Biocompatible Polymer Nano-Constructs: A Potent Platform for Cancer Theranostics

Nano-constructs of biocompatible polymers have drawn wide attention owing to their potential as theranostics for simultaneous therapy and detection of cancer. The present mini review summarizes various nano-architectures of polymers that have been developed as theranostic agents for the simultaneous treatment and diagnosis of cancer in a single platform. Additionally, research prospects of polymeric cancer theranostics for the future have been highlighted.

Curcumin-Loaded Oil-Free Self-Assembled Micelles Inhibit the Influenza A Virus Activity and the Solidification of Curcumin-Loaded Micelles for Pharmaceutical Applications

Curcumin, a well-known natural lipophilic phenolic compound, plays a vital role in inhibiting the influenza infection. Currently, many kinds of formulations for the enhancement of a water dispersion of curcumin have been developed; however, the anti-influenza abilities of formulated curcumin have been much less investigated. In this study, the optimized self-assembled micelles of RH 40/Tween 80 loaded with curcumin (Cur-M) in an oil-free-based system were spherical with a hydrodynamic size at 13.55 nm ± 0.208 and polydispersity at 0.144 characterized by atomic force microscopy and dynamic light scattering, respectively. Additionally, Cur-M significantly increased the bioactivity/stability of curcumin and effectively inhibited the influenza A virus infection and its replication after viral entry, indicating the alteration of the inhibition mechanisms of curcumin against virus infection via RH 40/Tween 80 micelle formulation. Furthermore, a solid formulation (Cur-SM) of Cur-M was successfully developed by a one-pot physical adsorption method using a small amount of adsorbent and ~50% of curcumin/Cur-M that could be burst released from Cur-SM in 1 h, facilitating the fast-releasing applications. Ultimately, all of the results show that Cur-SM acts as a good nano-formulation of curcumin with improved solubility/dispersity in aqueous solutions and demonstrate new anti-influenza mechanisms of curcumin for pharmaceutical development.

Light-Triggered Polymersome-Based Anticancer Therapeutics Delivery

Polymersomes are biomimetic cell membrane-like model structures that are self-assembled stepwise from amphiphilic copolymers. These polymeric (nano)carriers have gained the scientific community's attention due to their biocompatibility, versatility, and higher stability than liposomes. Their tunable properties, such as composition, size, shape, and surface functional groups, extend encapsulation possibilities to either hydrophilic or hydrophobic cargoes (or both) and their site-specific delivery. Besides, polymersomes can disassemble in response to different stimuli, including light, for controlling the "on-demand" release of cargo that may also respond to light as photosensitizers and plasmonic nanostructures. Thus, polymersomes can be spatiotemporally stimulated by light of a wide wavelength range, whose exogenous response may activate light-stimulable moieties, enhance the drug efficacy, decrease side effects, and, thus, be broadly employed in photoinduced therapy. This review describes current light-responsive polymersomes evaluated for anticancer therapy. It includes light-activable moieties' features and polymersomes' composition and release behavior, focusing on recent advances and applications in cancer therapy, current trends, and photosensitive polymersomes' perspectives.

Modification of Oligo- and Polylactides With Macrocyclic Fragments: Synthesis and Properties

Products of lactic acid polycondensation (poly- and oligolactic acids) are widely used as packaging materials, drug delivery agents, implants etc. Variety of their applications is caused by a number of practically important properties, e.g., biocompatibility and biodegradability, non-toxicity, and mechanical durability. Modification of these polymers with different additives allows improving their properties and extending future applications. In this manner, stability toward degradation, recognition of some substrates, extended thermal stability etc. can be improved. Macrocyclic compounds are promising candidates as modifiers. They are able to provide polymer materials with additional binding sites, impart certain orientation to spatial arrangement of polymer chains, change hydrophilic-lipophilic balance, and redox properties. The latter one can be used for assembling various electrochemical sensors and biosensors that combine steric discrimination of the analytes caused by oligolactides and highly sensitive response to their quantities caused by redox labels introduced. Different composite materials based on oligolactides as matrices for such redox labels were described in the assemblies of biosensors for drugs, pesticides, and antioxidants detection. In this mini-review, methods for the synthesis of the lactic acid oligomers and those modified with the macrocyclic fragments (porphyrin, cyclodextrin, and cyclophane) have been described. The effects of modifiers on complexation, thermal, and aggregation properties of materials are described. Analytical performance of oligolactide based sensors and biosensors has been considered with particular emphasis to the mechanism of signal generation.

Stimulus-responsive vesicular polymer nano-integrators for drug and gene delivery

Over the past two decades, nano-sized biosystems have increasingly been utilized to deliver various pharmaceutical agents to a specific region, organ or tissue for controllable precision therapy. Whether solid nanohydrogel, nanosphere, nanoparticle, nanosheet, micelles and lipoproteins, or "hollow" nanobubble, liposome, nanocapsule, and nanovesicle, all of them can exhibit outstanding loading and releasing capability as a drug vehicle - in particular polymeric nanovesicle, a microscopic hollow sphere that encloses a water core with a thin polymer membrane. Besides excellent stability, toughness and liposome-like compatibility, polymeric nanovesicles offer considerable scope for tailoring properties by changing their chemical structure, block lengths, stimulus-responsiveness and even conjugation with biomolecules. In this review, we summarize the latest advances in stimulus-responsive polymeric nanovesicles for biomedical applications. Different functionalized polymers are in development to construct more complex multiple responsive nanovesicles in delivery systems, medical imaging, biosensors and so on.

Enhanced Antitumor Effects of Epidermal Growth Factor Receptor Targetable Cetuximab-Conjugated Polymeric Micelles for Photodynamic Therapy

Nanocarrier-based delivery systems are promising strategies for enhanced therapeutic efficacy and safety of toxic drugs. Photodynamic therapy (PDT)—a light-triggered chemical reaction that generates localized tissue damage for disease treatments—usually has side effects, and thus patients receiving photosensitizers should be kept away from direct light to avoid skin phototoxicity. In this study, a clinically therapeutic antibody cetuximab (C225) was conjugated to the surface of methoxy poly(ethylene glycol)-b-poly(lactide) (mPEG-b-PLA) micelles via thiol-maleimide coupling to allow tumor-targetable chlorin e6 (Ce6) delivery. Our results demonstrate that more C225-conjugated Ce6-loaded polymeric micelles (C225-Ce6/PM) were selectively taken up than Ce6/PM or IgG conjugated Ce6/PM by epidermal growth factor receptor (EGFR)-overexpressing A431 cells observed by confocal laser scanning microscopy (CLSM), thereby decreasing the IC₅₀ value of Ce6-mediated PDT from 0.42 to 0.173 μM. No significant differences were observed in cellular uptake study or IC₅₀ value between C225-Ce6/PM and Ce6/PM groups in lower EGFR expression HT-29 cells. For antitumor study, the tumor volumes in the C225-Ce6/PM-PDT group (percentage of tumor growth inhibition, TGI% = 84.8) were significantly smaller than those in the Ce6-PDT (TGI% = 38.4) and Ce6/PM-PDT groups (TGI% = 53.3) (p < 0.05) at day 21 through reduced cell proliferation in A431 xenografted mice. These results indicated that active EGFR targeting of photosensitizer-loaded micelles provides a possible way to resolve the dose-limiting toxicity of conventional photosensitizers and represents a potential delivery system for PDT in a clinical setting.

Marine natural pigments as potential sources for therapeutic applications

In recent years, marine natural pigments have emerged as a powerful alternative in the various fields of food, cosmetic, and pharmaceutical industries because of their excellent biocompatibility, bioavailability, safety, and stability. Marine organisms are recognized as a rich source of natural pigments such as chlorophylls, carotenoids, and phycobiliproteins. Numerous studies have shown that marine natural pigments have considerable medicinal potential and promising applications in human health. In this review, we summarize the marine natural pigments as potential sources for therapeutic applications, including: antioxidant, anticancer, antiangiogenic, anti-obesity, anti-inflammatory activities, drug delivery, photothermal therapy (PTT), photodynamic therapy (PDT), photoacoustic imaging (PAI), and wound healing. Marine natural pigments will offer a better platform for future theranostic applications.

Advanced Functional Nanomaterials for Theranostics

Nanoscale materials have been explored extensively as agents for therapeutic and diagnostic (i.e. theranostic) applications. Research efforts have shifted from exploring new materials in vitro to designing materials that function in more relevant animal disease models, thereby increasing potential for clinical translation. Current interests include non-invasive imaging of diseases, biomarkers and targeted delivery of therapeutic drugs. Here, we discuss some general design considerations of advanced theranostic materials and challenges of their use, from both diagnostic and therapeutic perspectives. Common classes of nanoscale biomaterials, including magnetic nanoparticles, quantum dots, upconversion nanoparticles, mesoporous silica nanoparticles, carbon-based nanoparticles and organic dye-based nanoparticles, have demonstrated potential for both diagnosis and therapy. Variations such as size control and surface modifications can modulate biocompatibility and interactions with target tissues. The needs for improved disease detection and enhanced chemotherapeutic treatments, together with realistic considerations for clinically translatable nanomaterials will be key driving factors for theranostic agent research in the near future.

Carrier-Free, Chemophotodynamic Dual Nanodrugs via Self-Assembly for Synergistic Antitumor Therapy

There are tremendous challenges from both tumor and its therapeutic formulations affecting the effective treatment of tumor, including tumor recurrence, and complex multistep preparations of formulation. To address these issues, herein a simple and green approach based on the self-assembly of therapeutic agents including a photosensitizer (chlorine e6, Ce6) and a chemotherapeutic agent (doxorubicin, DOX) was developed to prepare carrier-free nanoparticles (NPs) with the ability to inhibit tumor recurrence. The designed NPs were formed by self-assembly of Ce6 and DOX associated with electrostatic, π-π stacking and hydrophobic interactions. They have a relatively uniform size of average 70 nm, surface charge of -20 mV and high drug encapsulation efficiency, which benefits the favorable accumulation of drugs at the tumor region through a potential enhanced permeability and retention (EPR) effect as compared to their counterpart of free Ce6 solution. In addition, they could eradiate tumors without recurrence in a synergistic way following one treatment cycle. Furthermore, the NPs are safe without any activation of inflammation or immune response in separated organs. Taken together, the rationale of these pure nanodrugs via the self-assembly approach might open an alternative avenue and give inspiration to fabricate new carrier-free nanodrugs for tumor theranostics, especially for two small molecular antitumor drugs with the aim of combinational antitumor therapy in a synergistic way.

Stereocomplex-Reinforced PEGylated Polylactide Micelle for Optimized Drug Delivery

The instability of PEGylated polylactide micelles is a challenge for drug delivery. Stereocomplex interaction between racemic polylactide chains with different configurations provides an effective strategy to enhance the stability of micelles as the nanocarriers of drugs. In this work, a stereocomplex micelle (SCM) self-assembled from the amphiphilic triblock copolymers comprising poly(ethylene glycol) (PEG), and dextrorotatory and levorotatory polylactides (PDLA and PLLA) was applied for efficient drug delivery. The spherical SCM showed the smallest scale and the lowest critical micelle concentration (CMC) than the micelles with single components attributed to the stereocomplex interaction between PDLA and PLLA. 10-Hydroxycamptothecin (HCPT) as a model antitumor drug was loaded into micelles. Compared with the loading micelles from individual PDLA and PLLA, the HCPT-loaded SCM exhibited the highest drug loading efficiency (DLE) and the slowest drug release in phosphate-buffered saline (PBS) at pH 7.4, indicating its enhanced stability in circulation. More fascinatingly, the laden SCM was demonstrated to have the highest cellular uptake of HCPT and suppress malignant cells most effectively in comparison to the HCPT-loaded micelles from single copolymer. In summary, the stereocomplex-enhanced PLA⁻PEG⁻PLA micelle may be promising for optimized drug delivery in the clinic.

Facile synthesis of a multifunctional copolymer via a concurrent RAFT-enzymatic system for theranostic applications

Through a straightforward concurrent RAFT-enzymatic multicomponent polymerization system and subsequent post-polymerization modifications, a multi-functional copolymer for theranostic application has been efficiently prepared.

Aggregation behavior of tetraphenylporphyrin in aqueous surfactant solutions: Chiral premicellar J-aggregate formation

Porphyrin-surfactant interactions in aqueous solutions are known to result in the selfassembly of various supramolecular structures, including pigment-surfactant complexes, J- and H-aggregates, and solubilized dye species. Detailed studies on the mechanisms of the intermolecular interactions governing the above self-assembly processes allow to predict the aggregation state and hence, the photophysical properties of the dye-surfactant assemblies in order to perform a direct synthesis of the desired porphyrin-based nanostructures at the appropriate experimental conditions. This paper describes a novel example of the surfactant-induced J-aggregate formation from the diprotonated hydrophobic tetraphenylporphyrin species in submicellar aqueous anionic surfactant solutions. The above assemblies are characterized by a rod-like morphology and possess supramolecular chirality according to the CD measurements.

Photodynamic therapy: one step ahead with self-assembled nanoparticles

Photodynamic therapy (PDT) is a promising treatment modality for cancer with possible advantages over current treatment alternatives. It involves combination of light and a photosensitizer (PS), which is activated by absorption of specific wavelength light and creates local tissue damage through generation of reactive oxygen species (ROS) that induce a cascade of cellular and molecular events. However, as of today, PDT is still in need of improvement and nanotechnology may play a role. PDT frequently employs PS with molecular structures that are highly hydrophobic, water insoluble and prone to aggregation. Aggregation of PS leads to reduced ROS generation and thus lowers the PDT activity. Some PS such as 5-aminolevulinic acid (ALA) cannot penetrate through the stratum corneum of the skin and systemic administration is not an option due to frequently encountered side effects. Therefore PS are often encapsulated or conjugated in/on nano-drug delivery vehicles to allow them to be better taken up by cells and to more selectively deliver them to tumors or other target tissues. Several nano-drug delivery vehicles including liposomes, fullerosomes and nanocells have been tested and reviewed. Here we cover non-liposomal self-assembled nanoparticles consisting of polymeric micelles including block co-polymers, polymeric micelles, dendrimers and porphysomes.

Emerging applications of porphyrins in photomedicine

Biomedical applications of porphyrins and related molecules have been extensively pursued in the context of photodynamic therapy. Recent advances in nanoscale engineering have opened the door for new ways that porphyrins stand to potentially benefit human health. Metalloporphyrins are inherently suitable for many types of medical imaging and therapy. Traditional nanocarriers such as liposomes, dendrimers and silica nanoparticles have been explored for photosensitizer delivery. Concurrently, entirely new classes of porphyrin nanostructures are being developed, such as smart materials that are activated by specific biochemicals encountered at disease sites. Techniques have been developed that improve treatments by combining biomaterials with photosensitizers and functional moieties such as peptides, DNA and antibodies. Compared to simpler structures, these more complex and functional designs can potentially decrease side effects and lead to safer and more efficient phototherapies. This review examines recent research on porphyrin-derived materials in multimodal imaging, drug delivery, bio-sensing, phototherapy and probe design, demonstrating their bright future for biomedical applications.

Theranostic lipid nanoparticles for cancer medicine

Disease heterogeneity within and between patients necessitates a patient-focused approach to cancer treatment. This exigency forms the basis for the medical practice termed personalized medicine. An emerging, important component of personalized medicine is theranostics. Theranostics describes the co-delivery of therapeutic and imaging agents in a single formulation. Co-delivery enables noninvasive, real-time visualization of drug fate, including drug pharmacokinetic and biodistribution profiles and intratumoral accumulation. These technological advances assist drug development and ultimately may translate to improved treatment planning at the bedside. Nanocarriers are advantageous for theranostics as their size and versatility enables integration of multiple functional components in a single platform. This chapter focuses on recent developments in advanced lipid theranostic nanomedicine from the perspective of the "all-in-one" or the "one-for-all" approach. The design paradigm of "all-in-one" is the most common approach for assembling theranostic lipid nanoparticles, where the advantages of theranostics are achieved by combining multiple components that each possesses a specific singular function for therapeutic activity or imaging contrast. We will review lipoprotein nanoparticles and liposomes as representatives of the "all-in-one" approach. Complementary to the "all-in-one" approach is the emerging paradigm of the "one-for-all" approach where nanoparticle components are intrinsically multifunctional. We will discuss the "one-for-all" approach using porphysomes as a representative. We will further discuss how the concept of "one-for-all" might overcome the regulatory hurdles facing theranostic lipid nanomedicine.

Photodynamic therapy of oligoethylene glycol dendronized reduction-sensitive porphyrins

OEGylation of porphyrins via a disulfide linkage to form a novel class of dendritic porphyrin photosensitizers (PSs) is presented.

Star-shaped poly(l-lactide)-b-poly(ethylene glycol) with porphyrin core: synthesis, self-assembly, drug-release behavior and singlet oxygen research

pH-induced block copolymer SPPLA-b-PEG with porphyrin core for photodynamic therapy.

Synthesis, structural characterization and protonation/deprotonation of hydroxyl-substituted free-base tetraphenylporphyrins in nonaqueous media

A series of hydroxyl-substituted free-base tetraphenylporphyrins was synthesized and characterized by UV-vis spectroscopy, 1 H NMR and mass spectrometry. The porphyrins are represented as (HOPh) n(t BuPh )4-n PH 2, where Ph presents a phenyl group, HO and t Bu are substituents on the para-positions of the phenyl rings of the macrocycle, n = 0–4 and P represents the dianion of tetraphenylporphyrin. The UV-visible properties of each porphyrin were examined in dichloromethane (DCM), N,N′-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) before and after addition of trifluoroacetic acid (TFA) or sodium hydroxide (NaOH) to solution. Equilibrium constants for protonation ( log βn) and deprotonation [Formula: see text] of each compound were determined using standard equations. The protonations occur in a single step involving a simultaneous two proton addition at the porphyrin central nitrogens. The phenolic protons on (HOPh) n(t BuPh )4-n PH 2 are easier to deprotonate than the core nitrogen protons of the porphyrins and this reaction occurs in a single step involving the simultaneous loss of 1–4 protons on the hydroxyl groups followed by a loss of two protons from the central nitrogens. The effect of HO substituents on UV-visible spectra and the magnitude of the protonation/deprotonation constants ( log βn and [Formula: see text]) are discussed. Two of the porphyrins, (t BuPh )4 PH 2 and trans- (HOPh) 2(t BuPh )2 PH 2, are also characterized by a single-crystal X-ray analysis.

Polymeric theranostics: using polymer-based systems for simultaneous imaging and therapy

Polymer-based nanomedicine is a large and fast growing field. Polymer-based systems have been extensively used as therapeutic carriers as well as bioimaging agents for example in tumour diagnosis. However, fewer polymeric systems have been able to combine both therapy and imaging in a new field that is called theranostics (theragnostics). This review aims to summarise the recent developments and trends on polymeric theranostics. Four different types of therapies/treatments are examined namely drug delivery, gene delivery, photodynamic therapy and hyperthermia treatment combined with different imaging moieties like magnetic resonance imaging agents, fluorescent agents and microbubbles for ultrasound imaging.

Star-shaped polymer consisting of a porphyrin core and poly(L-lysine) dendron arms: synthesis, drug delivery, and in vitro chemo/photodynamic therapy

A novel star-shaped polymer, porphyrin-poly(L-lysine) dendrons (PP-PLLD), is synthesized by the click reaction between azido-modified porphyrin and propargyl focal point poly(L-lysine) dendrons. Its chemical structure is characterized by (1) H nuclear magnetic resonance, Fourier transform infrared spectroscopy, and gel permeation chromatography (GPC) is analyses etc. Due to its amphiphilic property, the obtained PP-PLLD has a low critical micelle concentration in an aqueous solution, and can load doxorubicin (DOX) with a loading amount of 64 μg mg(-1) . By in vitro toxicity assay, PP-PLLD has no dark cytotoxicity but has significant phototoxicity. Moreover, DOX-loaded PP-PLLD shows a higher cytotoxicity under the light condition than PP-PLLD or DOX alone, suggesting PP-PLLD has a potential application in combined photodynamic therapy and chemotherapy.

Effects of the Addition ofOrtho- andPara-NH2Substituted Tetraphenylporphyrins on the Structure of Nylon 66

The synthetic tetrapyrrole macrocycles, such as porphyrins (H2P) and phthalocyanines (H2Pc), exhibit interesting physicochemical properties suitable to be used in modern technology. For many applications, those species should be trapped or fixed inside graphite, hydrotalcites, silica, TiO2, or polymers. Methodologies for the optimization of the properties of porphyrins, trapped or fixed inside polymers, have been barely developed. Our research works in the development of methodologies for the optimization of incorporation and display of properties of tetrapyrrole macrocycles inside inorganic, polymeric, or hybrid networks. This paper shows some results about the effect of the spatial disposition of the amine (–NH2) groups attached on the periphery of substituted tetraphenylporphyrins, on the Nylon 66 structure and on the display of the physicochemical properties of the trapped macrocycles. Nylon 66 was synthesized from adipoyl chloride and hexamethylenediamine in presence of tetraphenylporphyrins substituted with –NH2groups localized at theortho- orpara-positions of the phenyls. Cobalt complexes formation was used to quantify the amount of porphyrins in the polymer fibers. Characterization results show that the spatial position of amine groups of the porphyrins has important structural and textural effect on the Nylon 66 fibers and on the fluorescence of the porphyrins integrated into the fibers.