Near-Infrared Fluorescent Micelles from Poly(norbornene) Brush Triblock Copolymers for Nanotheranostics

Photothermal Particle-Loaded Panax Notoginseng Polysaccharide Cryogels As Personalized Tumor Vaccines

Combination immunotherapy is being increasingly explored for cancer treatment, leading to various vector materials for the codelivery of immune agents and drugs. However, current tumor vaccines exhibit poor immunogenicity, severely compromising their therapeutic efficacy. Herein, an injectable hydrogel was developed based on dopamine (DA) and Panax notoginseng polysaccharide (PNPS) loaded with hair microparticles (HMPs) to enhance the immunogenicity of tumor vaccines. Photothermal effects of incorporated HMPs can trigger immunogenic cancer cell death and the release of abundant autologous tumor antigens, which are captured by catechol groups. Concomitant breakdown of PNPS recruits and activates dendritic cells (DCs). The macroporous structure of cryogels allows immune cell infiltration and interaction with antigens adsorbed on PNPS and DA cryogels (PD cryogels), thereby provoking potent cytotoxic T-cell responses. Hence, PD cryogels enabling cell infiltration and accelerated DC maturation may serve as a therapeutic vaccination platform against cancer.

Size- and Shape-controlled Biodegradable Polymer Brushes Based on l-Amino Acid for Intracellular Drug Delivery and Deep-Tissue Penetration

We report size- and shape-controlled polymer brushes based on l-amino acid bioresource and study the role of polymer topology on the enzymatic biodegradation and deep-tissue penetration under in vitro and in vivo. For this purpose, l-tyrosine-based propargyl-functionalized monomer is tailor-made and polymerized via solvent-free melt polycondensation strategy to yield hydrophobic and clickable biodegradable poly(ester-urethane)s. Postpolymerization click chemistry strategy is applied to make well-defined amphiphilic one-dimensional rodlike and three-dimensional spherical polymer brushes by merely varying the lengths of PEG-azides in the reaction. These core-shell polymer brushes are found to be nontoxic and nonhemolytic and capable of loading clinical anticancer drug doxorubicin and deep-tissue penetrable near-infrared biomarker IR-780. In vitro enzymatic drug-release kinetics and lysotracker-assisted real-time live-cell confocal bioimaging revealed that the rodlike polymer brush is superior than its spherical counterparts for faster cellular uptake and enzymatic biodegradation at the endolysosomal compartments to release DOX at the nucleus. Further, in vivo live-animal bioimaging by IVIS technique established that the IR-780-loaded rodlike polymer brush exhibited efficient deep-tissue penetration ability and emphasized the importance of polymer brush topology control for biological activity. Polymer brushes exhibit good stability in the blood plasma for more than 72 h, they predominately accumulate in the digestive organs like liver and kidney, and they are less toxic to heart and brain tissues. IVIS imaging of cryotome tissue slices of organs confirmed the deep-penetrating ability of the polymer brushes. The present investigation opens opportunity for bioderived and biodegradable polymer brushes as next-generation smart drug-delivery scaffolds.

Ephedra intermedia Schrenk & C. A. Mey Methanol Extract: Nanoencapsulation by Mini-Emulsion Polymerization and its Release Trend under Simulated Conditions of the Human Body

In this research, the extract of Ephedra intermedia Schrenk & C.A.Mey. was encapsulated using the mini-emulsion polymerization method based on methyl methacrylate polymers with a nanometer size. The encapsulated extract was characterized using different analytical techniques. Furthermore, the loading efficiency and release of the plant extract were examined. FT-IR spectroscopy confirmed the formation of an expectational product. The TEM and SEM imaging showed a spherical morphology for the prepared encapsulated extract. The average size of poly-methyl-methacrylate nanoparticles containing Ephedra extract was found to be approximately 47 nm. The extract loading efficiency and encapsulation efficiency test demonstrated a dose-depending behavior on E. intermedia extract for both analyses, which is highly advantageous for traversing biological barriers. The release assay shows a controlled release for the extract at phosphate buffer solution (PBS). A 38 % release was calculated after 36 hours. The results obtained from the present study reveal that encapsulating the plant extract is a suitable alternative to control and increase their medicinal properties.

Self-Report Amphiphilic Polymer-Based Drug Delivery System with ROS-Triggered Drug Release for Osteoarthritis Therapy

The development of drug delivery systems with real-time cargo release monitoring capabilities is imperative for optimizing nanomedicine performance. Herein, we report an innovative self-reporting drug delivery platform based on a ROS-responsive random copolymer (P1) capable of visualizing cargo release kinetics via the activation of an integrated fluorophore. P1 was synthesized by copolymerization of pinacol boronate, PEG, and naphthalimide monomers to impart ROS-sensitivity, hydrophilicity, and fluorescence signaling, respectively. Detailed characterization verified that P1 self-assembles into 11 nm micelles with 10 μg mL-1 CMC and can encapsulate hydrophobic curcumin with 79% efficiency. Fluorescence assays demonstrated H2O2-triggered disassembly and curcumin release with concurrent polymer fluorescence turn-on. Both in vitro and in vivo studies validated the real-time visualization of drug release and ROS scavenging, as well as the therapeutic effect on osteoarthritis (OA). Overall, this nanotheranostic polymeric micelle system enables quantitative monitoring of drug release kinetics for enhanced treatment optimization across oxidative stress-related diseases.

Unsynchronous conformational transitions induced by the asymmetric adsorption-response of an active diblock copolymer in an inert brush

To exploit the chemical asymmetry of diblock copolymer chains on the design of high-performance switch sensors, we propose an analytically tractable model system which contains an adsorption-responsive diblock copolymer in an otherwise inert brush, and study its phase transitions by using both analytical theory and self-consistent field calculations. The copolymer chain is chemically asymmetric in the sense that the two blocks assume different adsorption strengths, which is characterized by the defined adsorption ratio. We found that the conformation states, the number of stable phases, and transition types are mainly controlled by the length of each block and the adsorption ratio. In particular, when the length of the ungrafted block is longer than the brush chains, and the adsorption ratio is smaller than a critical value, the copolymer chain shows three thermodynamically stable states, and undergoes two unsynchronous transitions, where the two blocks respond to the adsorption in a different manner, when the adsorption changes from weak to sufficiently strong. For this kind of three-state transition, the transition point, transition barrier, and transition width are evaluated by using the self-consistent field method, and their scaling relationship with respect to the system parameters is extracted, which matches reasonably well with the predictions from the analytical theory. The self-consistent field calculations also indicate that the conformational transitions involved in the three-state transition process are sharp with a low energy barrier, and interestingly, barrier-free transitions are observed. Our finding shows that the three-state transitions not only specify a region where high performance unsynchronous switch sensors can be exploited, but may also provide a useful model understanding the unsynchronous biological processes.

Well-Defined Bifunctional Dendrimer Bearing 54 Nitric Oxide-Releasing Moieties and 54 Ursodeoxycholic Acid Groups Presenting High Anti-Inflammatory Activity

Nitric oxide (NO) and ursodeoxycholic acid (UDCA) are endogenous molecules involved in physiological processes associated with inflammation. Since inflammatory processes are present in the mechanisms of many diseases, these molecules are important for the development of new drugs. Herein, we describe the synthesis of a well-defined bifunctional dendrimer with 108 termini bearing 54 NO-releasing groups and 54 UDCA units (Dendri-(NO/UDCA)₅₄). For comparison, a lower-generation dendrimer bearing 18 NO-releasing groups and 18 UDCA units (Dendri-(NO/UDCA)₁₈) was also synthesized. The anti-inflammatory activity of these dendrimers was evaluated, showing that the bifunctional dendrimers have an inverse correlation between concentration and anti-inflammatory activity, with an effect dramatically pronounced for Dendri-(NO/UDCA)₅₄ 20, which at just 0.25 nM inhibited 76.1% of IL-8 secretion. Data suggest that nanomolar concentrations of these dendrimers aid in releasing NO in a safe and controlled way. This bifunctional dendrimer has great potential as a drug against multifactorial diseases associated with inflammatory processes.

Norbornene and Related Structures as Scaffolds in the Search for New Cancer Treatments

The norbornene scaffold has arisen as a promising structure in medicinal chemistry due to its possible therapeutic application in cancer treatment. The development of norbornene-based derivatives as potential chemotherapeutic agents is attracting significant attention. Here, we report an unprecedented review on the recent advances of investigations into the antitumoral efficacy of different compounds, including the abovementioned bicyclic scaffold in their structure, in combination with chemotherapeutic agents or forming metal complexes. The impact that structural modifications to these bicyclic compounds have on the antitumoral properties and the mechanisms by which these norbornene derivatives act are discussed in this review. In addition, the use of norbornene, and its related compounds, encapsulation in nanosystems for its use in cancer therapies is here detailed.

Sulfonated Block Copolymers: Synthesis, Chemical Modification, Self-Assembly Morphologies, and Recent Applications

Scientific research based on the self-assembly behavior of block copolymers (BCs) comprising charged-neutral segments has emerged as a novel strategy mainly looking for the optimization of efficiency in the generation and storage of electrical energy. The sulfonation reaction re- presents one of the most commonly employed methodologies by scientific investigations to reach the desired amphiphilic character, leading to enough ion concentration to modify and control the entire self-assembly behavior of the BCs. Recently, several works have studied and exploited these changes, inducing improvement on the mechanical properties, ionic conduction capabilities, colloidal solubility, interface activity, and stabilization of dispersed particles, among others. This review aims to present a description of recent works focused on obtaining amphiphilic block copolymers, specifically those that were synthesized by a living/controlled polymerization method and that have introduced the amphiphilic character by the sulfonation of one of the segments. Additionally, relevant works that have evidenced morphological and/or structural changes regarding the pristine BC as a result of the chemical modification are discussed. Finally, several emerging practical applications are analyzed to highlight the main drawbacks and challenges that should be addressed to overcome the development and understanding of these complex systems.

Advances in design of polymer brush functionalized inorganic nanomaterials and their applications in biomedical arena

Grafting of polymer brush (assembly of polymer chains tethered to the substrate by one end) is emerging as one of the most viable approach to alter the surface of inorganic nanomaterials. Inorganic nanomaterials despite their intrinsic functional superiority, their applications remain restricted due to their incompatibility with organic or biological moieties vis-à-vis agglomeration issues. To overcome such a shortcoming, polymer brush modified surfaces of inorganic nanomaterials have lately proved to be of immense potential. For example, polymer brush-modified inorganic nanomaterials can act as efficient substrates/platforms in biomedical applications, ranging from drug-delivery to protein-array due to their integrated advantages such as amphiphilicity, stimuli responsiveness, enhanced biocompatibility, and so on. In this review, the current state of the art related to polymer brush-modified inorganic nanomaterials focusing, not only, on their synthetic strategies and applications in biomedical field but also the architectural influence of polymer brushes on the responsiveness properties of modified nanomaterials have comprehensively been discussed and its associated future perspective is also presented. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Construction of Enzyme-Responsive Micelles Based on Theranostic Zwitterionic Conjugated Bottlebrush Copolymers with Brush-on-Brush Architecture for Cell Imaging and Anticancer Drug Delivery

Bottlebrush copolymers with different chemical structures and compositions as well as diverse architectures represent an important kind of material for various applications, such as biomedical devices. To our knowledge, zwitterionic conjugated bottlebrush copolymers integrating fluorescence imaging and tumor microenvironment-specific responsiveness for efficient intracellular drug release have been rarely reported, likely because of the lack of an efficient synthetic approach. For this purpose, in this study, we reported the successful preparation of well-defined theranostic zwitterionic bottlebrush copolymers with unique brush-on-brush architecture. Specifically, the bottlebrush copolymers were composed of a fluorescent backbone of polyfluorene derivate (PFONPN) possessing the fluorescence resonance energy transfer with doxorubicin (DOX), primary brushes of poly(2-hydroxyethyl methacrylate) (PHEMA), and secondary graft brushes of an enzyme-degradable polytyrosine (PTyr) block as well as a zwitterionic poly(oligo (ethylene glycol) monomethyl ether methacrylate-co-sulfobetaine methacrylate) (P(OEGMA-co-SBMA)) chain with super hydrophilicity and highly antifouling ability via elegant integration of Suzuki coupling, NCA ROP and ATRP techniques. Notably, the resulting bottlebrush copolymer, PFONPN9-g-(PHEMA15-g-(PTyr16-b-P(OEGMA6-co-SBMA6)2)) (P2) with a lower MW ratio of the hydrophobic side chains of PTyr and hydrophilic side chains of P(OEGMA-co-SBMA) could self-assemble into stabilized unimolecular micelles in an aqueous phase. The resulting unimolecular micelles showed a fluorescence quantum yield of 3.9% that is mainly affected by the pendant phenol groups of PTyr side chains and a drug-loading content (DLC) of approximately 15.4% and entrapment efficiency (EE) of 90.6% for DOX, higher than the other micelle analogs, because of the efficient supramolecular interactions of π–π stacking between the PTyr blocks and drug molecules, as well as the moderate hydrophilic chain length. The fluorescence of the PFONPN backbone enables fluorescence resonance energy transfer (FRET) with DOX and visualization of intracellular trafficking of the theranostic micelles. Most importantly, the drug-loaded micelles showed accelerated drug release in the presence of proteinase K because of the enzyme-triggered degradation of PTyr blocks and subsequent deshielding of P(OEGMA-co-SBMA) corona for micelle destruction. Taken together, we developed an efficient approach for the synthesis of enzyme-responsive theranostic zwitterionic conjugated bottlebrush copolymers with a brush-on-brush architecture, and the resulting theranostic micelles with high DLC and tumor microenvironment-specific responsiveness represent a novel nanoplatform for simultaneous cell image and drug delivery.

Synthesis of enzyme-responsive theranostic amphiphilic conjugated bottlebrush copolymers for enhanced anticancer drug delivery

Synthesis of polyfluorene (PF) based theranostic amphiphilic copolymers with simultaneously high drug loading efficiency and tumor microenvironment-specific responsiveness for promoted intracellular drug release and enhanced cancer therapy has been rarely reported likely due to the lack of efficient synthetic approaches to integrate these desirable properties. In this work, we recorded the successful preparation of well-defined theranostic amphiliphilic bottlebrush copolymers composing of fluorescent backbone of PF and tunable enzyme-degradable side chains of polytyrosine (PTyr) and POEGMA by integrating Suzuki coupling, NCA ROP and ATRP techniques. Notably, the resulting copolymer, PF₂₅-g-(PTyr₂₆-b-(POEGMA₂₈)₂ (P₄) with two branched POEGMA brushes tethered to one PTyr termini for each unit could form steady unimolecular micelles with higher fluorescence quantum yield of 18.3% in aqueous and greater entrapment efficiency (EE) of 91.0% for DOX ascribed to the efficient π-π stacking interactions between PTyr blocks and drug molecules and the unique structure of branched hydrophilic brushes with a moderate chain length. DOX@P₄ micelles revealed visualization of intracellular trafficking and accelerated drug release due to the enzyme-triggered degradation of PTyr blocks with proteinase K and subsequent deshielding of POEGMA corona for micelle destruction. In vitro and In vivo animal study further verified the intensive therapeutic efficiency with attenuated systematic toxicity. Taken together, we provided a universal strategy toward multifunctional polymeric delivery vehicles based on conjugated PF and biocompatible and degradable polypeptide by integratied Suzuki coupling and NCA ROP, and identified the branched structure of hydrophilic brushes for better performance of bottlebrush copolymers-based micelles for drug delivery applications. STATEMENT OF SIGNIFICANCE: Synthesis of polyfluorene (PF)-based theranostic amphiphilic copolymers with simultaneously high drug loading efficiency and tumor microenvironment-specific responsiveness for promoted intracellular drug release and enhanced cancer therapy has been rarely reported likely due to the lack of efficient synthetic approaches to integrate these desirable properties. We reported herein successful preparation of enzyme-responsive theranostic amphiliphilic bottlebrush copolymers with simultaneously high drug loading efficiency and tumor microenvironment-specific responsiveness for enhanced chemotherapy in vivo. This study therefore not only developed a universal strategy for the construction of multifunction polymeric vehicles based on the conjugated polymer of PF and degradable polypeptide by integrated Suzuki coupling and NCA ROP, but also emphasized the better stability of micelles endowed by the branched hydrophilic brushes than linear ones.

Molecular polymer bottlebrushes in nanomedicine: therapeutic and diagnostic applications

Molecular polymer bottlebrushes are densely grafted, individual macromolecules with nanoscale proportions. The last decade has seen an increased focus on this material class, especially in nanomedicine and for biomedical applications. This Feature Article provides an overview of major developments in this area to highlight the many opportunities that these polymer architectures bring to nano-bio research. The article covers aspects of bottlebrush synthesis and summarises their use in drug and gene delivery, imaging, as theranostics and as prototype materials to correlate nanoparticle structure and composition to biological function and behaviour. Areas for future research in this area are discussed.