Tuning the Brightness and Photostability of Organic Dots for Multivalent Targeted Cancer Imaging and Surgery

Design of donor-acceptor conjugated polymers based on diketopyrrolopyrrole for NIR-II multifunctional imaging

Diketopyrrolopyrrole (DPP) is an excellent photosensitizer and photothermal agent with the advantages of good planarity, strong electron affinity, high electron mobility, easy purification, easy structural modification and high molar absorption coefficient. It is regarded as one of the ideal choices for the design and synthesis of efficient organic photovoltaic materials. Therefore, two kinds of donor-acceptor (D-A) conjugated polymers were designed and synthesized with DPP as the acceptor, and their optical properties and applications in the near-infrared region were studied. The quantum yield (QY) of PBDT-DPP is 0.46%, and the highest temperature reached within 10 minutes after irradiation with a 660 nm laser is 60 °C. Another polymer, EDOT-DPP, has a QY of 0.48%, and its semiconductor polymer nanoparticle aqueous solution can reach 60 °C within 12 minutes under laser irradiation, achieving photothermal treatment of nude mice tumors. Both polymer NPs have good biocompatibility and promising applications in bioimaging and photothermal therapy.

NIR-II organic small molecule probe for labeling lymph nodes and guiding tumor imaging

Organic small molecule fluorescent groups have injected new material support into the field of medical imaging due to their unique luminescence mechanism and easy tuning of structure. The great potential of NIR-II window imaging forces us to continuously optimize the structure of organic fluorophores to design better fluorescent molecules for fluorescence imaging-guided surgery. An ideal organic small molecule fluorescent group: it can penetrate into the inside of the organism, clearly present the internal structure and the edge contour of different tissues, so as to perfectly achieve internal imaging and accurately guide external surgery. In vivo, fluorescent groups do not damage normal tissues and organs. However, problems such as low quantum yield and poor biocompatibility greatly limit the clinical transformation of NIR-II fluorescent small molecules. To avoid the shortcomings of NIR-II fluorescent probes as much as possible and better realize image-guided surgery, in this experiment, the biplane donor unit was incorporated into the twisted D-π-A-π-D structure to expand the conjugated structure of the fluorescent group, which not only realized NIR-II emission, but also had high quantum yield and biosafety.

A nanoparticle composed of totally hospital-available drugs and isotope for fluorescence/SPECT dual-modal imaging-guided photothermal therapy to inhibit tumor metastasis

As primary sites of tumor metastasis, sentinel lymph nodes (SLNs) require a highly biocompatible theranostic platform for precise localization and treatment to inhibit tumor metastasis. Herein, indocyanine green-human serum albumin (ICG-HSA) nanoparticles (NPs) were fabricated by ICG-induced self-assembly and radiolabeled with technetuim-99 m (99mTc). The fabricated NPs were composed of hospital-available drugs and isotopes, making them highly biocompatible for in vivo applications. In a mouse model of SLN metastasis, the prepared NPs exhibited excellent capacity for preoperative planning by single-photon emission computed tomography (SPECT) imaging-enabled SLN localization, near-infrared fluorescence (NIRF) imaging-enabled intraoperative real-time monitoring, and SLN photothermal treatment. Photothermal treatment with SLN enhanced the inhibition of lung metastasis and significantly increased the survival time of mice. The prepared NPs were highly biocompatible and exhibited efficient theranostic properties for inhibiting cancer metastasis, making them promising candidates for clinical translation.

Single-Molecule Dendritic MRI Nanoprobes Reveal the Size-Dependent Tumor Entrance

The tumor entrance of drug delivery systems, including therapeutic proteins and nanomedicine, plays an essential role in affecting the treatment outcome. Nanoparticle size is a critical but contradictory factor in making a trade-off among blood circulation, tumor accumulation, and penetration. Here, this work designs a series of single-molecule gadolinium (Gd)-based magnetic resonance imaging (MRI) nanoprobes with well-defined sizes to precisely explore the size-dependent tumor entrance in vivo. The MRI nanoprobes obtained by divergent synthesis contain a core molecule of macrocyclic Gd(III)-chelate and different layers of dendritic lysine units, mimicking globular protein. This work finds that the r1 relaxivity and MR imaging signals increase with the nanoparticle size. The nanoprobe with a lower limit of critical size threshold ≈8.0 nm achieves superior tumor accumulation and penetration. These single-molecule MRI nanoprobes can be served to precisely examine the size-related nanoparticle-biological interactions.

Research Status of Dendrimer Micelles in Tumor Therapy for Drug Delivery

Dendrimers are a family of polymers with highly branched structure, well-defined composition, and extensive functional groups, which have attracted great attention in biomedical applications. Micelles formed by dendrimers are ideal nanocarriers for delivering anticancer agents due to the explicit study of their characteristics of particle size, charge, and biological properties such as toxicity, blood circulation time, biodistribution, and cellular internalization. Here, the classification, preparation, and structure of dendrimer micelles are reviewed, and the specific functional groups modified on the surface of dendrimers for tumor active targeting, stimuli-responsive drug release, reduced toxicity, and prolonged blood circulation time are discussed. In addition, their applications are summarized as various platforms for biomedical applications related to cancer therapy including drug delivery, gene transfection, nano-contrast for imaging, and combined therapy. Other applications such as tissue engineering and biosensor are also involved. Finally, the possible challenges and perspectives of dendrimer micelles for their further applications are discussed.

Overcome the "Buckets Effect": Integration of AIEgens into Proteins for Fluorescence-Enhanced Two-Photon Imaging

Luminogens with aggregation-induced emission characteristics (AIEgens) are considered good options for two-photon (2P) probes, owing to their flexibility of design, heavy-metal-free composition, and resistance to photobleaching. However, the design principles for large 2P absorption cross-section (δ) generally require high coplanarity, strong donor-acceptor (D-A) interactions, and long conjugation, which can severely weaken the brightness of AIEgens at the aggregated state and undermine their potential in 2P fluorescence imaging (2PFI). Exploration of a feasible approach to overcome the "Buckets Effect" of AIEgen-based 2P probes is thus a fascinating yet challenging task. Herein, an AIEgen, namely (Z)-2-(4-aminophenyl)-3-(5-(4-(bis(4-methoxyphenyl)amino)phenyl)thiophen-2-yl)acrylonitrile (MTAA) is designed to have a big δ according to the calculation result and a low fluorescence quantum yield (QY) of 2.2% in dimethyl sulfoxide (DMSO). Impressively, upon integrating into bovine serum albumin (BSA), the protein-sized MTAA@BSA dots exhibit a 25-fold higher fluorescence QY compared to MTAA molecules, contributing to an imaging depth of 818 µm in the brain vasculature. The retention and clearance of MTAA@BSA dots in the liver and kidney are also studied using 2PFI. Overall, this work provides a facile approach to overcome the "Buckets Effect" of AIEgen to generate highly efficient, reliable, and biocompatible 2P probes.

Surface chemistry mediates the tumor entrance of nanoparticles probed using single-molecule dual-imaging nanodots

The active transport of nanoparticles into solid tumors through transcytosis has been recognized as a promising way to enhance tumor accumulation and penetration, but the effect of the physicochemical properties of nanoparticles remains unclear. Herein, we develop a type of single-molecule dual imaging nanodot by divergent growth of perylenediimide (PDI)-dye-cored polylysine dendrimers and internal orthogonal conjugation of Gd(III)-based macrocyclic probes for fluorescence imaging and magnetic resonance imaging (MRI) of surface chemistry-dependent tumor entrance. The MRI and fluorescence imaging show that sixth-generation nanodots with acetylated (G6-Ac) and oligo ethylene glycol (G6-OEG) surfaces exhibit similar high tumor accumulation but different intratumor distribution. Cellular uptake and transport experiments suggest that G6-Ac nanodots have lower lysosomal entrapment (61% vs. 83%) and a higher exocytotic rate (47% vs. 29%) than G6-OEG. Therefore, G6-Ac is more likely to undergo intercellular transport through cell transcytosis, and is able to reach a tumor area distant from blood vessels, while G6-OEG mainly enters the tumor through enhanced permeability and retention (EPR) effect-based passive transport, and is not able to deliver to distant tumor areas. This study suggests that it is possible to boost the tumor entrance of nanoparticles by engineering surface chemistry for active transport.

Preparation and Application of High-Efficiency, Antibacterial, and Antiviral PET-PTHP Fibers

Transmission through the respiratory tract is one of the most important ways for bacteria and viruses to infect the human body; the use of high-performance antibacterial and antiviral protective equipment is the most effective way to prevent the spread of respiratory diseases. However, at present, most personal protective equipment lacks the ability to kill pathogens. In this paper, a kind of polytetrahydropyrimidine-polyethylene terephthalate functional fiber (PET-PTHP fibers) with highly sustained antibacterial and antiviral properties was prepared. The inactivation rate of the fibers against Staphylococcus aureus and Escherichia coli was as high as 99.99%, and the antibacterial time was more than 72 h. The fibers have an obvious destructive effect on lentiviruses and can reduce the infection rate of lentiviruses in BxPC-3 cells from 25.4 to 9.7%. The cytotoxicity test, cell live/dead staining test, and cell proliferation test all confirmed that PET-PTHP fibers have no obvious cytotoxicity and good cytocompatibility. By applying the functional fibers to the inner layer of the masks, a new type of mask with adsorption, filtration, and killing properties against pathogens was prepared. The filtration efficiency of the new masks was 99.3%, and the pressure drop was 104 Pa. The new masks have excellent air permeability and filtration effect, meet the practical application conditions, and are of grade A; therefore, these masks provide medical protection as well as kill pathogens at the same time, further reducing the risk of human infection.

Donor-Acceptor-Donor small molecules for fluorescence/photoacoustic imaging and integrated photothermal therapy

Here, a D-A-D type fluorescent conjugated molecule with a high molar absorption coefficient and emission at 1120 nm in the near-infrared region was synthesized. Conjugated molecules and two polyethylene glycol polymers with different lipophilic ends are assembled into water-soluble nanoparticles to improve their biocompatibility. Then, their physical and chemical properties were studied and compared. Compared with phospholipid-based PEG, styrene-based PEG can reduce the π-π stacking between molecules and the quenching caused by molecular aggregation. It has more advantages in particle size and fluorescence performance and can be better used in biological imaging. In addition, the Nano-particles have good photo-thermal conversion efficiency; the temperature rises to 62.8°C after 980 nm irradiation for 6 min, which can be used as a potential near-infrared II photothermal therapeutic agent. In vivo imaging experiments confirmed that nanomaterials have fluorescence, photoacoustic dual-modal imaging and good biological safety. STATEMENT OF SIGNIFICANCE: : In this work, we constructed D-A-D type dual donor fluorescent molecules using BBTD, CPDT and EDOT, and used amphiphilic polymers to improve their biocompatibility. Compared with DSPE NPs, PS-NPs can reduce intermolecular π-π stacking and increase quantum yield (QY = 0.98 %). Deep penetration and low biological toxicity make it have biomedical value and realize the integration of multi-functional collaborative imaging. This work can still be further improved and supplemented, and the molecular structure can be optimized to improve its application in biomedical imaging.

Screening of a short chain antimicrobial peptide-LKLHI and its application in hydrogels for wound healing

Antibacterial peptides have been widely used in the field of antibacterial due to their biocompatibility. In this work, owing to quickly screen out peptides with antibacterial effects, the bacterial membranes of E. coli and S. aureus were extracted and fixed on self-made silica gel microspheres to prepare bacterial membrane chromatography stationary phase. We successfully screened antimicrobial peptides from a peptide library composed of one-bead-one-compound by bacterial membrane chromatography. The antibacterial peptide has an effective defense effect on gram-positive bacteria, gram-negative bacteria, and fungi. In addition, the antibacterial peptide has almost no hemolysis and cytotoxicity and other excellent biocompatibility and has excellent properties such as stability, broad-spectrum antibacterial, and promotion of wound healing，and HA hydrogel carrier loaded with antimicrobial peptides was prepared, which provided the application direction of antimicrobial dressings for antimicrobial peptides. In summary, this method can screen out polypeptides with antibacterial effects, and the screened-out antibacterial peptides are expected to be applied in clinical applications.

Dye-cored polylysine dendrimer as luminescent nanoplatform for imaging-guided anticancer drug delivery

Dendrimers have numerous applications in imaging and drug delivery. Designing a dendrimer diagnostic platform with a well-defined structure and controlled drug delivery is a formidable challenge. Here, we design dendritic polymer-platinum conjugates (G5-PEG-Pt) as pH-responsive nanovesicles for imaging-guided platinum drug delivery. The G5-PEG-Pt have a well-defined structure, intrinsically bright fluorescence, and acid-responsive drug release. The pH-responsive G5-PEG-Pt could rapidly release the platinum drug at acidic pH (5.0) than neutral pH (7.4). The G5-PEG-Pt could enter SKOV-3 human ovarian cancer cells by the endocytosis pathway and exhibited comparative cytotoxicity to free cisplatin. By virtue of the prolonged blood circulation time and the enhanced permeability and retention (EPR) effect, a 4.4-fold higher tumor platinum uptake than that of free cisplatin was achieved, potentially enhancing the therapeutic indexes of the platinum drug. Therefore, these pH-responsive platinum and fluorescent dendrimer conjugates are expected to be potent in vivo cancer optical imaging and therapy platforms.

Elastic Fluorescent Protein-Based Down-Converting Optical Films for Flexible Display

Protein-based material design provides great advantages to developing smart biomaterials with tunable structures and desired functions. They have been widely used in many biomedical applications including tissue engineering and drug delivery. However, protein-based materials are not yet widely used in optoelectronic materials despite their excellent optical and tunable mechanical properties. Here, we synthesized engineered fluorescent proteins (FPs) fused with elastic protein for the development of optoelectrical down-converting optical filters for flexible display materials. We synthesized sequence-specific FPs to tune blue, green, yellow, and red colors and fused them with elastic protein to tune mechanical properties. We fabricated flexible self-supporting film materials and characterized mechanical properties and down-converting optical properties. We also fabricated a hybrid light-emitting diode (LED) to down convert blue to desired green, red, and white colors. Furthermore, we constructed a flexible white LED using organic LED as a flexible substrate. Our modular synthesis approach of tunable bio-optoelectrical material approaches will be useful to design future biocompatible and flexible display materials and technologies.

Large-area fluorescence enhancement of R6G based on a uniform PVA-Au plasmonic substrate

With the development of surface enhanced fluorescence (SEF) spectroscopy technology, uniform and low-cost SEF substrate is urgently needed. In this paper, the nanocomposite films of poly (vinyl alcohol) (PVA) embedded with in-situ Au particles, their localized surface plasmon resonance (LSPR) bands locate at different wavelengths from 525 nm to 569 nm, were used as substrates to enhance the fluorescence of rhodamine 6 G (R6G). The results shows that the uniform light emission in large area can be measured, and the maximum enhancement factor (EF) is about 13 folds. With increasing concentration of R6G films, the EF first increases and then slowly decreases. It is demonstrated that the EF greatly depends on the matching degree of the emission/excitation of R6G and the LSPR band of PVA-Au substrate. All the results further suggests that the PVA-Au substrate not only realize the fluorescence enhancement but also attenuates the fluorescence quenching at higher concentration. In addition, the local electric distribution of the substrate is simulated by using three-dimensional finite different time-domain (FDTD) to further demonstrate the mechanism of the SEF. This substrate has good development prospects in the fields of fluorescent probes and fluorescence imaging, which can be beneficial to the development of uniform and low-cost SEF substrate.

Near-Infrared Emitting Poly(amidoamine) Dendrimers with an Anthraquinone Core toward Versatile Non-Invasive Biological Imaging

Today, there is a very strong demand for versatile near-infrared (NIR) imaging agents suitable for non-invasive optical imaging in living organisms (in vivo imaging). Here, we created a family of NIR-emitting macromolecules that take advantage of the unique structure of dendrimers. In contrast to existing fluorescent dendrimers bearing fluorophores at their periphery or in their cavities, a NIR fluorescent structure is incorporated into the core of the dendrimer. Using the poly(amidoamine) dendrimer structure, we want to promote the biocompatibility of the NIR-emissive system and to have functional groups available at the periphery to obtain specific biological functionalities such as the ability to deliver drugs or for targeting a biological location. We report here the divergent synthesis and characterization by NMR and mass spectrometries of poly(amidoamine) dendrimers derived from the fluorescent NIR-emitting anthraquinone core (AQ-PAMAF). AQ-PAMAFs ranging from the generation -0.5 up to 3 were synthesized with a good level of control resulting in homogeneous and complete dendrimers. Absorption, excitation, and emission spectra, as well as quantum yields, of AQ-PAMAFs have been determined in aqueous solutions and compared with the corresponding properties of the AQ-core. It has been demonstrated that the absorption bands of AQ-PAMAFs range from UV to 750 nm while emission is observed in the range of 650-950 nm. Fluorescence macroscopy experiments confirmed that the NIR signal of AQ-PAMAFs can be detected with a satisfactory signal-to-noise ratio in aqueous solution, in blood, and through 1 mm thick tissue-mimicking phantom. The results show that our approach is highly promising for the design of an unprecedented generation of versatile NIR-emitting agents.

An Orthogonal Protection Strategy for Synthesizing Scaffold-Modifiable Dendrons and Their Application in Drug Delivery

Dendrons have well-defined dendritic structures. However, it is a great challenge to preserve their high structural definition after multiple functionalization because the site-selective conjugation of different functional molecules is quite difficult. Scaffold-modifiable dendrons that have orthogonal reactive groups at the scaffold and periphery are ideal for achieving the site-specific bifunctionalization. In this paper, we present a new strategy for synthesizing scaffold-modifiable dendrons via orthogonal amino protection and a solid-phase synthesis method. This strategy renders the reactive sites at the scaffold and periphery of the dendrons a super selectivity, high reactivity, and wide applicability to various reaction types. The fourth-generation dendrons can be facilely synthesized within 2 days without structural defects as demonstrated by mass spectrometry. We conjugated doxorubicin (DOX) and phenylboronic acid (PBA) groups to the scaffold and periphery, respectively. Thanks to the PBA-enhanced lysosome escape, tumor targeting ability, and tumor permeability as well as the high drug loading content larger than 30%, the dendron-based prodrug exhibited extraordinary antitumor efficacy and could eradicate the tumors established in mice by multiple intravenous administration. This work provides a practical strategy for synthesizing scaffold-modifiable dendrons that can be a promising nanoplatform to achieve function integration in a precisely controlled manner.

Synthesis of polyacrylonitrile/polytetrahydropyrimidine (PAN/PTHP) nanofibers with enhanced antibacterial and anti-viral activities for personal protective equipment

Emerging infectious diseases caused by the spread of bacteria and viruses are a major burden on global economic development and public health. At present, most personal protective equipment has weak antibacterial and anti-viral properties. The PAN/PTHP nanofibers reported in this article provide a new method for the development of personal protective equipment. In this study, a mixture of PTHP and PAN was prepared into PAN/PTHP nanofibers with high-efficiency and long-lasting antibacterial effects (>99.999%) through the electrospinning process. Live/dead staining and cell proliferation experiments showed that the preparation of PAN/PTHP nanofibers has good cell compatibility. In addition, PAN/PTHP nanofibers show obvious destructive effects on lentiviruses. Based on these characteristics, PAN/PTHP nanofibers were applied to facial masks, which can be used as the inflatable biocidal layer of facial masks and have an excellent interception effect on particles in the air. The successful synthesis of these fascinating materials may provide new insights for the development of new protective materials.

Recent Developments in the Study of the Microenvironment of Cancer and Drug Delivery

Cancer is characterized by disrupted molecular variables caused by cells that deviate from regular signal transduction. The uncontrolled segment of such cancerous cells annihilates most of the tissues that contact them. Gene therapy, immunotherapy, and nanotechnology advancements have resulted in novel strategies for anticancer drug delivery. Furthermore, diverse dispersion of nanoparticles in normal stroma cells adversely affects the healthy cells and disrupts the crosstalk of tumour stroma. It can contribute to cancer cell progression inhibition and, conversely, to acquired resistance, enabling cancer cell metastasis and proliferation. The tumour's microenvironment is critical in controlling the dispersion and physiological activities of nano-chemotherapeutics which is one of the targeted drug therapy. As it is one of the methods of treating cancer that involves the use of medications or other substances to specifically target and kill off certain subsets of malignant cells. A targeted therapy may be administered alone or in addition to more conventional methods of care like surgery, chemotherapy, or radiation treatment. The tumour microenvironment, stromatogenesis, barriers and advancement in the drug delivery system across tumour tissue are summarised in this review.

Molecular level precision and high molecular weight peptide dendrimers for drug-specific delivery

Peptide dendrimers have a broad application in biomedical science due to their biocompatibility, diversity, and multifunctionality, but the precision synthesis of high-molecule weight peptide dendrimers remains challenging. We here report the facile and liquid-phase synthesis of molecular level precision and amino-acid built-in polylysine (PLL) dendrimers with molecular weights as high as ∼60 kDa. Three types of polyhedral oligosilsesquioxane (POSS)-cored PLL dendrimers with phenylalanine, tyrosine, or histidine as building blocks were synthesized. The precise structures of the dendrimers were confirmed by MALDI-TOF MS, GPC, and ¹H NMR spectroscopy. The interior functionalized peptide dendrimers improved the encapsulation capability of SN38 and sustained the release profiles. Enhanced molecular interactions between the peptide dendrimers and drugs were explored by both NMR experiments and computer simulations. The peptide dendrimer/SN38 formulations showed potent antitumor activity against multiple cancer cell lines. We believe that this strategy can be applied to the synthesis of tailor-made functional peptide dendrimers for drug-specific delivery and other diverse biomedical applications.

Linear-Dendritic Polymer-Platinum Complexes Forming Well-Defined Nanocapsules for Acid-Responsive Drug Delivery

Polymeric nanocapsules hold considerable applications in cancer drug delivery, but the synthesis of well-defined nanocapsules with a tunable drug release property remains a significant challenge in fabrication. Herein, we demonstrate a supramolecular complexation strategy to assemble small molecular platinum (Pt) compounds into well-defined nanocapsules with high drug loading, acidity-sensitivity, and tunable Pt releasing profile. The design utilizes poly(ethylene glycol)-dendritic polylysine-G4/amides to complex with Pt compounds, forming stable nanocapsules with diameters approximately ∼20 nm and membrane thickness around several nanometers. The stability, drug content, and release profiles are tunable by tailoring the dendritic structure. The designated polymer-Pt nanocapsules, PEG-G4/MSA-Pt, showed sustained blood retention, preferential tumor accumulation, enhanced cellular uptake, lysosomal drug release, and nuclear delivery capability. PEG-G4/MSA-Pt showed enhanced antitumor efficacy compared to free cisplatin and other nanocapsules, which stopped the progression of both A549 cell xenografts and patient-derived xenografts (PDXs) of hepatocellular carcinoma on a mice tumor model. Thus, we believe this strategy is promising for developing Pt-based nanomedicine for cancer drug delivery.

Recent advances in drug delivery systems for enhancing drug penetration into tumors

The emergence of nanomaterials for drug delivery provides the opportunity to avoid the side effects of systemic drug administration and injury caused by the removal of tumors, delivering great promise for future cancer treatments. However, the efficacy of current nano drugs is not significantly better than that of the original drug treatments. The important reason is that nano drugs enter the tumor vasculature, remaining close to the blood vessels and unable to enter the tumor tissue or tumor cells to complete the drug delivery process. The low efficiency of drug penetration into tumors has become a bottleneck restricting the development of nano-drugs. Herein, we present a systematic overview of recent advances on the design of nano-drug carriers in drug delivery systems for enhancing drug penetration into tumors. The review is organized into four sections: The drug penetration process in tumor tissue includes paracellular and transcellular transport, which is summarized first. Strategies that promote tumor penetration are then introduced, including methods of remodeling the tumor microenvironment, charge inversion, dimensional change, and surface modification of ligands which promote tissue penetration. Conclusion and the prospects for the future development of drug penetration are finally briefly illustrated. The review is intended to provide thoughts for effective treatment of cancer by summarizing strategies for promoting the endocytosis of nano drugs into tumor cells.

Semiconductor small molecule IHIC/ITIC applied to photothermal therapy and photoacoustic imaging of tumors

Organic semiconductor small molecules IHIC and ITIC have been developed as solar cell materials, and because of their strong near-infrared absorption capabilities, they are promising for cancer phototherapy. This article reports the application of semiconductor small molecule IHIC/ITIC liposomes in photothermal therapy and photoacoustic imaging of tumors firstly. Experiments show that the liposome-loaded IHIC/ITIC material has good biocompatibility and can be effectively enriched in tumor sites. After being irradiated with laser, it can emit strong photoacoustic signals, and has achieved good results in the photothermal treatment of breast cancer mice. We believe that organic semiconductor small molecule IHIC/ITIC will become a promising photothermal agent with wonderful development possibilities.

A novel M2Ga2GeO7:N3+(M = Ca, Ba, Sr; N = Cr, Nd, Er) sub-micron phosphor with multiband NIR emissions: preparation, structure, properties, and LEDs

Near-infrared (NIR) emission materials can be widely applied in various fields, such as food detection, imaging, treatment, electronic products. With the trend of miniaturization of equipment, smaller materials are needed. In this work, we successfully synthesized a series of M₂Ga₂GeO₇:N³⁺(M = Ca, Ba, Sr; N = Cr, Nd, Er) samples and then focused on the study of Nd³⁺doped Sr₂Ga₂GeO₇(SGGO). A series of SGGO:xNd³⁺sub-micron phosphors were prepared via a microwave-assisted sol-gel process combined with subsequent calcination at 750 ℃, and the structural information and luminescent properties were systematically studied. SGGO is a representative tetragonal crystal and belonging to the space group of P4¯21m (113). The Nd³⁺ions occupy eight-coordinated Sr²⁺sites in the crystal lattice. From SEM analysis, the average particle size distribution is 219.7 ± 41.4 nm. The sub-micron phosphors have rich excitation spectra ranging from 350 nm to 850 nm and can produce multiband NIR emissions of 1331, 1056, and 905 nm when excited by ultraviolet and NIR light. The maximum emission intensity was obtained by optimizing the doping ratio of Nd³⁺ions. A commercial chip was then utilized to fabricate light-emitting diodes (LEDs) to verify its application potential in NIR-II mini-LEDs. Compared with blue light LEDs, the as-prepared LEDs had good imaging penetration depth and could be clearly observed under 10 mm of chicken breast coverage. The maximum imaging penetration depth can be 33 mm.

Highly Branched Polymers Based on Poly(amino acid)s for Biomedical Application

Polymers consisting of amino acid building blocks continue to receive consideration for biomedical applications. Since poly(amino acid)s are built from natural amino acids, the same building blocks proteins are made of, they are biocompatible, biodegradable and their degradation products are metabolizable. Some amino acids display a unique asymmetrical AB2 structure, which facilitates their ability to form branched structures. This review compares the three forms of highly branched polymeric structures: structurally highly organized dendrimers, dendrigrafts and the less organized, but readily synthesizable hyperbranched polymers. Their syntheses are reviewed and compared, methods of synthesis modulations are considered and variations on their traditional syntheses are shown. The potential use of highly branched polymers in the realm of biomedical applications is discussed, specifically their applications as delivery vehicles for genes and drugs and their use as antiviral compounds. Of the twenty essential amino acids, L-lysine, L-glutamic acid, and L-aspartic acid are asymmetrical AB2 molecules, but the bulk of the research into highly branched poly(amino acid)s has focused on the polycationic poly(L-lysine) with a lesser extent on poly(L-glutamic acid). Hence, the majority of potential applications lies in delivery systems for nucleic acids and this review examines and compares how these three types of highly branched polymers function as non-viral gene delivery vectors. When considering drug delivery systems, the small size of these highly branched polymers is advantageous for the delivery of inhalable drug. Even though highly branched polymers, in particular dendrimers, have been studied for more than 40 years for the delivery of genes and drugs, they have not translated in large scale into the clinic except for promising antiviral applications that have been commercialized.

Dendrimer-based nanohybrids in cancer photomedicine

Cancer phototherapy with non-invasiveness and high therapeutical efficiency has emerged as a hot spot research in cancer management. Various nanomaterials have been involved in the development of novel photoactive agents to overcome the current limitations in cancer phototherapy. Dendrimers, as an excellent nanocarrier with unique physicochemical properties, have received extensive attention and much effort has been made in the development of dendrimer-based hybrid platforms for photomedicine applications. Dendrimers can be entrapped with photosensitive agents within their internal cavities and be surface modified with reactive molecules, constructing multifunctional nanoplatforms for cancer treatment. In this review, we concisely survey the design of several different kinds of dendrimer-based nanohybrids for cancer photomedicine applications, and provide an overview of their recent applications in molecular imaging, single-modality photothermal therapy or photodynamic therapy, combination therapy, and theranostics of cancer. In addition, we also briefly discuss the future perspectives in the area of dendrimer-based nanohybrids for cancer photomedicine.

Recent research progress in the construction of active free radical nanoreactors and their applications in photodynamic therapy

Photodynamic therapy is the most important treatment strategy in free radical therapy. However, tumor microenvironment hypoxia is a key obstacle in PDT. In order to overcome this obstacle, the strategy of in situ production of O₂/radicals by catalytic reaction in solid tumors was proposed. In recent years, it has been found that there are many oxygen-independent carbon-based free radicals that can generate toxic active free radicals under laser irradiation and lead to tumor cell death. Based on the rational design of multifunctional nano-medicine, the active free radical nano-generator has opened up a new way for the highly developed nanotechnology and tumor cooperative therapy to improve the therapeutic effect. In this paper, the research status of active free radical nano-generators, especially reactive oxygen species, including the construction mechanism of active free radical nanomaterials, is reviewed and the application of free radical nano-generators in tumor therapy is emphasized.

Dual-modal imaging-guided theranostic nanocarriers based on 2-methoxyestradiol and indocyanine green

Drug toxicity and insufficient drug dosing place a limit on the effect of chemotherapy. Optimal efficacy is achieved by exposing tumor cells to the maximum tolerated dose of a chemotherapeutic drug. In this study, we developed a strategy (graphic summary) for enhancing the therapeutic and diagnostic capabilities of known chemotherapeutics. We used a dual-mode near-infrared (NIR) fluorescence/photoacoustic imaging technology to achieve actively guided tumor targeting of the photothermal therapeutic agent indocyanine green (ICG) and the chemotherapeutic drug 2-methoxyestradiol (2-ME), which were loaded into thermosensitive liposomes (TSLs) with surface-grafted tumor-targeting peptide cRGDyk (cRGDyk-2-ME@ICG-TSLs). In vitro studies demonstrated that cRGDyk-2-ME@ICG-TSLs effectively induced drug accumulation and cytotoxicity in NIR laser-irradiated B16-F10 melanoma cells using dual targeting based on the cRGDyk peptide and temperature sensitivity. An in vivo study showed that 24 h after intravenously injecting cRGDyk-2-ME@ICG-TSLs into melanoma tumor-bearing mice, the dual-mode NIR fluorescence/photoacoustic imaging could accurately identify tumors and normal tissues. In addition, the combination of cRGDyk-2-ME@ICG-TSLs and NIR radiation suppressed tumor growth in tumor-bearing nude mice and was associated with a low risk of side effects on normal organs. Our results indicate that TSLs are a suitable drug delivery system for diagnostic and chemotherapeutic agents guided by dual-mode imaging.

Poly-tetrahydropyrimidine Antibacterial Hydrogel with Injectability and Self-Healing Ability for Curing the Purulent Subcutaneous Infection

Infections caused by pathogenic microorganisms have always been the Achilles heel in the clinic. In this work, to overcome this conundrum, we proposed an injectable multifunctional hydrogel material with outstanding antibacterial properties and self-healing properties and no adverse effects on health. The cross-linked hydrogel with three-dimensional (3D) networks was quickly formed via the dynamic Schiff base between amino-modified poly-tetrahydropyrimidine (PTHP-NH₂) and multiple vanillin polymer P(DMA-VA) in 30 s. This hydrogel composite presents effective defense against both Gram-positive and Gram-negative bacteria, especially for the pyogenic Staphylococcus aureus. Moreover, the hydrogel showed almost no hemolysis and cytotoxicity. In vivo investigations indicated that hydrogels effectively killed S. aureus and protected against deterioration of inflammation. Besides, bioimaging of mice demonstrated that the hydrogel could be completely metabolized within 16 h. In a nutshell, given its outstanding antibacterial property and biocompatibility, the novel hydrogel could be an ideal candidate for the subcutaneous infection application.

Recent advances in development of dendritic polymer-based nanomedicines for cancer diagnosis

Dendritic polymers have highly branched three-dimensional architectures, the fourth type apart from linear, cross-linked, and branched one. They possess not only a large number of terminal functional units and interior cavities, but also a low viscosity with weak or no entanglement. These features endow them with great potential in various biomedicine applications, including drug delivery, gene therapy, tissue engineering, immunoassay and bioimaging. Most review articles related to bio-related applications of dendritic polymers focus on their drug or gene delivery, while very few of them are devoted to their function as cancer diagnosis agents, which are essential for cancer treatment. In this review, we will provide comprehensive insights into various dendritic polymer-based cancer diagnosis agents. Their classification and preparation are presented for readers to have a precise understanding of dendritic polymers. On account of physical/chemical properties of dendritic polymers and biological properties of cancer, we will suggest a few design strategies for constructing dendritic polymer-based diagnosis agents, such as active or passive targeting strategies, imaging reporters-incorporating strategies, and/or internal stimuli-responsive degradable/enhanced imaging strategies. Their recent applications in in vitro diagnosis of cancer cells or exosomes and in vivo diagnosis of primary and metastasis tumor sites with the aid of single/multiple imaging modalities will be discussed in great detail. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > in vivo Nanodiagnostics and Imaging Diagnostic Tools > in vitro Nanoparticle-Based Sensing.

Comparison of Structure and Local Dynamics of Two Peptide Dendrimers with the Same Backbone but with Different Side Groups in Their Spacers

In this paper, we perform computer simulation of two lysine-based dendrimers with Lys-2Lys and Lys-2Gly repeating units. These dendrimers were recently studied experimentally by NMR (Sci. Reports, 2018, 8, 8916) and tested as carriers for gene delivery (Bioorg. Chem., 2020, 95, 103504). Simulation was performed by molecular dynamics method in a wide range of temperatures. We have shown that the Lys-2Lys dendrimer has a larger size but smaller fluctuations as well as lower internal density in comparison with the Lys-2Gly dendrimer. The Lys-2Lys dendrimer has larger charge but counterions form more ion pairs with its NH 3 + groups and reduce the bare charge and zeta potential of the first dendrimer more strongly. It was demonstrated that these differences between dendrimers are due to the lower flexibility and the larger charge (+2) of each 2Lys spacers in comparison with 2Gly ones. The terminal CH 2 groups in both dendrimers move faster than the inner CH 2 groups. The calculated temperature dependencies of the spin-lattice relaxation times of these groups for both dendrimers are in a good agreement with the experimental results obtained by NMR.

Liposomes modified with bio-substances for cancer treatment

In recent years, liposomes have been used in the field of biomedicine and have achieved many significant results.