Amylase-Protected Ag Nanodots for in vivo Fluorescence Imaging and Photodynamic Therapy of Tumors

Recent Advances of Tumor Microenvironment-Responsive Nanomedicines-Energized Combined Phototherapy of Cancers

Photodynamic therapy (PDT) has emerged as a powerful tumor treatment tool due to its advantages including minimal invasiveness, high selectivity and thus dampened side effects. On the other side, the efficacy of PDT is severely frustrated by the limited oxygen level in tumors, thus promoting its combination with other therapies, particularly photothermal therapy (PTT) for bolstered tumor treatment outcomes. Meanwhile, nanomedicines that could respond to various stimuli in the tumor microenvironment (TME) provide tremendous benefits for combined phototherapy with efficient hypoxia relief, tailorable drug release and activation, improved cellular uptake and intratumoral penetration of nanocarriers, etc. In this review, we will introduce the merits of combining PTT with PDT, summarize the recent important progress of combined phototherapies and their combinations with the dominant tumor treatment regimen, chemotherapy based on smart nanomedicines sensitive to various TME stimuli with a focus on their sophisticated designs, and discuss the challenges and future developments of nanomedicine-mediated combined phototherapies.

Oxidative Stimuli-Responsive "Pollen-Like" Exosomes from Silver Nanoflowers Remodeling Diabetic Wound Microenvironment for Accelerating Wound Healing

The hostile oxidative wound microenvironment, defective angiogenesis, and uncontrolled release of therapeutic factors are major challenges in improving the diabetic wound healing. Herein, adipose-derived-stem-cell-derived exosomes (Exos) are first loaded into Ag@bovine serum albumin (BSA) nanoflowers (Exos-Ag@BSA NFs) to form a protective "pollen-flower" delivery structure, which are further encapsulated into the injectable collagen (Col) hydrogel (Exos-Ag@BSA NFs/Col) for concurrent remodeling of the oxidative wound microenvironment and precise release of Exos. The Exos-Ag@BSA NFs can selectively dissociate in an oxidative wound microenvironment, which triggers sustained release of Ag ions (Ag+ ) and cascades controllable release of "pollen-like" Exos at the target site, thus protecting Exos from oxidative denaturation. Such a wound-microenvironment-activated release property of Ag+ and Exos effectively eliminates bacteria and promotes the apoptosis of impaired oxidative cells, resulting in improved regenerative microenvironment. Additionally, Exos-Ag@BSA NFs/Col markedly accelerates wound healing and regeneration in vivo in a diabetic murine silicone-splinted excisional wound model by promoting blood perfusion, tissue granulation, collagen deposition, neovascularization, angiogenesis, and re-epithelization. It is anticipated that this work will inspire the development of more delicate and disease-specific therapeutic systems for clinical wound management.

Conjugated Polymeric Materials in Biological Imaging and Cancer Therapy

Conjugated polymers (CPs) have attracted much attention in the fields of chemistry, medicine, life science, and material science. Researchers have carried out a series of innovative researches and have made significant research progress regarding the unique photochemical and photophysical properties of CPs, expanding the application range of polymers. CPs are polymers formed by the conjugation of multiple repeating light-emitting units. Through precise control of their structure, functional molecules with different properties can be obtained. Fluorescence probes with different absorption and emission wavelengths can be obtained by changing the main chain structure. By modifying the side chain structure with water-soluble groups or selective recognition molecules, electrostatic interaction or specific binding with specific targets can be achieved; subsequently, the purpose of selective recognition can be achieved. This article reviews the research work of CPs in cell imaging, tumor diagnosis, and treatment in recent years, summarizes the latest progress in the application of CPs in imaging, tumor diagnosis, and treatment, and discusses the future development direction of CPs in cell imaging, tumor diagnosis, and treatment.

Biofilm Homeostasis Interference Therapy via 1 O2 -Sensitized Hyperthermia and Immune Microenvironment Re-Rousing for Biofilm-Associated Infections Elimination

The recurrence of biofilm-associated infections (BAIs) remains high after implant-associated surgery. Biofilms on the implant surface reportedly shelter bacteria from antibiotics and evade innate immune defenses. Moreover, little is currently known about eliminating residual bacteria that can induce biofilm reinfection. Herein, novel "interference-regulation strategy" based on bovine serum albumin-iridium oxide nanoparticles (BIONPs) as biofilm homeostasis interrupter and immunomodulator via singlet oxygen (¹ O₂ )-sensitized mild hyperthermia for combating BAIs is reported. The catalase-like BIONPs convert abundant H₂ O₂ inside the biofilm-microenvironment (BME) to sufficient oxygen gas (O₂ ), which can efficiently enhance the generation of ¹ O₂ under near-infrared irradiation. The ¹ O₂ -induced biofilm homeostasis disturbance (e.g., sigB, groEL, agr-A, icaD, eDNA) can disrupt the sophisticated defense system of biofilm, further enhancing the sensitivity of biofilms to mild hyperthermia. Moreover, the mild hyperthermia-induced bacterial membrane disintegration results in protein leakage and ¹ O₂ penetration to kill bacteria inside the biofilm. Subsequently, BIONPs-induced immunosuppressive microenvironment re-rousing successfully re-polarizes macrophages to pro-inflammatory M1 phenotype in vivo to devour residual biofilm and prevent biofilm reconstruction. Collectively, this ¹ O₂ -sensitized mild hyperthermia can yield great refractory BAIs treatment via biofilm homeostasis interference, mild-hyperthermia, and immunotherapy, providing a novel and effective anti-biofilm strategy.

Carrier-Free Delivery of Ultrasmall π-Conjugated Oligomer Nanoparticles with Photothermal Conversion over 80% for Cancer Theranostics

High-performance photothermal theranostics is urgently desired for cancer therapy because of their good controllability and noninvasive features. The relatively low photothermal conversion efficiency is still at the drawbacks because of the absence of efficient extraneous carriers. Herein, a carrier-free nanomedicine is developed to in vivo self-deliver organic photothermal agents for efficient cancer phototheranostics. By a facile self-assembly strategy, the near-infrared (NIR)-absorbing conjugated oligomer IDIC-4F is fabricated into a carrier-free nanoparticle (DCF-P), showing ultrasmall size of nearly 4.0 nm with a nearly 100% of drug loading capacity. Notably, DCF-P achieves a superhigh photothermal conversion efficiency of 80.5% that is far greater than that of IDIC-4F-loaded nanomicelle DCF-M (57.3%). With the guidance of NIR fluorescence and photoacoustic dual-imaging, it is verified that DCF-P could well achieve tumor-preferential accumulation and retention at 4 h postinjection, and meanwhile shows highly efficient in vivo tumor elimination with good biosafety. This study thus contributes a novel concept for designing ultrasmall nanoparticle characteristics of preferential accumulation in tumors, and also provides a strategy for creating high-performance carrier-free nanomedicine via highly ordered molecular stacking.

Recent Advances in Hypoxia-Overcoming Strategy of Aggregation-Induced Emission Photosensitizers for Efficient Photodynamic Therapy

Hypoxia is an inherent physiologic barrier in the microenvironment of solid tumor and has badly restricted the therapeutic effect of photodynamic therapy (PDT). Meanwhile, the photosensitizer (PS) agents used for PDT applications regularly encounter the tiresome aggregation-caused quenching effect that seriously decreases the production efficiency of cytotoxic reactive oxygen species. The aggregation-induced emission (AIE) PSs with antiquenching characteristics in the aggregate state are considered as a promising tool for achieving highly efficient PDT applications, and plenty of studies have widely demonstrated their advantages in various diseases. Herein, the recent progress of AIE PSs in the battle of antitumor hypoxia issue is summarized and the practical molecular principles of hypoxia-overcoming AIE PSs are highlighted. According to the hypoxia-overcoming mechanism, these representative cases are divided into low O₂ -dependent (type I PDT) and O₂ -dependent tactics (mainly including O₂ -enrichment type II PDT and combination therapy). Furthermore, the underlying challenges and prospects of AIE PSs in hypoxia-overcoming PDT are proposed and thus expect to promote the next development of AIE PSs.

In situ immobilization of silver nanocrystals in carbon nanoparticles for intracellular fluorescence imaging and hydroxyl radicals detection

Silver nanoparticles (Ag NPs) have attracted extensive research interest in bioimaging and biosensing due to their unique surface plasmon resonance. However, the potential aggregation and security anxiety of Ag NPs hinder their further application in biomedical field due to their high surface energy and the possible ionization. Here, binary heterogeneous nanocomplexes constructed from silver nanoparticles and carbon nanomaterials (termed as C-Ag NPs) were reported. The C-Ag NPs with multiple yolk structure were synthesized via a one-step solvothermal route using toluene as carbon precursor and dispersant. The hydrophilic functional groups on the carbon layer endowed the C-Ag NPs excellent chemical stability and water-dispersity. Results showed that C-Ag NPs demonstrated excellent safety profile and excellent biocompatibility, which could be used as an intracellular imaging agent. Moreover, the C-Ag NPs responded specifically to hydroxyl radicals and were expected to serve as a flexible sensor to efficiently detect diseases related to the expression of hydroxyl radicals in the future.

Conjugated Polymers: Optical Toolbox for Bioimaging and Cancer Therapy

Conjugated polymers (CPs) are capable of coordinating the electron coupling phenomenon to bestow powerful optoelectronic features. The light-harvesting and light-amplifying properties of CPs are extensively used in figuring out the biomedical issues with special emphasis on accurate diagnosis, effective treatment, and precise theranostics. This review summarizes the recent progress of CP materials in bioimaging, cancer therapeutics, and introduces the design strategies by rationally tuning the optical properties. The recent advances of CPs in bioimaging applications are first summarized and the challenges to clear the future directions of CPs in the respective area are discussed. In the following sections, the focus is on the burgeoning applications of CPs in phototherapy of the tumor, and illustrates the underlying photo-transforming mechanism for further molecular designing. Besides, the recent progress in the CPs-assistant drug therapy, mainly including drug delivery, gene therapeutic, the optical-activated reversion of tumor resistance, and synergistic therapy has also been discussed elaborately. In the end, the potential challenges and future developments of CPs on cancer diagnosis and therapy are also illuminated for the improvement of optical functionalization and the promotion of clinical translation.

Multiconformational analysis of tripeptides upon consideration of implicit and explicit hydration effects

During the last two decades, numerous observed data obtained by various physical techniques, also supported by molecular modeling approaches, have highlighted the structuring features of tripeptides, as well as their aggregation properties. Herein, we focus on the structural dynamics of four trimers, i.e., Gly-Gly-Gly, Gly-Ala-Gly, Ala-Ala-Ala and Ala-Phe-Ala, in an aqueous environment. Density functional theory calculations (DFT) were carried out to assess the stability of four types of secondary structures, i.e., β-strand, polyproline-II (pP-II), α-helix and γ-turn, of which the formation had been described in these tripeptides. Both implicit and explicit hydration effects were analyzed on the conformational and energetic features of trimers. It has been shown that the use of M062X functional (versus B3LYP) improve the stability of intramolecular H-bonds, especially in inverse γ-turn structures, as well as the energetic and conformational equilibrium in all tripeptides. Explicit hydration reflected by the presence of five water molecules around the backbone polar sites (NH₃⁺, N-H, CO and NH₂) considerably changes the conformational landscapes of the trimers. Characteristic intramolecular and intermolecular interactions evidenced by the calculations, were emphasized.