Integrated prodrug micelles with two-photon bioimaging and pH-triggered drug delivery for cancer theranostics

In vivo dynamic visualization and evaluation of collagen degradation utilizing NIR-II fluorescence imaging in mice models

Collagen-based biomaterials are gaining prominence in tissue engineering, attributed to their remarkable biocompatibility, inherent biodegradability, and unparalleled capacity to facilitate tissue repair and regeneration. However, the ability to dynamically visualize and quantitatively assess collagen degradation in vivo remains a critical challenge, hindering the development of optimized biomaterials for clinical applications. To address this, a novel approach was developed to monitor the injury microenvironment by conjugating second near-infrared quantum dots with solid collagen. This live imaging system offered high-resolution, real-time tracking of collagen degradation both in vitro and in vivo, enabling a deeper understanding of the degradation behavior under various conditions. This system was applied to mouse models with different cartilage defects, including critical-sized defect (CSD), minor defect (Minor) and sham surgery (Sham) groups for a 28-day in vivo monitoring. Among them, the CSD group exhibited the fastest and most stable collagen degradation, indicating that the degradation rate was closely linked to the severity of the injury. Transcriptomic analysis further identified key signaling pathways that might drive rapid collagen degradation by promoting collagenase activity and tissue remodeling in cartilage defect conditions. In summary, our study provided valuable insights into the mechanisms of collagen degradation under different injury conditions, contributing to innovative strategies for designing collagen-related biomaterials in the future.

Zwitterionic doxorubicin loaded micelles based on polyethyleneimine for enhanced antitumor therapy in vivo

Zwitterionic groups of doxorubicin loaded micelles enhanced their antitumor performance in vivo.

Recent advances in regenerative biomaterials

Nowadays, biomaterials have evolved from the inert supports or functional substitutes to the bioactive materials able to trigger or promote the regenerative potential of tissues. The interdisciplinary progress has broadened the definition of 'biomaterials', and a typical new insight is the concept of tissue induction biomaterials. The term 'regenerative biomaterials' and thus the contents of this article are relevant to yet beyond tissue induction biomaterials. This review summarizes the recent progress of medical materials including metals, ceramics, hydrogels, other polymers and bio-derived materials. As the application aspects are concerned, this article introduces regenerative biomaterials for bone and cartilage regeneration, cardiovascular repair, 3D bioprinting, wound healing and medical cosmetology. Cell-biomaterial interactions are highlighted. Since the global pandemic of coronavirus disease 2019, the review particularly mentions biomaterials for public health emergency. In the last section, perspectives are suggested: (i) creation of new materials is the source of innovation; (ii) modification of existing materials is an effective strategy for performance improvement; (iii) biomaterial degradation and tissue regeneration are required to be harmonious with each other; (iv) host responses can significantly influence the clinical outcomes; (v) the long-term outcomes should be paid more attention to; (vi) the noninvasive approaches for monitoring in vivo dynamic evolution are required to be developed; (vii) public health emergencies call for more research and development of biomaterials; and (viii) clinical translation needs to be pushed forward in a full-chain way. In the future, more new insights are expected to be shed into the brilliant field-regenerative biomaterials.

Recent Advances in Biomedical Applications of Polymeric Nanoplatform Assisted with Two-Photon Absorption Process

Polymers are well-recognized carriers useful for delivering therapeutic drug and imaging probes to the target specified in the defined pathophysiological site. The functional drug molecules and imaging agents were chemically attached or physically loaded in the carrier polymer matrix via cleavable spacers. Using appropriate targeting moieties, these polymeric carriers (PCs) loaded with functional molecules were designed to realize target-specific delivery at the cellular level. The biodistribution of these carriers can be tracked using imaging agents with suitable imaging techniques. The drug molecules can be released by cleaving the spacers either by endogenous stimuli (e.g., pH, redox species, glucose level and enzymes) at the targeted physiological site or exogenous stimuli (e.g., light, electrical pulses, ultrasound and magnetism). Recently, two-photon absorption (2PA)-mediated drug delivery and imaging has gained significant attention because TPA from near-infrared light (700-950 nm, NIR) renders light energy similar to the one-photon absorption from ultraviolet (UV) light. NIR has been considered biologically safe unlike UV, which is harmful to soft tissues, cells and blood vessels. In addition to the heat and reactive oxygen species generating capability of 2PA molecules, 2PA-functionalized PCs were also found to be useful for treating diseases such as cancer by photothermal and photodynamic therapies. Herein, insights attained towards the design, synthesis and biomedical applications of 2PA-activated PCs are reviewed. In particular, specific focus is provided to the imaging and drug delivery applications with a special emphasis on multi-responsive platforms.

BOSHPY Fluorophores: BODIPY Analogues with Single Atom Controlled Aggregation

The reaction of diiminoisoindoline and iminoxoisoindoline with aminoazoles results in the formation of bidentate chelates that can be considered a semihemiporphyrazine. These chelates react with BF₃ to produce fluorescent compounds that are structurally analogous to the BODIPY dyes. These difluoroboron semihemiporphyrazines (BOSHPYs) aggregate, and the type of aggregation (H or J) is determined by a single atom at the periphery of the ligand (O or N). Notably, the imine terminated compounds remain fluorescent upon aggregation.

Self-Assembled Micelles of Amphiphilic PEGylated Drugs for Cancer Treatment

Generally, poor solubility and imprecise delivery of chemotherapeutic drugs can compromise their efficacies for clinical cancer treatment. In order to address such concerns, poor water-soluble drugs are conjugated with poly(ethylene glycol) (PEG) to obtain PEGylated drugs, which have improved water solubility and can also self-assemble in an aqueous solution to form micelles (PEGylated drug micelles). The surface PEG layer enhances the micelles' colloidal stability and reduces the interaction with physiological surroundings. Meanwhile, PEGylated drug micelles are tumor- targeting via the enhanced permeation and retention (EPR) effect to improve antitumor efficacy in comparison with free drugs. PEGylated drug micelles employ drugs as parts of the carrier medium, which increases the micelles' drug loading capacity relatively. The development of stimuli- responsive PEGylated drug micelles facilitates the drug release to be smart and controllable. Moreover, the PEGylated drug micelles show great potentials in overcoming the challenges of cancer therapy, such as multidrug resistance (MDR), angiogenesis, immunosuppression, and so on. In this review, we highlight the research progresses of PEGylated drug micelles, including the structures and properties, smart stimuli-responsive PEGylated drug micelles, and the challenges that have been overcome by PEGylated drug micelles.

Poly(lactic Acid): A Versatile Biobased Polymer for the Future with Multifunctional Properties-From Monomer Synthesis, Polymerization Techniques and Molecular Weight Increase to PLA Applications

Environmental problems, such as global warming and plastic pollution have forced researchers to investigate alternatives for conventional plastics. Poly(lactic acid) (PLA), one of the well-known eco-friendly biodegradables and biobased polyesters, has been studied extensively and is considered to be a promising substitute to petroleum-based polymers. This review gives an inclusive overview of the current research of lactic acid and lactide dimer techniques along with the production of PLA from its monomers. Melt polycondensation as well as ring opening polymerization techniques are discussed, and the effect of various catalysts and polymerization conditions is thoroughly presented. Reaction mechanisms are also reviewed. However, due to the competitive decomposition reactions, in the most cases low or medium molecular weight (MW) of PLA, not exceeding 20,000-50,000 g/mol, are prepared. For this reason, additional procedures such as solid state polycondensation (SSP) and chain extension (CE) reaching MW ranging from 80,000 up to 250,000 g/mol are extensively investigated here. Lastly, numerous practical applications of PLA in various fields of industry, technical challenges and limitations of PLA use as well as its future perspectives are also reported in this review.

Injectable and thermosensitive hydrogels mediating a universal macromolecular contrast agent with radiopacity for noninvasive imaging of deep tissues

It is very challenging to visualize implantable medical devices made of biodegradable polymers in deep tissues. Herein, we designed a novel macromolecular contrast agent with ultrahigh radiopacity (iodinate content > 50%) via polymerizing an iodinated trimethylene carbonate monomer into the two ends of poly(ethylene glycol) (PEG). A set of thermosensitive and biodegradable polyester-PEG-polyester triblock copolymers with varied polyester compositions synthesized by us, which were soluble in water at room temperature and could spontaneously form hydrogels at body temperature, were selected as the demonstration materials. The addition of macromolecular contrast agent did not obviously compromise the injectability and thermogelation properties of polymeric hydrogels, but conferred them with excellent X-ray opacity, enabling visualization of the hydrogels at clinically relevant depths through X-ray fluoroscopy or Micro-CT. In a mouse model, the 3D morphology of the radiopaque hydrogels after injection into different target sites was visible using Micro-CT imaging, and their injection volume could be accurately obtained. Furthermore, the subcutaneous degradation process of a radiopaque hydrogel could be non-invasively monitored in a real-time and quantitative manner. In particular, the corrected degradation curve based on Micro-CT imaging well matched with the degradation profile of virgin polymer hydrogel determined by the gravimetric method. These findings indicate that the macromolecular contrast agent has good universality for the construction of various radiopaque polymer hydrogels, and can nondestructively trace and quantify their degradation in vivo. Meanwhile, the present methodology developed by us affords a platform technology for deep tissue imaging of polymeric materials.

ROS Responsive Nanoplatform with Two-Photon AIE Imaging for Atherosclerosis Diagnosis and "Two-Pronged" Therapy

Atherosclerosis, characterized by endothelial injury, progressive inflammation, and lipid deposition, can cause cardiovascular diseases. Although conventional anti-inflammatory drugs reveal a certain amount of therapeutic effect, more reasonable design on plaque targeting, local anti-inflammation, and lipid removal are still required for comprehensive atherosclerosis therapy. In this work, a theranostic nanoplatform is developed for atherosclerosis recognition and inhibition. A two-photon aggregation-induced emission (AIE) active fluorophore (TP) developed is linked to β-cyclodextrin (CD) with a ROS responsive bond, which can carry prednisolone (Pred) in its entocoele via supramolecular interaction to build a diagnosis-therapy compound two-photon fluorophore-cyclodextrin/prednisolone complexes (TPCDP). With TPCDP packaged by nanosized micelles based on a ROS sensitive copolymer poly (2-methylthio ethanol methacrylate)-poly (2-methacryloyloxyethyl phosphorylcholine), the TPCDP@PMM can accumulate in atherosclerotic tissue through the damaged vascular endothelium. Activated by the local overexpressed ROS and rich lipid, the micelles are interrupted and TPCDP is further disintegrated with Pred release due to the relatively stronger interaction of lipid with CD, resulting in anti-inflammatory activity and lipid removal for atherosclerosis inhibition. Besides, labeled with the TP, TPCDP@PMM indicates a distinct two-photon AIE imaging on atherosclerosis recognition. The "two-pronged" therapeutic effect and plaque location ability has been confirmed in vivo on ApoE^-/- mice, holding TPCDP@PMM a great promise for atherosclerosis theranostics.