaction further goes through a decarboxylative elimination. Successive self-assembly creates billions of polydispersed and extremely stable ∼500 nm octahedron nanostructures, which we failed to destroy even by using a 20 kV electron beam. This is a new route for the speedy synthesis of important futuristic materials of well-defined shape. It has applications in building designer organic crystals for solar cells, organic electronics, rapid protein gelation, rapid protein crystallization, etc.

Core-shell tecto dendrimers formed via host-guest supramolecular assembly as pH-responsive intelligent carriers for enhanced anticancer drug delivery

The design of pH-sensitive supramolecular drug delivery systems for efficient antineoplastic drug delivery remains a huge challenge. Herein, we describe the development of pH-responsive core-shell tecto dendrimers (CSTDs) formed using benzimidazole (BM)-modified generation 3 (G3) poly(amidoamine) (PAMAM) dendrimers (G3.NHAc-BM) as a shell and β-cyclodextrin (CD)-modified G5 PAMAM dendrimers (G5.NHAc-CD) as a core. By virtue of the host-guest recognition and pH-responsiveness of BM/β-CD assembly, the pH-sensitive supramolecular CSTDs of G5.NHAc-CD/BM-G3.NHAc were formed and adopted to encapsulate the anticancer drug doxorubicin (DOX) via hydrophobic interactions for pH-responsive drug delivery applications. The synthesis of dendrimer derivatives and the loading of the DOX were well characterized via different methods. We show that the encapsulated DOX can be released in a sustained manner with a rapid release speed under a slightly acidic pH condition (pH < 6), which is similar to acidic tumor microenvironment. The enhanced intracellular release of DOX and improved anticancer activity of the drug-loaded pH-responsive CSTDs were demonstrated and compared with the control CSTDs formed without pH-responsiveness through flow cytometry and viability assays of cancer cells. Furthermore, the pH-sensitive CSTDs also showed efficient drug penetration and growth inhibition of three-dimensional tumor spheroids owing to the faster DOX release in an acidic pH environment. The pH-sensitive G5.NHAc-CD/BM-G3.NHAc CSTDs may be employed as a valuable intelligent delivery system for various anticancer drugs.

Zwitterion-functionalized dendrimer-entrapped gold nanoparticles for serum-enhanced gene delivery to inhibit cancer cell metastasis

We demonstrate a novel serum-enhanced gene delivery approach using zwitterion-functionalized dendrimer-entrapped gold nanoparticles (Au DENPs) as a non-viral vector for inhibition of cancer cell metastasis in vitro. Poly(amidoamine) dendrimers of generation 5 decorated with zwitterion carboxybetaine acrylamide (CBAA) and lysosome-targeting agent morpholine (Mor) were utilized to entrap gold NPs. We show that both Mor-modified and Mor-free Au DENPs are cytocompatible and can effectively deliver plasmid DNA encoding different reporter genes to cancer cells in medium with or without serum. Strikingly, due to the antifouling property exerted by the attached zwitterion CBAA, the gene delivery efficiency of Mor-modified Au DENPs and the Mor-free Au DENPs in the serum-containing medium are 1.4 and 1.7 times higher than the corresponding vector in serum-free medium, respectively. In addition, the Mor-free vector has a better gene expression efficiency than the Mor-modified one although the Mor modification enables the polyplexes to have enhanced cancer cell uptake. Wound healing and hypermethylated in cancer 1 (HIC1) protein expression assay data reveal that the expression of HIC1 gene in cancer cells enables effective inhibition of cell migration. Our findings suggest that the created zwitterion-functionalized Au DENPs may be employed as a powerful vector for serum-enhanced gene therapy of different diseases. STATEMENT OF SIGNIFICANCE: One major challenge in the non-viral gene delivery system is that the strong interaction between serum protein and the positively charged vector/gene polyplexes neutralize the positive charge of the polyplexes and form possible protein corona, thereby significantly reducing their cellular uptake efficiency and subsequent gene transfection outcome. Here we demonstrate the conceptual advances in the serum-enhanced gene delivery using zwitterionic modification of polycationic poly(amidoamine) (PAMAM) dendrimer-entrapped gold nanoparticles (Au DENPs). We demonstrate that partial zwitterionic modification of Au DENPs is able to confer them with antifouling property to resist serum protein adsorption. Hence the vector/DNA polyplexes are able to maintain their positive potentials and small hydrodynamic size in the serum environment, where serum solely play the role as a nutrition factor for enhanced gene delivery. We demonstrate that partial modification of zwitterion carboxybetaine acrylamide (CBAA) and morpholine (Mor) onto the surface Au DENPs renders the vector with both antifouling property and lysosome targeting ability, respectively. The generated functional Au DENPs can compact pDNA to form polyplexes that enable serum-enhanced gene expression. In particular, once complexed with hypermethylated in cancer 1 (HIC1) gene, the polyplexes can significantly inhibit cancer cell migration and metastasis.

Plasmid-Templated Control of DNA-Cyclodextrin Nanoparticle Morphology through Molecular Vector Design for Effective Gene Delivery

Engineering self-assembled superstructures through complexation of plasmid DNA (pDNA) and single-isomer nanometric size macromolecules (molecular nanoparticles) is a promising strategy for gene delivery. Notably, the functionality and overall architecture of the vector can be precisely molded at the atomic level by chemical tailoring, thereby enabling unprecedented opportunities for structure/self-assembling/pDNA delivery relationship studies. Beyond this notion, by judiciously preorganizing the functional elements in cyclodextrin (CD)-based molecular nanoparticles through covalent dimerization, here we demonstrate that the morphology of the resulting nanocomplexes (CDplexes) can be tuned, from spherical to ellipsoidal, rod-type, or worm-like nanoparticles, which makes it possible to gain understanding of their shape-dependent transfection properties. The experimental findings are in agreement with a shift from chelate to cross-linking interactions on going from primary-face- to secondary-face-linked CD dimers, the pDNA partner acting as an active payload and as a template. Most interestingly, the transfection efficiency in different cells was shown to be differently impacted by modifications of the CDplex morphology, which has led to the identification of an optimal prototype for tissue-selective DNA delivery to the spleen in vivo.