Efficient Way to Generate Protein-Based Nanoparticles by in-Situ Photoinitiated Polymerization-Induced Self-Assembly

Degradable Block Copolymer Nanoparticles Synthesized by Polymerization-Induced Self-Assembly

Polymerization-induced self-assembly (PISA) combines polymerization and in situ self-assembly of block copolymers in one system and has become a widely used method to prepare block copolymer nanoparticles at high concentrations. The persistence of polymers in the environment poses a huge threat to the ecosystem and represents a significant waste of resources. There is an urgent need to develop novel chemical approaches to synthesize degradable polymers. To meet with this demand, it is crucial to install degradability into PISA nanoparticles. Most recently, degradable PISA nanoparticles have been synthesized by introducing degradation mechanisms into either shell-forming or core-forming blocks. This Minireview summarizes the development in degradable block copolymer nanoparticles synthesized by PISA, including shell-degradable, core-degradable, and all-degradable nanoparticles. Future development will benefit from expansion of polymerization techniques with new degradation mechanisms and adaptation of high-throughput approaches for both PISA syntheses and degradation studies.

Polymerization-Induced Self-Assembly: An Emerging Tool for Generating Polymer-Based Biohybrid Nanostructures

The combination of biomolecules and synthetic polymers provides an easy access to utilize advantages from both the synthetic world and nature. This is not only important for the development of novel innovative materials, but also promotes the application of biomolecules in various fields including medicine, catalysis, and water treatment, etc. Due to the rapid progress in synthesis strategies for polymer nanomaterials and deepened understanding of biomolecules' structures and functions, the construction of advanced polymer-based biohybrid nanostructures (PBBNs) becomes prospective and attainable. Polymerization-induced self-assembly (PISA), as an efficient and versatile technique in obtaining polymeric nano-objects at high concentrations, has demonstrated to be an attractive alternative to existing self-assembly procedures. Those advantages induce the focus on the fabrication of PBBNs via the PISA technique. In this review, current preparation strategies are illustrated based on the PISA technique for achieving various PBBNs, including grafting-from and grafting-through methods, as well as encapsulation of biomolecules during and subsequent to the PISA process. Finally, advantages and drawbacks are discussed in the fabrication of PBBNs via the PISA technique and obstacles are identified that need to be overcome to enable commercial application.

(Bio)degradable and Biocompatible Nano-Objects from Polymerization-Induced and Crystallization-Driven Self-Assembly

Polymerization-induced self-assembly (PISA) and crystallization-driven self-assembly (CDSA) techniques have emerged as powerful approaches to produce a broad range of advanced synthetic nano-objects with high potential in biomedical applications. PISA produces nano-objects of different morphologies (e.g., spheres, vesicles and worms), with high solids content (∼10-50 wt %) and without additional surfactant. CDSA can finely control the self-assembly of block copolymers and readily forms nonspherical crystalline nano-objects and more complex, hierarchical assemblies, with spatial and dimensional control over particle length or surface area, which is typically difficult to achieve by PISA. Considering the importance of these two assembly techniques in the current scientific landscape of block copolymer self-assembly and the craze for their use in the biomedical field, this review will focus on the advances in PISA and CDSA to produce nano-objects suitable for biomedical applications in terms of (bio)degradability and biocompatibility. This review will therefore discuss these two aspects in order to guide the future design of block copolymer nanoparticles for future translation toward clinical applications.

RAFT-mediated polymerization-induced self-assembly (RAFT-PISA): current status and future directions

Polymerization-induced self-assembly (PISA) combines polymerization and self-assembly in a single step with distinct efficiency that has set it apart from the conventional solution self-assembly processes. PISA holds great promise for large-scale production, not only because of its efficient process for producing nano/micro-particles with high solid content, but also thanks to the facile control over the particle size and morphology. Since its invention, many research groups around the world have developed new and creative approaches to broaden the scope of PISA initiations, morphologies and applications, etc. The growing interest in PISA is certainly reflected in the increasing number of publications over the past few years, and in this review, we aim to summarize these recent advances in the emerging aspects of RAFT-mediated PISA. These include (1) non-thermal initiation processes, such as photo-, enzyme-, redox- and ultrasound-initiation; the achievements of (2) high-order structures, (3) hybrid materials and (4) stimuli-responsive nano-objects by design and adopting new monomers and new processes; (5) the efforts in the realization of upscale production by utilization of high throughput technologies, and finally the (6) applications of current PISA nano-objects in different fields and (7) its future directions.

Polymer-hybrid nanosystems for antiviral applications: Current advances

The emergence of many new viruses in recent times has resulted in a significant scientific challenge for discovering drugs and vaccines that effectively treat and prevent viral diseases. Nanotechnology has opened doors to prevent the spread of several diseases, including those caused by viruses. Polymer-hybrid nanodevices are a class of nanotechnology platforms for biomedical applications that present synergistic properties among their components, with improved performance compared to conventional forms of therapy. Considering the growing interest in this emerging field and the promising technological advantages of polymer-hybrid nanodevices, this work presents the current status of these systems in the context of prevention and treatment of viral diseases. A brief description of the different types of polymer-hybrid nanodevices highlighting some peculiar characteristics such as their composition, biodistribution, delivery of antigens, and overall immune responses in systemic tissues are discussed. Finally, the work presents the future trends for new nanotechnological hybrid materials based on polymers and perspectives for clinical use.

Protein-, (Poly)peptide-, and Amino Acid-Based Nanostructures Prepared via Polymerization-Induced Self-Assembly

Proteins and peptides, built from precisely defined amino acid sequences, are an important class of biomolecules that play a vital role in most biological functions. Preparation of nanostructures through functionalization of natural, hydrophilic proteins/peptides with synthetic polymers or upon self-assembly of all-synthetic amphiphilic copolypept(o)ides and amino acid-containing polymers enables access to novel protein-mimicking biomaterials with superior physicochemical properties and immense biorelevant scope. In recent years, polymerization-induced self-assembly (PISA) has been established as an efficient and versatile alternative method to existing self-assembly procedures for the reproducible development of block copolymer nano-objects in situ at high concentrations and, thus, provides an ideal platform for engineering protein-inspired nanomaterials. In this review article, the different strategies employed for direct construction of protein-, (poly)peptide-, and amino acid-based nanostructures via PISA are described with particular focus on the characteristics of the developed block copolymer assemblies, as well as their utilization in various pharmaceutical and biomedical applications.

New Light in Polymer Science: Photoinduced Reversible Addition-Fragmentation Chain Transfer Polymerization (PET-RAFT) as Innovative Strategy for the Synthesis of Advanced Materials

Photochemistry has attracted great interest in the last decades in the field of polymer and material science for the synthesis of innovative materials. The merging of photochemistry and reversible-deactivation radical polymerizations (RDRP) provides good reaction control and can simplify elaborate reaction protocols. These advantages open the doors to multidisciplinary fields going from composite materials to bio-applications. Photoinduced Electron/Energy Transfer Reversible Addition-Fragmentation Chain-Transfer (PET-RAFT) polymerization, proposed for the first time in 2014, presents significant advantages compared to other photochemical techniques in terms of applicability, cost, and sustainability. This review has the aim of providing to the readers the basic knowledge of PET-RAFT polymerization and explores the new possibilities that this innovative technique offers in terms of industrial applications, new materials production, and green conditions.

Oxygen tolerant, photoinduced controlled radical polymerization approach for the synthesis of giant amphiphiles

New families of amphiphilic protein–polymer bioconjugates readily synthesized via an oxygen tolerant, photoinduced RDRP approach.

Non-thermally initiated RAFT polymerization-induced self-assembly

This review summarizes the recent non-thermal initiation methods in RAFT mediated polymerization-induced self-assembly (PISA), including photo-, redox/oscillatory reaction-, enzyme- and ultrasound wave-initiation.

Dual Role of Doxorubicin for Photopolymerization and Therapy

In this study, we report dual roles for doxorubicin (DOX), which can serve as an antitumor drug as well as a cocatalyst for a photoliving radical polymerization. DOX enhances the polymerization rates of a broad range of monomers, including acrylamide, acrylate, and methacrylates, allowing for high monomer conversion and well-defined molecular weights under irradiation with a blue light-emitting diode light (λ_max = 485 nm, 2.2 mW/cm²). Utilizing this property, the photopolymerization of N,N-diethylacrylamide was performed in the presence of a poly(oligo(ethylene glycol) methyl ether acrylate) macroreversible addition-fragmentation chain transfer (macroRAFT) agent to prepare polymeric nanoparticles via aqueous polymerization-induced self-assembly (PISA). By varying the monomer:macroRAFT ratio, spherical polymeric nanoparticles of various diameters could be produced. Most notably, DOX was successfully encapsulated into the hydrophobic core of nanoparticles during the PISA process. The DOX-loaded nanoparticles were effectively uptaken into tumor cells and significantly inhibited the proliferation of tumor cells, demonstrating that the DOX bioactivity was not affected by the polymerization reaction.

Polypyrrole and polyaniline nanocomposites with high photothermal conversion efficiency

The simple and scalable synthesis of poly[2-(methacryloyloxy)ethyl phosphorylcholine] (PMPC)-coated conducting polymer (CP) nanocomposites is described. These functional nanocomposites exhibit tunable absorption in the near-infrared region with relatively high photothermal efficiencies. More importantly, their potential for bio-imaging and therapeutic treatment is proven by cellular uptake and cytotoxicity studies.

Enlightening advances in polymer bioconjugate chemistry: light-based techniques for grafting to and from biomacromolecules

Photochemistry has revolutionized the field of polymer-biomacromolecule conjugation. Ligation reactions necessitate biologically benign conditions, and photons have a significant energy advantage over what is available thermally at ambient temperature, allowing for rapid and unique reactivity. Photochemical reactions also afford many degrees of control, specifically, spatio-temporal control, light source tunability, and increased oxygen tolerance. Light-initiated polymerizations, in particular photo-atom-transfer radical polymerization (photo-ATRP) and photoinduced electron/energy transfer reversible addition-fragmentation chain transfer polymerization (PET-RAFT), have been used for grafting from proteins, DNA, and cells. Additionally, the spatio-temporal control inherent to light-mediated chemistry has been utilized for grafting biomolecules to hydrogel networks for many applications, such as 3-D cell culture. While photopolymerization has clear advantages, there are factors that require careful consideration in order to obtain optimal control. These factors include the photocatalyst system, light intensity, and wavelength. This Perspective aims to discuss recent advances of photochemistry for polymer biomacromolecule conjugation and potential considerations while tailoring these systems.

Cross-linking approaches for block copolymer nano-assemblies via RAFT-mediated polymerization-induced self-assembly

This minireview summarizes the current cross-linking approaches to stabilize block copolymer nano-assemblies obtained via RAFT-mediated PISA process.

Synthesis of lipase–polymer conjugates by Cu(0)-mediated reversible deactivation radical polymerization: polymerization vs. degradation

Cu(0)-RDRP was first used for the polymerization-induced self-assembly of lipase–polymer conjugates, inducing the formation of nanospheres with preserved activity and degradability.

100th Anniversary of Macromolecular Science Viewpoint: Heterogenous Reversible Deactivation Radical Polymerization at Room Temperature. Recent Advances and Future Opportunities

Heterogenous reversible deactivation radical polymerization (RDRP) has become an important method for the preparation of a diverse set of well-defined polymer materials in dispersed systems. Conducting heterogeneous RDRP at room temperature seems to be a minor adjustment in polymerization technique but this will lead to a great opportunity for functional polymer synthesis, developing of interesting heterogeneous RDRP systems, and better mechanistic insights into heterogeneous RDRP. In this Viewpoint, we highlight some recent advances of room-temperature heterogeneous RDRP that are challenging to achieve via traditional thermally initiated heterogeneous RDRP. We hope that this Viewpoint can provide some inspiration for both experts in this field and new comers, as well as nonexperts who are interested in preparing their own polymer materials by conducting room-temperature heterogeneous RDRP.

Emerging Trends in Polymerization-Induced Self-Assembly

In this Perspective, we summarize recent progress in polymerization-induced self-assembly (PISA) for the rational synthesis of block copolymer nanoparticles with various morphologies. Much of the PISA literature has been based on thermally initiated reversible addition-fragmentation chain transfer (RAFT) polymerization. Herein, we pay particular attention to alternative PISA protocols, which allow the preparation of nanoparticles with improved control over copolymer morphology and functionality. For example, initiation based on visible light, redox chemistry, or enzymes enables the incorporation of sensitive monomers and fragile biomolecules into block copolymer nanoparticles. Furthermore, PISA syntheses and postfunctionalization of the resulting nanoparticles (e.g., cross-linking) can be conducted sequentially without intermediate purification by using various external stimuli. Finally, PISA formulations have been optimized via high-throughput polymerization and recently evaluated within flow reactors for facile scale-up syntheses.

Controlling the Self-Assembly of Biomolecules into Functional Nanomaterials through Internal Interactions and External Stimulations: A Review

Biomolecular self-assembly provides a facile way to synthesize functional nanomaterials. Due to the unique structure and functions of biomolecules, the created biological nanomaterials via biomolecular self-assembly have a wide range of applications, from materials science to biomedical engineering, tissue engineering, nanotechnology, and analytical science. In this review, we present recent advances in the synthesis of biological nanomaterials by controlling the biomolecular self-assembly from adjusting internal interactions and external stimulations. The self-assembly mechanisms of biomolecules (DNA, protein, peptide, virus, enzyme, metabolites, lipid, cholesterol, and others) related to various internal interactions, including hydrogen bonds, electrostatic interactions, hydrophobic interactions, π⁻π stacking, DNA base pairing, and ligand⁻receptor binding, are discussed by analyzing some recent studies. In addition, some strategies for promoting biomolecular self-assembly via external stimulations, such as adjusting the solution conditions (pH, temperature, ionic strength), adding organics, nanoparticles, or enzymes, and applying external light stimulation to the self-assembly systems, are demonstrated. We hope that this overview will be helpful for readers to understand the self-assembly mechanisms and strategies of biomolecules and to design and develop new biological nanostructures or nanomaterials for desired applications.

Interfacial self-assembly of gold nanoparticle-polymer nanoconjugates into microcapsules with near-infrared light modulated biphasic catalysis efficiency

Gold nanoparticle-based microcapsules based on the interfacial assembly significantly enhanced the biphasic catalytic reaction rate upon near-infrared light irradiation.

Exploiting Wavelength Orthogonality for Successive Photoinduced Polymerization-Induced Self-Assembly and Photo-Crosslinking

We report a facile benchtop process for the synthesis of cross-linked polymeric nanoparticles by exploiting wavelength-selective photochemistry to perform orthogonal photoinduced polymerization-induced self-assembly (Photo-PISA) and photo-crosslinking processes. We first established that the water-soluble photocatalyst, zinc meso-tetra(N-methyl-4-pyridyl) porphine tetrachloride (ZnTMPyP) could activate the aqueous PET-RAFT dispersion polymerization of hydroxypropyl methacrylate (HPMA). This photo-PISA process could be conducted under low energy red light (λ_max = 595 nm, 10.2 mW/cm²) and without deoxygenation due to the action of the singlet oxygen quencher, biotin (vitamin B₇), which allowed for the synthesis of a range of nanoparticle morphologies (spheres, worms, and vesicles) directly in 96-well plates. To perform wavelength selective nanoparticle cross-linking, we added the photoresponsive monomer, 7-[4-(trifluoromethyl)coumarin] methacrylamide (TCMAm) as a comonomer without inhibiting the evolution of the nanoparticle morphology. Importantly, under red light, exclusive activation of the photo-PISA process occurs, with no evidence of TCMAm dimerization under these conditions. Subsequent switching to a UV source (λ_max = 365 nm, 10.2 mW/cm²) resulted in rapid cross-linking of the polymer chains, allowing for retention of the nanoparticle morphology in organic solvents. This facile synthesis of cross-linked spheres, worms, and vesicles demonstrates the utility of orthogonal light-mediated chemistry for performing decoupled wavelength selective chemical processes.

Photochemistry for Well-Defined Polymers in Aqueous Media: From Fundamentals to Polymer Nanoparticles to Bioconjugates

This review article highlights recent developments in the field of photochemistry and photochemical reversible deactivation radical polymerization applied to aqueous polymerizations. Photochemistry is a topic of significant interest in the fields of organic, polymer, and materials chemistry because it allows challenging reactions to be performed under mild conditions. Aqueous polymerization is of significant interest because water is an environmentally benign solvent, and the use of water enables complex polymer self-assembly and bioconjugation processes to occur. This review focuses on powerful new developments in photochemical aqueous polymerization reactions and their applications to the synthesis of well-defined polymer nano-objects and bioconjugates. It is anticipated that these aqueous photopolymerizations will enable the next generation of self-assembled structures and biohybrid materials to be developed under mild and environmentally friendly conditions.

PET-RAFT polymerisation: towards green and precision polymer manufacturing

Photoinduced electron/energy transfer-reversible addition–fragmentation chain transfer (PET-RAFT) process has opened up a new way of precision polymer manufacturing to satisfy the concept of green chemistry.

Photocontrolled protein assembly for constructing programmed two-dimensional nanomaterials

A rapid and efficient strategy was developed to construct photocontrolled 2D protein nanosheets with an orderly arrangement.

Permeable Protein-Loaded Polymersome Cascade Nanoreactors by Polymerization-Induced Self-Assembly

Enzyme loading of polymersomes requires permeability to enable them to interact with the external environment, typically requiring addition of complex functionality to enable porosity. Herein, we describe a synthetic route towards intrinsically permeable polymersomes loaded with functional proteins using initiator-free visible light-mediated polymerization-induced self-assembly (photo-PISA) under mild, aqueous conditions using a commercial monomer. Compartmentalization and retention of protein functionality was demonstrated using green fluorescent protein as a macro-molecular chromophore. Catalytic enzyme-loaded vesicles using horseradish peroxidase and glucose oxidase were also prepared and the permeability of the membrane towards their small molecule substrates was revealed for the first time. Finally, the interaction of the compartmentalized enzymes between separate vesicles was validated by means of an enzymatic cascade reaction. These findings have a broad scope as the methodology could be applied for the encapsulation of a large range of macromolecules for advancements in the fields of nanotechnology, biomimicry and nanomedicine.

Construction of polymer coated core–shell magnetic mesoporous silica nanoparticles with triple responsive drug delivery

Multi-responsive drug delivery systems are playing a very important role in nanomedicine, as they can feature as smart carriers releasing their payload on demand.