Self-Assembled Peptide-Based Nanomaterials for Biomedical Imaging and Therapy

99mTc-Labeled Polyethylenimine-Entrapped Gold Nanoparticles with pH-Responsive Charge Conversion Property for Enhanced Dual Mode SPECT/CT Imaging of Cancer Cells

Development of tumor dual mode contrast agents is still a great challenge due to the relative low accumulation at tumor site, which result in the poor imaging efficiency. In this study, we constructed functional technetium-99m (^99mTc) labeled polyethylenimine (PEI)-entrapped gold nanoparticles (Au PENs) with pH-responsive charge conversion property for enhanced single photon emission computed tomography (SPECT)/computed tomography (CT) dual mode imaging of cancer cells. PEI with amine functional groups (PEI.NH₂) was successively modified with monomethyl ether and carboxyl functionalized polyethylene glycol (mPEG-COOH), maleimide and succinimidyl valerate functionalized PEG (MAL-PEG-SVA), diethylenetriaminepentaacetic dianhydride (DTPA), and fluorescein isothiocyanate (FI), and used to entrapped gold nanoparticles inside, followed by conjugation with the alkoxyphenyl acylsulfonamide (APAS) through the PEG maleimide, acetylation of the PEI leftover surface amines and ^99mTc labeling. The created nanosystem with the mean Au core diameter of 3.3 nm and with a narrow size distribution displays an excellent colloidal stability and desired cytocompatibility in the investigated Au concentration range. Due to the fact that the attached APAS moieties are responsive to pH, the functionalized Au PENs with a neutral surface charge can switch to be positively charged under slightly acidic pH condition, which could improve the cellular uptake by cancer cells. With these properties, the developed functionalized Au PENs could achieve enhanced dual mode SPECT/CT imaging of cancer cells in vitro. The constructed PEI-based nanodevices may be adopted as an excellent dual mode contrast agent for SPECT/CT imaging of cancer cells of different types.

One- and two-photon responsive injectable nano-bundle biomaterials from co-assembled lipopeptides for controlling molecular diffusion

An injectable biomaterial has been prepared through co-assembly of lipopeptides C₄-Bhc-Glu-Glu-NH₂ and C₁₄-Phe-Lys-Lys-NH₂. This biomaterial contained a large number of nanofibre bundles (nano-bundles, NBs) of lipopeptide co-assemblies and performed like hydrogels. The morphologies of the NBs were observed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The rheological properties were investigated with a rheometer. Excitingly, the NB biomaterials exhibited shear thinning and self-healing properties, and could be used as injectable biomaterials. The coumarin group in the lipopeptides endowed the NB biomaterials with both ultraviolet (UV, a one photon process) and near-infrared (NIR) light (a two photon process) responsiveness. A small molecule (Doxorubicin, DOX) and a large molecule (bovine serum albumin, BSA) were used as model drugs, and both of them could be encapsulated in the NB biomaterials and could also be released sustainably or explosively under different conditions (with or without one- and two-photon irradiation). DOX and BSA have different release behaviors because of the NBs. Cell assays showed that the co-assembled NB biomaterials exhibited low cytotoxicity to normal cells. However, when DOX was loaded, the NB biomaterials could kill HeLa cells sustainably. Under UV and NIR irradiation, HeLa cells could be killed rapidly because of the burst release of DOX. The co-assembled supramolecular NB biomaterials with dual-responsiveness, tunable rheological properties and multi-drug encapsulating ability might have potential in biomedical engineering.

Assemblies of Peptides in a Complex Environment and their Applications

Using peptide assemblies with emergent properties to achieve elaborate functions has attracted increasing attention in recent years. Besides tailoring the self-assembly of peptides in vitro, peptide research is advancing into a new and exciting frontier: the rational design of peptide assemblies (or their derivatives) for biological functions in a complex environment. This Minireview highlights recent developments in peptide assemblies and their applications in biological systems. After introducing the unique merits of peptide assemblies, we discuss the recent progress in designing peptides (or peptide derivatives) for self-assembly with conformational control. Then, we describe biological functions of peptide assemblies, with an emphasis on approach-instructed assembly for spatiotemporal control of peptide assemblies, in the cellular context. Finally, we discuss the future promises and challenges of this exciting area of chemistry.

Peptide Tectonics: Encoded Structural Complementarity Dictates Programmable Self-Assembly

Programmable self-assembly of peptides into well-defined nanostructures represents one promising approach for bioinspired and biomimetic synthesis of artificial complex systems and functional materials. Despite the progress made over the past two decades in the development of strategies for precise manipulation of the self-assembly of peptides, there is a remarkable gap between current peptide assemblies and biological systems in terms of structural complexity and functions. Here, the concept of peptide tectonics for the creation of well-defined nanostructures predominately driven by the complementary association at the interacting interfaces of tectons is introduced. Peptide tectons are defined as peptide building blocks exhibiting structural complementarity at the interacting interfaces of commensurate domains and undergoing programmable self-assembly into defined supramolecular structures promoted by complementary interactions. Peptide tectons are categorized based on their conformational entropy and the underlying mechanism for the programmable self-assembly of peptide tectons is highlighted focusing on the approaches for incorporating the structural complementarity within tectons. Peptide tectonics not only provides an alternative perspective to understand the self-assembly of peptides, but also allows for precise manipulation of peptide interactions, thus leading to artificial systems with advanced complexity and functions and paves the way toward peptide-related functional materials resembling natural systems.

Fluorescent Tau-derived Peptide for Monitoring Microtubules in Living Cells

Microtubules (MTs) are key cytoskeletal components that modulate various cellular activities with their dynamic structural changes, including polymerization and depolymerization. To monitor the dynamics of MTs in living cells, many drug-based fluorescent probes have been developed; however, these also potentially disturb the polymerization/depolymerization of MTs. Here, we report nondrug, peptide-based fluorescent probes to monitor MTs in living cells. We employed a Tau-derived peptide (TP) that has been shown to bind MTs without inhibiting polymerization/depolymerization in vitro. We show that a tetramethylrhodamine (TMR)-labeled TP (TP-TMR) is internalized into HepG2 cells and binds to intracellular MTs, enabling visualization of MTs as clear, fibrous structures. The binding of TP-TMR shows no apparent effects on polymerization/depolymerization of MTs induced by MT-targeted drugs and temperature change. The main uptake mechanism of TP-TMR was elucidated as endocytosis, and partial endosomal escape resulted in the binding of TP-TMR to MTs. TP-TMR exhibited no cytotoxicity compared with MT-targeted drug scaffolds. These results indicate that TP scaffolds can be exploited as useful MT-targeted tools in living cells, such as in long-term imaging of MTs.

Semiconducting Perylene Diimide Nanostructure: Multifunctional Phototheranostic Nanoplatform

Precision medicine requires noninvasive and accurate early diagnosis and individually appropriate treatments. Phototheranostics has been considered a frontier precision medical technology to provide rapid and safe disease localization and efficient cure. Harnessing the power of advanced nanomedicine with photonics, phototheranostics is rapidly developing and progressively becoming irreplaceable in modern medicine. Nanoscale semiconducting materials, such as inorganic semiconductors, organic conjugated polymers, and small molecules with photonic properties, have been extensively explored in medical imaging (fluorescence imaging, optical coherence tomography, and photoacoustic [PA] imaging) and phototherapy (photothermal, photodynamic, and photocontrolled combination therapies). In practical clinical applications, organic semiconducting materials, because of their biocompatibility and natural metabolism, are preferred over inorganic materials for phototheranostics. Supramolecular self-assembly is considered a significant method for preparing organic detachable and multifunctional phototheranostics, as supramolecular interactions, such as π-π interactions, hydrogen bonding, hydrophobic effects, and electrostatic interactions, are non-covalent and dynamic. Developing new and effective organic supramolecular phototheranostics requires exploration of well-designed basic building blocks with optical properties, understanding of the assembly at the nanoscale, and optimization of the phototheranostics with unique and distinctive multifunctional efficacy. In this Account, we summarize our recent work on the development of small molecular semiconducting perylene diimide (SPDI) for advanced phototheranostics. SPDI is modified to have strong near-infrared absorption beyond 700 nm by the push-pull electronic effect and owns the merits of remarkable photostability, large extinction coefficient, and high photothermal conversion efficiency. By hydrophilic modification, the amphiphile can self-assemble into a nanomicellar structure that allows PA imaging and can serve as a photothermal conversion agent. After theranostics delivery is achieved, this SPDI can be further functionalized for multimodality imaging and photothermally triggered multimodal synergistic therapy. Several well-designed asymmetric structures of SPDI can be obtained by stepwise modification of imides. It is noteworthy that the self-assembly of SPDI is controllable, allowing the preparation of different-sized spherical nanoparticles and rodlike nanoparticles and nanodroplets. For biomedical applications of SPDI phototheranostics (SPDIPTs), the size effect of SPDIPTs has been highlighted in lymph node mapping and cancer imaging. The PA properties and targeting peptide modification of SPDIPTs have brought about the ultrasensitive imaging of early thrombus. The supramolecular nanoconstructs of SPDIPTs further permit multimodality-imaging-guided cancer therapy. In brief, the design of SPDIPTs considers synthetic chemistry, supramolecular self-assembly, nanotechnology, and photonics. Furthermore, SPDIPTs have diverse biomedical applications and offer many opportunities for advancing nanomedicine.

Peptide-modulated self-assembly as a versatile strategy for tumor supramolecular nanotheranostics

Advances in supramolecular self-assembly have promoted the development of theranostics, the combination of both therapeutic and diagnostic functions in a single nanoplatform, which is closely associated with antitumor applications and has shown promising potential in personalized medicine. Peptide-modulated self-assembly serves as a versatile strategy for tumor supramolecular nanotheranostics possessing controllability, programmability, functionality and biosafety, thus promoting the translation of nanotheranostics from bench to bedside. In this review, we will focus on the self-assembly of peptide-photosensitizers and peptide-drugs as well as multicomponent cooperative self-assembly for the fabrication of nanotheranostics that integrate diagnosis and therapeutics for antitumor applications. Emphasis will be placed on building block design, interaction strategies and the potential relationships between their structures and properties, aiming to increase understanding of the critical role of peptide-modulated self-assembly in advancing antitumor supramolecular nanotheranostics.

Bioinspired Multivalent Peptide Nanotubes for Sialic Acid Targeting and Imaging-Guided Treatment of Metastatic Melanoma

Tumor metastasis is considered a major cause of cancer-related human mortalities. However, it still remains a formidable challenge in clinics. Herein, a bioinspired multivalent nanoplatform for the highly effective treatment of the metastatic melanoma is reported. The versatile nanoplatform is designed by integrating indocyanine green and a chemotherapeutic drug (7-ethyl-10-hydroxycamptothecin) into phenylboronic acid (PBA)-functionalized peptide nanotubes (termed as I/S-PPNTs). I/S-PPNTs precisely target tumor cells through multivalent interaction between PBA and overexpressed sialic acid on the tumor surface in order to achieve imaging-guided combination therapy. It is demonstrated that I/S-PPNTs are efficiently internalized by the B16-F10 melanoma cells in vitro in a PBA grafting density-dependent manner. It is further shown that I/S-PPNTs specifically accumulate and deeply penetrate into both the subcutaneous and lung metastatic B16-F10 melanoma tumors. More importantly, I/S-PPNT-mediated combination chemo- and photodynamic therapy efficiently eradicates tumor and suppresses the lung metastasis of B16-F10 melanoma in an immunocompetent C57BL/6 mouse model. The results highlight the promising potential of the multivalent peptide nanotubes for active tumor targeting and imaging-guided cancer therapy.

Synthetic Biology for Multiscale Designed Biomimetic Assemblies: From Designed Self-Assembling Biopolymers to Bacterial Bioprinting

Nature is based on complex self-assembling systems that span from the nanoscale to the macroscale. We have already begun to design biomimetic systems with properties that have not evolved in nature, based on designed molecular interactions and regulation of biological systems. Synthetic biology is based on the principle of modularity, repurposing diverse building modules to design new types of molecular and cellular assemblies. While we are currently able to use techniques from synthetic biology to design self-assembling molecules and re-engineer functional cells, we still need to use guided assembly to construct biological assemblies at the macroscale. We review the recent strategies for designing biological systems ranging from molecular assemblies based on self-assembly of (poly)peptides to the guided assembly of patterned bacteria, spanning 7 orders of magnitude.

Using Self-Assembling Peptides to Integrate Biomolecules into Functional Supramolecular Biomaterials

Throughout nature, self-assembly gives rise to functional supramolecular biomaterials that can perform complex tasks with extraordinary efficiency and specificity. Inspired by these examples, self-assembly is increasingly used to fabricate synthetic supramolecular biomaterials for diverse applications in biomedicine and biotechnology. Peptides are particularly attractive as building blocks for these materials because they are based on naturally derived amino acids that are biocompatible and biodegradable; they can be synthesized using scalable and cost-effective methods, and their sequence can be tailored to encode formation of diverse architectures. To endow synthetic supramolecular biomaterials with functional capabilities, it is now commonplace to conjugate self-assembling building blocks to molecules having a desired functional property, such as selective recognition of a cell surface receptor or soluble protein, antigenicity, or enzymatic activity. This review surveys recent advances in using self-assembling peptides as handles to incorporate biologically active molecules into supramolecular biomaterials. Particular emphasis is placed on examples of functional nanofibers, nanovesicles, and other nano-scale structures that are fabricated by linking self-assembling peptides to proteins and carbohydrates. Collectively, this review highlights the enormous potential of these approaches to create supramolecular biomaterials with sophisticated functional capabilities that can be finely tuned to meet the needs of downstream applications.

A Multifunctional Peptide-Conjugated AIEgen for Efficient and Sequential Targeted Gene Delivery into the Nucleus

Gene therapy has immense potential as a therapeutic approach to serious diseases. However, efficient delivery and real-time tracking of gene therapeutic agents have not been solved well for successful gene-based therapeutics. Herein we present a versatile gene-delivery strategy for efficient and visualized delivery of therapeutic genes into the targeted nucleus. We developed an integrin-targeted, cell-permeable, and nucleocytoplasmic trafficking peptide-conjugated AIEgen named T_D NCP for the efficient and sequential targeted delivery of an antisense single-stranded DNA oligonucleotide (ASO) and tracking of the delivery process into the nucleus. As compared with T_D NCP/siRNA-NPs (siRNA functions mainly in the cytoplasm), T_D NCP/ASO-NPs (ASO functions mainly in the nucleus) exhibited a better interference effect, which further indicates that T_D NCP is a nucleus-targeting vector. Moreover, T_D NCP/ASO-NPs showed a favorable tumor-suppressive effect in vivo.

Addressable Peptide Self-Assembly on the Cancer Cell Membrane for Sensitizing Chemotherapy of Renal Cell Carcinoma

Chemotherapy has been validated unavailable for treatment of renal cell carcinoma (RCC) in clinic due to its intrinsic drug resistance. Sensitization of chemo-drug response plays a crucial role in RCC treatment and increase of patient survival. Herein, a recognition-reaction-aggregation (RRA) cascaded strategy is utilized to in situ construct peptide-based superstructures on the renal cancer cell membrane, enabling specifically perturbing the permeability of cell membranes and enhancing chemo-drug sensitivity in vitro and in vivo. First, P1-DBCO can specifically recognize renal cancer cells by targeting carbonic anhydrase IX. Subsequently, P2-N₃ is introduced and efficiently reacts with P1-DBCO to form a peptide P3, which exhibits enhanced hydrophobicity and simultaneously aggregates into a superstructure. Interestingly, the superstructure retains on the cell membrane and perturbs its integrity/permeability, allowing more doxorubicin (DOX) uptaken by renal cancer cells. Owing to this increased influx, the IC₅₀ is significantly reduced by nearly 3.5-fold compared with that treated with free DOX. Finally, RRA strategy significantly inhibits the tumor growth of xenografted mice with a 3.2-fold enhanced inhibition rate compared with that treated with free DOX. In summary, this newly developed RRA strategy will open a new avenue for chemically engineering cell membranes with diverse biomedical applications.

Recent advances of self-assembling peptide-based hydrogels for biomedical applications

Peptide-based hydrogels have been proven to be preeminent biomedical materials due to their high water content, tunable mechanical stability, great biocompatibility and excellent injectability. The ability of peptide-based hydrogels to provide extracellular matrix-mimicking environments opens up opportunities for their biomedical applications in fields such as drug delivery, tissue engineering, and wound healing. In this review, we first describe several methods commonly used for the fabrication of robust peptide-based hydrogels, including spontaneous hydrogelation, enzyme-controlled hydrogelation and cross-linking-enhanced hydrogelation. We then introduce some representative studies on their applications in drug delivery and antitumor therapy, antimicrobial and wound healing materials, and 3D bioprinting and tissue engineering. We hope that this review facilitates the advances of hydrogels in biomedical applications.

Bispyrene-Based Self-Assembled Nanomaterials: In Vivo Self-Assembly, Transformation, and Biomedical Effects

Self-assembled nanomaterials show potential high efficiency as theranostic agents for high-performance imaging and therapy. However, superstructures and properties of preassembled nanomaterials are somewhat compromised under complicated physiological conditions. Given the advantages of the dynamic nature and adaptive behavior of self-assembly systems, we propose an "in vivo self-assembly" strategy for in situ construction of nanomaterials in living objects. For the proof-of-concept study of in vivo self-assembly, we developed a bispyrene (BP) molecule as a multifunctional building block. BP molecules show nonfluorescence in the monomeric state. Quantum-chemical calculations indicate that BP forms twisted intramolecular charge transfer states, which are separated into two orthogonal units, preventing the fluorescence emission. Interestingly, the typical excimeric emission of BP is observed with the formation of J-type aggregates, as confirmed by single-crystal X-ray diffraction. Packing of the BP molecules generates parallel pyrene units that interact with adjacent ones in a slipped face-to-face fashion through intermolecular π-π interactions. BP and/or its amphiphilic derivatives are capable of self-aggregating into nanoparticles (NPs) in aqueous solution because of the hydrophobic and π-π interactions of BP. Upon specific biological stimuli, BP NPs can be transformed into variable self-assembled superstructures. Importantly, the self-assembled BP NPs exhibit turn-on fluorescence signals that can be used to monitor the self-assembly/disassembly process in vitro and in vivo. On the basis of the photophysical properties of BP and its aggregates, we synthesized a series of designed BP derivatives as building blocks for in situ construction of functional nanomaterials for bioimaging and/or therapeutics. We observed several new biomedical effects, e.g., (i) the assembly/aggregation-induced retention (AIR) effect, which shows improved accumulation and retention of bioactive nanomaterials in the regions of interests; (ii) the transformation-induced surface adhesion (TISA) effect, which means the BP NPs transform into nanofibers (NFs) on cell surfaces upon binding with specific receptors, which leads to less uptake of BP NPs by cells via traditional endocytosis pathway; and (iii) transformation of the BP NPs into NFs in the tumor microenvironment, showing high accumulation and long-term retention, revealing the transformation-enhanced accumulation and retention (TEAR) effect. In this Account, we summarize the fluorescence property and emission mechanism of BP building blocks upon aggregation in the biological environment. Moreover, BP-derived compounds used for in vivo self-assembly and transformation are introduced involving modulation strategies. Subsequently, unexpected biomedical effects and applications for theranostics of BP based nanomaterials are discussed. We finally conclude with an outlook toward future developments of BP-based self-assembled nanomaterials.

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

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

Peptide-functionalized NaGdF4 nanoparticles for tumor-targeted magnetic resonance imaging and effective therapy

Metallic nanoparticles showed potent efficacy for diagnosis and therapy of cancer, but their clinical applications are limited by their poor tumor-targeting ability. Herein, peptide-functionalized 9 nm NaGdF₄ nanoparticles (termed as, NaGdF₄@bp-peptide NPs) have been synthesized through the Gd–phosphate coordination reaction of the spherical NaGdF₄ nanoparticles with phosphopeptides (sequence: KLAKLAKKLAKLAKG(p-S)GAKRGARSTA, p-S means phosphorylated serine) including a p32 protein binding motif incorporating a cell-penetrating function, and a proapoptotic domain. The NaGdF₄@bp-peptide NPs are ready to be efficiently internalized by cancer cells; they show a much higher cytotoxicity in MCF-7 breast cancer cells than the casein phosphopeptide (CPP) modified NaGdF₄ nanoparticles (termed as, NaGdF₄@CPP NPs). Using mouse-bearing MCF-7 breast cancer as a model system, the in vivo experimental results demonstrate that NaGdF₄@bp-peptide NPs have integration of T₁-weighted magnetic resonance imaging (MRI) contrast and tumor-targeting functionalities, and are able to suppress tumor growth without causing systemic toxicity.

NaGdF₄@bp-peptide nanoparticles have been used as a T₁-weighted MR contrast agent with active-tumor targeting and antitumor ability.

Enzyme-instructed self-assembly of a novel histone deacetylase inhibitor with enhanced selectivity and anticancer efficiency

A novel peptide-based prodrug molecule could be activated in situ via ALP catalysis and further self-assembled into a nanodrug with enhanced selectivity and anticancer efficacy.

A self-delivery system based on an amphiphilic proapoptotic peptide for tumor targeting therapy

A self-delivery system KDH was constructed to realize tumor targeting therapy, and it possessed extraordinary therapeutic efficacy both in vitro and in vivo.

Lanthanum phosphate/chitosan scaffolds enhance cytocompatibility and osteogenic efficiency via the Wnt/β-catenin pathway

BACKGROUND

Fabrication of porous scaffolds with great biocompatibility and osteoinductivity to promote bone defect healing has attracted extensive attention.

METHODS

In a previous study, novel lanthanum phosphate (LaPO4)/chitosan (CS) scaffolds were prepared by distributing 40- to 60-nm LaPO4 nanoparticles throughout plate-like CS films.

RESULTS

Interconnected three dimensional (3D) macropores within the scaffolds increased the scaffold osteoconductivity, thereby promoting cell adhesion and bone tissue in-growth. The LaPO4/CS scaffolds showed no obvious toxicity and accelerated bone generation in a rat cranial defect model. Notably, the element La in the scaffolds was found to promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) through the Wnt/β-catenin signalling pathway and induced high expression of the osteogenesis-related genes alkaline phosphatase, osteocalcin and Collagen I (Col-I). Moreover, the LaPO4/CS scaffolds enhanced bone regeneration and collagen fibre deposition in rat critical-sized calvarial defect sites.

CONCLUSION

The novel LaPO4/CS scaffolds provide an admirable and promising platform for the repair of bone defects.

Turning a Luffa Protein into a Self-Assembled Biodegradable Nanoplatform for Multitargeted Cancer Therapy

The peptide-derived self-assembly platform has attracted increasing attention for its great potential to develop into multitargeting nanomedicines as well as its inherent biocompatibility and biodegradability. However, their clinical application potentials are often compromised by low stability, weak membrane penetrating ability, and limited functions. Herein, inspired by a natural protein from the seeds of Luffa cylindrica, we engineered via epitope grafting and structure design a hybrid peptide-based nanoplatform, termed Lupbin, which is capable of self-assembling into a stable superstructure and concurrently targeting multiple protein-protein interactions (PPIs) located in cytoplasm and nuclei. We showed that Lupbin can efficiently penetrate cell membrane, escape from early endosome-dependent degradation, and subsequently disassemble into free monomers with wide distribution in cytosol and nucleus. Importantly, Lupbin abrogated tumor growth and metastasis through concurrent blockade of the Wnt/β-catenin signaling and reactivation of the p53 signaling, with a highly favorable in vivo biosafety profile. Our strategy expands the application of self-assembled nanomedicines into targeting intercellular PPIs, provides a potential nanoplatform with high stability for multitargeted cancer therapy, and likely reinvigorates the development of peptide-based therapeutics for the treatment of different human diseases including cancer.

Neglected Hydrophobicity of Dimethanediyl Group in Peptide Self-Assembly: A Hint from Amyloid-like Peptide GNNQQNY and Its Derivatives

Besides typical hydrophobic amino acids providing hydrophobic interactions, glutamine as a hydrophilic amino acid has also been known to be an important element in many self-assembling peptides, but it is still not clear how this particular amino acid contributes to the self-assembling process. We supposed that the dimethanediyl group in the side chain of glutamine could provide hydrophobic interaction for peptide self-assembly. To prove this hypothesis, we used the GNNQQNY peptide and its derivatives as examples to show the importance of the dimethanediyl group for peptide self-assembly. We found a very close relationship between the number of dimethanediyl groups, the strength of hydrophobic interaction, and the self-assembling ability of the peptides, indicating the hydrophobicity of the dimethanediyl group and its important role for self-assembly. This new finding might be instructive for clarifying the self-assembling mechanism of many natural peptides, as well as for developing novel self-assembling peptide nanomaterials.

Self-Assembled Fluorescent Organic Nanomaterials for Biomedical Imaging

Fluorescent nanomaterials, self-assembled from building blocks through multiple intermolecular interactions show diversified structures and functionalities, and are potential fluorescence contrast agents/probes for high-performance biomedical imaging. Self-assembled nanomaterials exhibit high stability, long circulation time, and targeted biological distribution. This review summarizes recent advances of self-assembled nanomaterials as fluorescence contrast agents/probes for biomedical imaging. The self-assembled nanomaterials are classified into two groups, i.e., ex situ and in situ construction of self-assembled nanomaterials. The advantages of ex situ as well as in situ constructed nanomaterials for biomedical applications are discussed thoroughly. The directions of future developments for self-assembled nanomaterials are provided.

A bioactive implant in situ and long-term releases combined drugs for treatment of osteoarticular tuberculosis

Anti-tuberculosis chemotherapy with a long duration and adequate dosing is the mainstay for treatment of osteoarticular tuberculosis (TB). However, it is difficult for systemic administration to reach adequate local drug concentrations and achieve effective treatment. Herein, a hydroxyapatite (HA) scaffold implant combined with a drug-releasing system was designed to achieve in situ and long-term anti-TB drug release and highly efficient therapeutic activity in vitro and in vivo. The clinical anti-TB drugs hydrophilic isoniazid (INH) and hydrophobic rifampicin (RFP) were molecularly dispersed into polyvinyl alcohol (PVA) through immersion-curing techniques and were steadily adhered onto the surfaces of HA scaffolds (HA-drug@PVA). The HA-drug@PVA scaffolds showed a long-term, sustained drug release profile and killed proliferating Mycobacterium in vitro. In vivo experimental results revealed that the HA-drug@PVA scaffolds provided over 10- and 100-fold higher concentrations in muscles and bones, respectively, as well as a much lower concentration (<0.025) in blood. Furthermore, the HA-drug@PVA scaffold implanted in an osteoarticular TB rabbit model showed obvious bone regeneration and fusion due to the inhibition of TB-associated inflammatory changes. The excellent therapeutic effects indicate that in situ implant materials combined with a long-term drug release system are promising for the treatment of osteoarticular TB and other osteoarticular infections.

Enzyme-triggered self-assembly of gold nanoparticles for enhanced retention effects and photothermal therapy of prostate cancer

A peptide-modified gold nanoparticle was developed for tumour-targeted therapy.