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Background: Immunotherapy has profoundly changed the landscape of cancer management and represented the most significant breakthrough. Yet, it is a formidable challenge that the majority of cancers - the so-called "cold" tumors - poorly respond to immunotherapy. To find a general immunoregulatory modality that can be applied to a broad spectrum of cancers is an urgent need. Methods: Magnetic hyperthermia (MHT) possesses promise in cancer therapy. We develop a safe and effective therapeutic strategy by using magnetism-mediated targeting MHT-immunotherapy in "cold" colon cancer. A magnetic liposomal system modified with cell-penetrating TAT peptide was developed for targeted delivery of a CSF1R inhibitor (BLZ945), which can block the CSF1-CSF1R pathway and reduce M2 macrophages. The targeted delivery strategy is characterized by its magnetic navigation and TAT-promoting intratumoral penetration. Results: The liposomes (termed TAT-BLZmlips) can induce ICD and cause excessive CRT exposure on the cell surface, which transmits an "eat-me" signal to DCs to elicit immunity. The combination of MHT and BLZ945 can repolarize M2 macrophages in the tumor microenvironment to relieve immunosuppression, normalize the tumor blood vessels, and promote T-lymphocyte infiltration. The antitumor effector CD8+ T cells were increased after treatment. Conclusion: This work demonstrated that TAT-BLZmlips with magnetic navigation and MHT can remodel tumor microenvironment and activate immune responses and memory, thus inhibiting tumor growth and recurrence.

Development of superparamagnetic iron oxide nanoparticles (SPIONs) based theranostics has suffered due to its self-contradictory requirements on water dispersity and drug loadings. Generally well-dispersed SPIONs have excellent MRI performance but are insensitive to magnetism mediated delivery. Besides, loading hydrophobic drugs also hampers the stability of SPIONs which is critical for their biomedical applications. Considering these aspects, we employed curcumin as a cross-linking agent to facilitate the modular assembly of drug and monodisperse SPIONs (Cur/ALN-β-CD-SPIONs). Interestingly, the saturation magnetization of Cur/ALN-β-CD-SPIONs is higher than that of ALN-β-CD-SPIONs, and the value of r2 indicating the negative contrast ability increases to 389.96 mM-1 s-1. Furthermore, the Cur/ALN-β-CD-SPIONs are very stable in PBS buffer over 3 weeks. The mice treated with Cur/ALN-β-CD-SPIONs by tail vein injection displayed a better tumor inhibition effect than that of free curcumin. This study provides a simple method for modular assembly of drug and monodisperse SPIONs, which is crucial to the design of SPIONs with superior T2-imaging performance and drug delivery.

Development of superparamagnetic iron oxide nanoparticles (SPIONs) based theranostics has suffered due to its self-contradictory requirements on water dispersity and drug loadings. Generally well-dispersed SPIONs have excellent MRI performance but are insensitive to magnetism mediated delivery. Besides, loading hydrophobic drugs also hampers the stability of SPIONs which is critical for their biomedical applications. Considering these aspects, we employed curcumin as a cross-linking agent to facilitate the modular assembly of drug and monodisperse SPIONs (Cur/ALN-β-CD-SPIONs). Interestingly, the saturation magnetization of Cur/ALN-β-CD-SPIONs is higher than that of ALN-β-CD-SPIONs, and the value of

Macrophages are sentinels of the immune system, which are often hijacked by tumor cells to assist tumor growth and metastasis. Herein our results showed that low dose salinomycin (SAL) in the range of 10-50 nM could efficiently induce M1 macrophage polarization in a dose- and time- dependent manner in vitro, with 30 nM SAL being optimal to generate M1-type macrophages from RAW246.7 cells. In animal study, intratumorally injected SAL (50 µg/kg) increased proportion of CD86 cells (by 28.9%), and decreased CD206 cells (by 14.2%) in transplant 4T1 tumors, in comparison with PBS group. Thus it resulted in significant regression in tumor growth (20% tumor inhibition) and pulmonary metastasis (reduced the number of metastatic nodes by 58%) in SAL group, whereas lipopolysaccharide (LPS) and paclitaxel (PTX) groups showed comparable number of metastatic lesions and volume of tumor. LPS treatment could as well lead to inflammatory reactions in tumor with SAL group, but resulted in systemic inflammation (elevated levels of IL-1α, IL-1β and TNF-α in serum), and PTX (10 μg/kg) treatment increased both types of macrophages. For the first time, we employed salinomycin below the dose of direct antitumor activity could effectively prime M1 type macrophage stimulation and regress tumor growth and metastasis.

In this paper, we prepared a dual functional system based on dextrin-coated silver nanoparticles which were further attached with iron oxide nanoparticles and cell penetrating peptide (Tat), producing Tat-modified Ag-Fe3O4 nanocomposites (Tat-FeAgNPs). To load drugs, an –SH containing linker, 3-mercaptopropanohydrazide, was designed and synthesized. It enabled the silver carriers to load and release doxorubicin (Dox) in a pH-sensitive pattern. The delivery efficiency of this system was assessed in vitro using MCF-7 cells, and in vivo using null BalB/c mice bearing MCF-7 xenograft tumors. Our results demonstrated that both Tat and externally applied magnetic field could promote cellular uptake and consequently the cytotoxicity of doxorubicin-loaded nanoparticles, with the IC50 of Tat-FeAgNP-Dox to be 0.63 µmol/L. The in vivo delivery efficiency of Tat-FeAgNP carrying Cy5 to the mouse tumor was analyzed using the in vivo optical imaging tests, in which Tat-FeAgNP-Cy5 yielded the most efficient accumulation in the tumor (6.7±2.4% ID of Tat-FeAgNPs). Anti-tumor assessment also demonstrated that Tat-FeAgNP-Dox displayed the most significant tumor-inhibiting effects and reduced the specific growth rate of tumor by 29.6% (P = 0.009), which could be attributed to its superior performance in tumor drug delivery in comparison with the control nanovehicles., Graphical abstract A dual functional system was prepared based on dextrin-coated silver nanoparticles (AgNPs) which were further attached with iron oxide nanoparticles and cell penetrating peptide (Tat). The dual functionalized Tat-FeAgNPs could sufficiently target tumor by magnetism assisted tumor retention and Tat helped tissue penetration.fx1

Two distinct macrophage phenotypes contribute to kidney injury and repair during the progression of renal interstitial fibrosis; proinflammatory (M1) and antiinflammatory (M2) macrophages. Legumain, an asparaginyl endopeptidase of the cysteine protease family, is overexpressed in macrophages in some pathological conditions. However, the macrophage subtype and function of macrophage-derived legumain remains unclear. To resolve this we tested whether M2 macrophages contribute to the accumulation of legumain in the unilateral ureteral obstruction model. Legumain-null mice exhibited more severe fibrotic lesions after obstruction compared with wild-type control. In vitro, IL4-stimulated M2 polarization led to the overexpression and secretion of legumain. The levels of fibronectin and collagen I/III, major components of the extracellular matrix, were reduced in the conditioned medium of TGF-β1-stimulated tubular epithelial cells or fibroblasts after treatment with legumain or conditioned medium from IL4-stimulated macrophages. Administration of the legumain inhibitor RR-11a exacerbated fibrotic lesions following obstruction. Therapeutically, adoptive transfer of legumain-overexpressing macrophages or IL4-stimulated macrophages ameliorated the deposition of collagen and fibronectin induced by ureteral obstruction, either in the wild-type mice or in lgmn–/– mice. Thus, M2 macrophages overexpress and secret legumain and legumain mediates the anti-fibrotic effect of M2 macrophages in obstructive nephropathy.

RNAi technology has aroused wide public interest due to its high efficiency and specificity to treat multiple types of diseases. However, the effective delivery of siRNA remains a challenge due to its large molecular weight and strong anionic charge. Considering their remarkable functions in vivo and features that are often desired in drug delivery carriers, biomimetic systems for siRNA delivery become an effective and promising strategy. Based on this, covalent attachment of synthetic cell penetrating peptides (CPP) to siRNA has become of great interest. We developed a monomeric covalent conjugate of low molecular weight protamine (LMWP, a well-established CPP) and siRNA via a cytosol-cleavable disulfide linkage using PEG as a crosslinker. Results showed that the conjugates didn't generate coagulation, and exhibited much better RNAi potency and intracellular delivery compared with the conventional charge-complexed CPP/siRNA aggregates. Three different synthetic and purification methods were compared in order to optimize synthesis efficiency and product yield. The methodology using hetero-bifunctional NHS–PEG–OPSS as a crosslinker to synthesize LMWP–siRNA simplified the synthesis and purification process and produced the highest yield. These results pave the way towards siRNA biomimetic delivery and future clinical translation., Graphical abstract A monomeric covalent conjugate of low molecular weight protamine (LMWP, a well-established CPP) and siRNA were developed via a cytosol-cleavable disulfide linkage using PEG as a crosslinker. Three different synthetic and purification methods were compared and hetero-bifunctional NHS–PEG–OPSS was the optimized crosslinker.fx1

Matrix metalloproteinases (MMPs) activatable imaging probe has been explored for tumor detection. However, activation of the probe is mainly done in the extracellular space without intracellular uptake of the probe for more sensitivity. Although cell-penetrating peptides (CPPs) have been demonstrated to enable intracellular delivery of the imaging probe, they nevertheless encounter off-target delivery of the cargos to normal tissues. Herein, we have developed a dual MMP-2-activatable and tumor cell-permeable magnetic nanoprobe to simultaneously achieve selective and intracellular tumor imaging. This novel imaging probe was constructed by self-assembling a hexahistidine-tagged (His-tagged) fluorescent fusion protein chimera and nickel ferrite nanoparticles via a chelation mechanism. The His-tagged fluorescent protein chimera consisted of a red fluorescent protein mCherry that acted as the fluorophore, the low-molecular-weight protamine peptide as the CPP, and the MMP-2 cleavage sequence fused with the hexahistidine tag, whereas the nickel ferrite nanoparticles functioned as the His-tagged protein binder and also the fluorescent quencher. Both in vitro and in vivo results revealed that this imaging probe would not only remain nonpermeable to normal tissues, thereby offsetting the nonselective cellular uptake, but was also suppressed of fluorescent signals during magnetic tumor-targeting in the circulation, primarily because of the masking of the CPP activity and quenching of the fluorophore by the associated NiFe

Vinpocetine was a BCS II drug, whose clinical applications had suffered from low oral bioavailability because of its inefficient dissolution in the GI tract. As the dissolution rate depended on the surface area of the drug crystals, we herein explored shape-controlled recrystallization via antisolvent process as an excipient-free strategy to improve the bioavailability of VIN. By adjusting the water/ethanol ratio, initial VIN concentration, and temperatures, morphologies of the crystalline products could be finely tuned from three-dimensional cubes and tubes, to two-dimensional frizzled plates, and finally to zero-dimensional microparticle clusters. Morphology analysis and in situ FBRM surveillance of the growing process suggested that a diffusion-limited crystal growth mechanism was responsible for the shape variation of VIN products. Finally, we tested the in vitro dissolution efficiency as well as the in vivo bioavailability of recrystallized VIN crystals. Results manifested that the tubular crystal sh...

An anticancer drug delivery system consisting of DNA nanoparticles synthesized by rolling circle amplification (RCA) was developed for prostate cancer membrane antigen (PSMA) targeted cancer therapy. The template of RCA was a DNA oligodeoxynucleotide coded with PSMA-targeted aptamer, drug-loading domain, primer binding site and pH-sensitive spacer. Anticancer drug doxorubicin, as the model drug, was loaded into the drug-loading domain (multiple GC-pair sequences) of the DNA nanoparticles by intercalation. Due to the integrated pH-sensitive spacers in the nanoparticles, in an acidic environment, the cumulative release of doxorubicin was far more than the cumulative release of the drug in the normal physiological environment. In cell uptake experiments, treated with doxorubicin loaded DNA nanoparticles, PSMA-positive C4-2 cells could take up more doxorubicin than PSMA-null PC-3 cells. The prepared DNA nanoparticles showed the potential as drug delivery system for PSMA targeting prostate cancer therapy.

Coating supermagnetic iron oxide nanoparticles (SPIOs) with albumin would not only improve their in vivo stability but also improve their drug loading capacity, but current methods are either inefficient or time consuming. Herein, a single step synthesis of bovine serum albumin (BSA)-stabilized SPIOs with high dispersity and stability via a modified co-precipitation method is reported. The benefits of albumin for coating of SPIOs, i.e. its long circulation life, low immunogenicity and drug binding ability to specific binding domains, were all retained in our mildly modified BSA. The BSA-SPIOs thus prepared displayed an excellent T2 contrast enhancing effect and drug loading capacity. Two cytotoxic drugs curcumin and sunitinib, where the former is a drug-resistance depressor and the latter is a tyrosine kinase inhibitor, were further co-loaded into the BSA-SPIOs (denoted SPIO-SC) to achieve combined synergistic therapy. SPIO-SC formulations displayed the most significant tumor inhibition yet least drug-induced toxicity both in vitro and in vivo when compared with free drug formulations. Through in vivo pharmacokinetic analysis, it was demonstrated that SPIO-SC most efficiently delivered the encapsulated drugs to the tumor site, and at the same time maintained the originally designed, optimal ratios of curcumin to sunitinib concentrations at the tumor target and yielded the most optimal synergistic effect and, subsequently, the more effective therapeutic outcomes. The prepared BSA-SPIOs are an extremely promising candidate for both MR imaging and drug delivery as a healthcare material.

Brain is the most complex organ in human body. The prevalence of CNS diseases and their associated secondary diseases has become the growing threat and huge disease burden to the global society. Most medications in treating brain diseases have failed to yield significant therapeutic outcomes because of the impermeable membrane barriers lying between the brain and the circulation system, the blood-brain barrier (BBB). As a result, the brain drug delivery imposes a global challenge in the development of more effective CNS medications. In this chapter, the anatomic features, brain circulation, as well as the brain microenvironment, are described in details. Apart from the BBB, other obstacles involved in brain drug delivery also attribute to the diffusion problems and cell selectivity. To address these issues, a number of nanomaterial-based techniques, including cell-penetrating peptide-based permeation-enhancing strategy and receptor-mediated targeting delivery, which have been widely explored to improving the delivery efficiency of brain drugs, are discussed in the second part of this chapter.

While drug resistance appears to be an inevitable problem of an increasing number of anticancer drugs in monotherapy, combination drug therapy has become a prosperous method to reduce the administered total drug dosages as well as overcome the drug resistance of carcinoma cells. Curcumin, considered to possess multifaceted roles in cancer treatment according to its multiple anti-neoplastic mechanisms as a depressor of chemoresistance, can significantly facilitate its anti-cancer functions and improve therapeutic effects via combination usage with a variety of other drugs with different reaction mechanisms. To explore this possibility, four anti-cancer chemotherapeutic agents that all possess a certain degree of drug resistance problems, including three tyrosine kinase inhibitors (erlotinib, sunitinib and sorafenib) that are acting on different cell pathways and a typical anticancer drug doxorubicin, were combined with curcumin individually to examine the synergistic anti-tumor effect both in vitro and in vivo. Results revealed that sunitinib combined with curcumin at the molar ratio of 0.46 yielded the most potent synergistic effect in vitro, and was therefore chosen for further animal evaluation. To further enhance the anticancer effect, bovine serum albumin (BSA) nanoparticles were utilized as a carrier to deliver the selected drug combination in situ. Preliminary in vivo findings confirmed our hypothesis of being able to maintain a similar injected drug ratio for prolonged time periods in tested animals by our approach, thereby maximizing the therapeutic potency yet minimizing the toxicity of these drugs. This work could open up a new avenue on combination drug therapy and realization the clinical utility of such drugs.

We investigated the influence of particle shape and solubility on the caking behavior of trisodium phosphate by considering the adhesion free energy and crystal bridge theory. Caking of trisodium phosphate during the drying process under static conditions is a two-step process: adhesion followed by crystal bridge formation between particles. The adhesion free energy plays an important role in adhesion. Trisodium phosphate particles cannot adhere to each other and cake when the adhesion free energy is greater than a critical value, which varies with particle shape. Compared with granular particles, cylindrical particles have larger contact area between particles, which results in more crystal bridges forming and a higher caking ratio. Thus, the critical value is about 100 mJ/m 2 for cylindrical particles, but 60 mJ/m 2 for granular particles at 25 °C. Concerning the solubility, when particles are similar shapes and soluble in the rinsing liquid, the caking ratio has a linear relationship with adhesion free energy. However, if the particles are insoluble in the rinsing liquid, caking can be completely prevented regardless of adhesion free energy because no crystal bridges form during the growth process. Hence, caking of trisodium phosphate particles could be inhibited by screening rinsing liquids, and optimizing the particle shape and size distribution.

Brain delivery of macromolecular therapeutics (e.g., proteins) remains an unsolved problem because of the formidable blood–brain barrier (BBB). Although a direct pathway of nose-to-brain transfer provides an answer to circumventing the BBB and has already been intensively investigated for brain delivery of small drugs, new challenges arise for intranasal delivery of proteins because of their larger size and hydrophilicity. In order to overcome the barriers and take advantage of available pathways (e.g., epithelial tight junctions, uptake by olfactory neurons, transport into brain tissues, and intra-brain diffusion), a low molecular weight protamine (LMWP) cell-penetrating peptide was utilized to facilitate nose-to-brain transport. Cell-penetrating peptides (CPP) have been widely used to mediate macromolecular delivery through many kinds of biobarriers. Our results show that conjugates of LMWP–proteins are able to effectively penetrate into the brain after intranasal administration. The CPP-based intranasal method highlights a promising solution for protein therapy of brain diseases., Graphical abstract The low molecular weight protamine (LMWP) cell-penetrating peptide is utilized to mediate proteins for nose-to-brain transport. The conjugates of LMWP–proteins can effectively penetrate into the brains by noninvasive intranasal administration. The cell penetrating peptide-based intranasal method highlights a promising solution for protein therapy for brain diseases. fx1

Transcutaneous immunization (TCI) is an attractive vaccination strategy for targeting the epidermal dendritic cells (DCs). TCI has been widely explored for protection against infectious diseases. Recently, its promising application in cancer immunotherapy has also attracted great attention. However, effective percutaneous delivery of the vaccines must overcome the formidable stratum corneum, as well as specifically target DCs; both are big challenges. We developed the mannosylated grafted cell-penetrating peptide-low molecular weight PEI copolymer (CPP-PEI1800-Man) with the combination of microneedles for DC-targeting percutaneous delivery of DNA vaccine for malignant melanoma (MM) therapy. Mannose receptors are overexpressed on the surface of DCs. The microneedle-assisted in vivo skin penetration of the CPP-PEI1800-Man/DNA nanoparticles was investigated, and the DC-targeting efficiency was measured. The induction of protective and therapeutic anti-tumor immunity by the CPP-PEI1800-Man/DNA nanoparticles was significantly enhanced compared to the PEI25k/DNA vaccines. Transcutaneous vaccination with the microneedle-assisted CPP-PEI1800-Man/DNA efficiently promoted Trp2-specific cellular immune responses, resulting in effective protection against B16 melanoma challenge in BALB/c mice. Importantly, the CPP-PEI1800-Man/DNA nanoparticles strongly induced CD8+ cytotoxic T lymphocyte activity and CD4+ T cells that secreted the interferon-γ and interleukin-12 cytokines against melanoma cells. As a result, cancer growth was inhibited and the survival time of B16-xenografted BALB/c mice was prolonged. Therefore, the CPP-PEI1800-Man copolymer is promising for DC-specific vaccination, and microneedle-assisted CPP-PEI1800-Man/DNA delivery represents a potential immunotherapeutic strategy for MM.

Multidrug resistance (MDR) is a major obstacle to successful cancer treatment and is crucial to cancer metastasis and relapse. Combination therapy is an effective strategy for overcoming MDR. However, the different pharmacokinetic (PK) profiles of combined drugs often undermine the combination effect in vivo, especially when greatly different physicochemical properties (e.g., those of macromolecules and small drugs) combine. To address this issue, nanotechnology-based codelivery techniques have been actively explored. They possess great advantages for tumor targeting, controlled drug release, and identical drug PK profiles. Thus, a powerful tool for combination therapy is provided, and the translation from in vitro to in vivo is facilitated. In this review, we present a summary of various combination strategies for overcoming MDR and the nanotechnology-based combination therapy.

A novel high drug loading pH-cleavable polymer hybrid nanoparticle was prepared via doxorubicin (DOX) grafted onto PEGylated, mussel-inspired polydopamine (PDA) and then coated onto hollow silica nanoparticles for drug delivery. A series of characterization shed light on the formation mechanisms of PDA coatings on hollow silica. We hypothesized that dopamine was first absorbed onto the surface of hollow silica and then began self-polymerization. A Dox-containing thiol moiety was fabricated with conjugation between doxorubicin hydrochloride and Mercaptopropionyalkali with a pH-cleavable hydrozone bond. Using a Michael addition reaction, several Dox-containing thiol moieties were grafted onto the surface of the PDA. The drug loading capacity can reach 35.43%. It can minimize the metabolic problem of silica. The released behavior of Dox can be significantly enhanced at endosomal pH compared to physiological pH. After folate modification, nanoparticles can lead to more cellular endocytosis. Meanwhile animal assays showed that more Dox accumulated in tumor tissue, which can enhanced the cytotoxicity to 4T1 cancer cells with a targeting group compared to free DOX and untargeted groups. Meanwhile, the tumor growth was significantly inhibited. This promising material shows a promising future as a drug delivery system.

Because of the unparalleled efficiency and universal utility in treating a variety of disease types, siRNA agents have evolved as the future drug-of-choice. Yet, the inability of the polyanionic siRNA macromolecules to cross the cell membrane remains as the bottleneck of possible clinical applications. With the cell penetrating peptides (CPP) being discovered lately, the most effective tactic to achieve the highest intracellular siRNA delivery deems to be by covalently conjugating the drug to a CPP; for instance, the arginine-rich Tat or low molecular weight protamine (LMWP) peptides. However, construction of such a chemical conjugate has been referred by scientists in this field as the "Holy Grail" challenge due to self-assembly of the cationic CPP and anionic siRNA into insoluble aggregates that are deprived of the biological functions of both compounds. Based on the dynamic motion of PEG, we present herein a concise coupling strategy that is capable of permitting a high-yield synthesis of the cell-permeable, cytosol-dissociable LMWP-siRNA covalent conjugates. Cell culture assessment demonstrates that this chemical conjugate yields by far the most effective intracellular siRNA delivery and its corresponded gene-silencing activities. This work may offer a breakthrough advance towards realizing the clinical potential of all siRNA therapeutics and, presumably, most anionic macromolecular drugs such as anti-sense oligonucleotides, gene compounds, DNA vectors and proteins where conjugation with the CPP encounters with problems of aggregation and precipitation. To this end, the impact of this coupling technique is significant, far-reaching and wide-spread.

For the past 20 years, we have witnessed an unprecedented and, indeed, rather miraculous event of how cell-penetrating peptides (CPPs), the naturally originated penetrating enhancers, help overcome the membrane barrier that has hindered the access of bio-macromolecular compounds such as genes and proteins into cells, thereby denying their clinical potential to become potent anti-cancer drugs. By taking the advantage of the unique cell-translocation property of these short peptides, various payloads of proteins, nucleic acids, or even nanoparticle-based carriers were delivered into all cell types with unparalleled efficiency. However, non-specific CPP-mediated cell penetration into normal tissues can lead to widespread organ distribution of the payloads, thereby reducing the therapeutic efficacy of the drug and at the same time increasing the drug-induced toxic effects. In view of these challenges, we present herein a review of the new designs of CPP-linked vehicles and strategies to achieve highly effective yet less toxic chemotherapy in combating tumor oncology.

The tetra-peptide AVPI, derived from the Smac/DIABLO N-terminal epitope, is able to trigger caspase activation and apoptotic process. However, its clinical value is greatly hampered by the nature of membrane-impermeability. Herein, the cell-penetrating chimeric apoptotic peptide of AVPIR8 is synthesized, of which the apoptosis-induced AVPI is strategically blended with the cell-penetrating sequence of octaarginine (R8). The dual-functionalized AVPIR8 is not only potent in inducing apoptosis in tumor cells due to the cell penetration ability, but also is able to work as gene carrier for transfering the tumor suppressor p53 DNA into cells, thus constructing a co-delivery drug system (AVPIR8/p53). Such system efficiently promotes apoptosis in cancer cells while sparing normal cells, and its antitumor activity is further significantly enhanced in combination with doxorubicin as cocktail therapy. More importantly, the anticancer efficacy of the cocktail is demonstrated to be able to arrest tumor growth in two animal tumor models (melanoma and cervical cancers), respectively. The chemotherapeutic dose in the AVPIR8/p53-based cocktail is significantly reduced by 80%, compared to the monotherapy of doxorubicin. The present results show the promise of the co-delivered AVPIR8/p53 as adjuvant therapy for boosting the conventional chemotherapeutics, with a unique benefit of enhanced productive treatment outcomes yet greatly reduced adverse toxicity.

Conventional chemotherapy has little or no specificity for cancer cells, normally resulting in low drug accumulation at the tumor region (inefficacy) and drug-induced severe side effects (toxicity). Nowadays, new strategies have been developed to improve both the targeting ability and cellular drug uptake using active targeting ligands and drug internalization agents, which could recognize and interact with specific receptors overexpressed on tumor cells and then trigger a drug internalization process by transporting the cargos into cells. Among those strategies, enzyme-triggered cell penetrating peptide (CPP)-mediated systems seem to be a feasible approach. The expression level of specific enzymes like proteases, esterases or glycosidases is often higher in tumor cells than in normal tissues, and such concentration gradients can be exploited as a tool for targeted cancer therapy. CPPs are known to be effective in promoting membrane transportation of the drug cargos, rendering a deeper tumor permeation that could further enhance the therapeutic efficacy of the delivered drug. An enzyme-triggered, CPP-mediated system would combine these advantages to yield a system with the enhanced tumor targeting ability and internalization efficiency and so far many systems have been successfully exploited and applied to cancer therapy. In this review, typical enzymes applied in cancer theranostic systems were firstly reviewed, followed by analyzing pros and cons of cell penetrating peptides. Most importantly, different types of applications of enzyme-triggered CPP-mediated systems in tumor imaging were illustrated. Finally, the drug loaded applications, i.e. enzyme-triggered CPP-mediated systems in drug delivery were reviewed.

A variety of methods including penetrating enhancers, enzyme inhibitors, as well as cargo mediated drug delivery have been explored to improve the intolerance of parenteral administrated insulin, but little success has been achieved so far. Under this background, cell penetrating peptides (CPPs), with their ability to enhance transport efficiency of macromolecular drugs have been demonstrated to be able to increase insulin bioavailability (BA) in a number of studies, of which a BA up to 50.7% relative to subcutaneously administered insulin could be achieved by nasal route under optimal conditions. Furthermore, CPPs could be conveniently formulated with insulin, or be grafted onto drug-loaded cargoes to facilitate the cargo mediated insulin delivery. Here we reviewed the recent achievements on CPP-mediated insulin transport, and outlined various CPP-based delivery strategies which are expected to show potential in clinical translation in the future.

Low molecular weight protamine (LMWP) is a peptide fragment produced in our laboratory from enzymatic digestion of native protamine. More than 30 papers studying the properties and applications of LMWP have been published by our group in various journals since its initial discovery in 1999. Results have shown that LMWP could completely neutralize the anticoagulant functions of both heparin and low molecular weight heparin (LMWH), with reduced antigenicity and cross-reactivity toward the mice-derived anti-protamine antibodies. Aside from its potential as a heparin/LMWH antagonist, LMWP also shows the ability to retard insulin adsorption by the formation of an insoluble complex, making it a less toxic long-lasting insulin product than the conventional neutral protamine Hagedorn (NPH) insulin for diabetic control. Importantly, LMWP (Sequence: VSRRRRRRGGRRRR), with 10 arginine residues in its structure, could function as a cell-penetrating peptide (CPP), also termed protein transduction domain (PTD), to achieve effective intracellular protein or gene delivery in clinical practice. In this paper, we present a thorough review of our work related to LMWP, with the aim of providing readers an insight into its potential to be a clinical protamine substitute as well as a non-toxic cell penetrating peptide applicable to achieve intracellular protein and gene delivery.

Given a linear stationary non-Gaussian signal, suppose that we fit a linear model using higher order statistics and one of several existing methods. The model is fitted under certain assumptions on the data and the underlying (true) model. Having obtained a model, how do we know if the fitted model is "good"? This paper is devoted to the problem of model diagnostics and validation. We propose frequency-domain tests that are applicable to both third- and fourth-order statistics based model fitting unlike existing tests. Model order selection is a byproduct of the model validation approach. Two computer simulation examples are presented to illustrate the proposed tests.

To enhance access security capability of WiMAX (Worldwide Interoperability for Microwave Access), a trusted access scheme based on identity is proposed in this paper. It adopts trusted access architecture which includes three layers: Identity Layer, Evaluation Layer and Authentication Layer. Firstly, every entity is assigned only an identity in the Identity Layer; secondly, credible attribute of the entity is evaluated in the Evaluation Layer; lastly, Authentication Layer judges the evaluation results that Evaluation Layer refers. The scheme uses Biology Authentication and mutual authentication, then controls access of the user or terminal and chooses the service strategy of service side. Security analysis indicates that the scheme can prevent unlicensed user access, unlicensed terminal access, unlicensed base station attack and message modification.

Given a linear stationary non-Gaussian signal, suppose that we fit a linear model using higher-order statistics and one of several existing methods. The model is fitted under certain assumptions on the data and the underlying (true) model. Having obtained a model, how do we know if the fitted model is "good"? This paper is devoted to the problem of model diagnostics and validation. We propose some simple frequency-domain tests that are applicable to both third-order and fourth-order statistics-based model fitting unlike existing tests. A computer simulation example is presented to illustrate the proposed tests.

Pluronic copolymer L61 was found to possess a stealth function for liposomal drug delivery, comparing favorably to PEG. The liposomes modified with 0.1% L61 (w/w) were long-circulating, and preferentially accumulated in the tumor site. The paclitaxel-loaded L61-liposomes with a single injection dose could successfully arrest the tumor growth, lasting for five days, and displayed better treatment outcomes compared to the non-modified liposomes and even the PEGylated liposomes.

Macromolecular drugs (e.g., proteins and nucleic acids) are highly environmentally liable and unstable, and their administration is strictly limited to injection. Moreover, a vast majority of macromolecules are cell membrane- impermeable, and it is a critical issue to enhance the cellular uptake efficiency for improving the treatment outcomes. Cell-penetrating peptide (CPP)-assisted strategy is promising for effective macromolecular delivery. As a case in point, CPP-mediated protein delivery has been considered as a revolutionary breakthrough. With aid of CPP, virtually all pro- teins can become cell-permeable. Generally, CPP-protein delivery works in a covalent delivery pattern, by which CPP and its cargo are linked via covalent bond. Recently, noncovalent delivery has also attracted attention for its potential application for protein delivery. In the presented work, the noncovalent pattern was demonstrated for its feasibi lity in percutaneous and nose-to-brain delivery with TAT/GFP as model drug, in comparison with the covalent method. Noncovalent CPP/protein delivery and its noninvasive application may provide a facile method for protein therapy.