Effect of PEGylation on the physicochemical and pharmacokinetic characteristics of bovine serum albumin-encapsulated liposome

There is now little doubt that PEGylation is useful and is in widespread use because it provides a prolonged half-life,a higher stability and a lowerimmunogenicity[1].However,it is of concern that PEGylation may affect the physicochemical and pharmacokinetic characteristics of protein-encapsulated liposome.Thus,we prepared the bovine serum albumin(BSA)-encapsulated liposome(BSA-liposome)with or without PEG and then compared their physicochemical and pharmacokinetic characteristics(Fig.1).BSA-liposomes were prepared by the thin-film hydration method.

Dynamic micelles with detachable PEGylation at tumoral extracellular pH for enhanced chemotherapy

Although surface PEGylation of nanomedicines can decrease serum protein adsorption in vivo,it also blocks uptake by tumor cells.This dilemma could be overcome by employing detachably PEGylated strategy at tumoral extracellular microenvironment to achieve improved cellular uptake while prolonged circulation times.Herein,the amphiphilic graft copolymers with p H-sensitive ortho ester-linked m PEG in side chains and polyurethanes in backbone,can self-assemble into the free and doxorubicin(DOX)-loaded micelles.The p H-sensitive micelles could undergo several characteristics as follows:(i)PEGylated shells for stability in sodium dodecyl sulfonate(SDS)solution;(ii)De PEGylation via degradation of ortho ester linkages at tumoral extracellular pH(6.5)for gradually dynamic size changes and effective release of DOX;and(iii)enhanced cellular uptake and cytotoxicity via positive DOX.Moreover,the dynamic micelles with detachable PEGylation could quickly penetrate the centers of SH-SY5 Y multicellular spheroids(MCs)and strongly inhibit tumor growth in vitro and in vivo,and might be considered as promising and effective drug carriers in tumor therapy.

PEGylation of Hirudin and Analysis of Its Antithrombin Activity in vitro

Hirudin is the most anticoagulant drug found in nature, but its short serum half-life significantly inhibits its clinical anpplication. The PEGvlation of hirudin, the most promising anticoagulant drug, was performed in this paper. The optimal reaction conditions for PEG ylated hirudin were investigated, wh.en the PEGylation react, on.wasconducted under 4℃ after 10h, in the borate buffer at pH 8.5 .with the molar ratio 230 ： 1 of PEG to hirudin, a higher modification extent was achieved. Finally, the bioactivity of PEGylated hirudin was measured in vitro.Compared with unmodified hirudin, 26% of anti-thrombin activity was retained.

Site-specific PEGylation of lidamycin and its antitumor activity

In this study,N-terminal site-specific mono-PEGylation of the recombinant lidamycin apoprotein(r LDP) of lidamycin(LDM) was prepared using a polyethyleneglycol(PEG) derivative(Mw20 k Da) through a reactive terminal aldehyde group under weak acidic conditions(p H 5.5).The biochemical properties of m PEG-r LDP-AE,an enediyne-integrated conjugate,were analyzed by SDSPAGE,RP-HPLC,SEC-HPLC and MALDI-TOF.Meanwhile,in vitro and in vivo antitumor activity of m PEG-r LDP-AE was evaluated by MTT assays and in xenograft model.The results indicated that m PEGr LDP-AE showed significant antitumor activity both in vitro and in vivo.After PEGylation,m PEG-r LDP still retained the binding capability to the enediyne AE and presented the physicochemical characteristics similar to that of native LDP.It is of interest that the PEGylation did not diminish the antitumor efficacy of LDM,implying the possibility that this derivative may function as a payload to deliver novel tumortargeted drugs.

Circumvent PEGylation dilemma by implementing matrix metalloproteinase-responsive chemistry for promoted tumor gene therapy

Surface modification by poly(ethylene glycol)(PEGylation)has been acknowledged as a powerful strategy in minimizing non-specific reactions for biomedical devices.Once applied into manufacture of drug/gene delivery systems,PEGylation has demonstrated to significantly improve their biocompatibility and stealthiness in physiological environment.Nonetheless,reluctant cell membrane affinities thus cellular uptake efficiencies owing to PEGylation brought up further issues that are imperative to be resolved.Pertain to this PEGylation dilemma,we attempted to introduce peptide(GPLGVRG)linkage between block copolymer of PEG-poly{N’-[N-(2-aminoethyl)-2-aminoethyl]aspartamide}PAsp(DET),wherein the cationic PAsp(DET)could self-assemble with pDNA into nanoscaled complex core.Noteworthy was the peptide linkage whose amino acids sequence could be specifically recognized and degraded by matrix metalloproteinases(MMPs)(overexpressed in extracellular milieu of tumors).Therefore,our subsequent studies validated facile detachment of PEGylation from the aforementioned polyplex micelles upon treatment of MMPs,which elicited improved cytomembrane affinities and cellular uptake efficiencies.In addition,promoted escape from endosome entrapment was also confirmed through direct endosome membrane destabilization by PAsp(DET),which was further elucidated to be attributable to dePEGylation as well as elevated charged density of PAsp(DET)in acidic endosomes.These benefits from dePEGylation eventually contributed to promoted gene expression at the affected cells and potent tumor growth suppression based on anti-angiogenic approach.Therefore,our developed strategy has provided a facile approach in overcoming the dilemma of PEGylation,which could be informative in design of drug/gene delivery systems.

Site-specific PEGylation of Human Growth Hormone by Mutated Sortase A

Human growth hormone（hGH）, a classic therapeutic protein, which promotes growth and wound healing, is released from the pituitary gland. As a protein drug, its short half-life is its main barrier to therapeutic efficacy. Various strategies have been designed to prolong its serum half-life, the most conunon of which is the conjugation with polyethylene glycol（PEG）, as this has been shown to significantly extend protein＇s serum half-life. However, PEGylation often results in random conjugation, which can lead to impaired protein function and hinder purification, characterization and evaluation of the PEGylated protein. Therefore, site specific PEGylation is a promising direction for PEG-protein conjugation. Here we took advantages of the mutated sortase A（7M） enzyme, which can enzymati- cally ligate the universal a-amino acids to a C-terminal tagged protein. This then allows specific modification of the C-terminal of hGH with PEG. This site-specific bound PEG-hGH has similar efficacy, receptor binding and cell proliferation as wild-type hGH; however, pharmacokinetic analysis demonstrates that its serum half-life is almost 24 times that of wild-type hGH. Herein, we provided a promising advancement in the development of site specific PEGylated therapeutic proteins.

Unraveling the Impact of Direct-Acting Antivirals on Hepatitis-Linked Cirrhosis: A Comprehensive Analysis of Fibrosis, Child Score, and Disease Progression

The treatment of hepatitis C has undergone a significant boom since the advent of direct acting antivirals (DAA). Indeed, the interferon-ribavirin combination that has been used to treat hepatitis C has a virological response in only 45% of cases with significant side effects. The advent of direct-acting antivirals has changed the prognosis of cirrhotic patients with hepatitis C. DAAs have ensured a sustained viral response in the majority of patients. Our work aims to see the evolution of hepatitis C patients at the cirrhosis stage under DAA. We conducted a retrospective study over 15 years (January 2009, January 2024) including all patients with post-viral cirrhosis C, whom we divided into two groups: group A, cirrhotic patients who received ribavirin and interferon, and group B, patients on DAA. From January 2009 to January 2024, we conducted a study of 182 patients with viral hepatitis C, including 102 cirrhotic patients. The mean age was 55 years. 66% of patients were initially treated with the ribavirin interferon combination, while 34% received direct-acting antivirals (DAAs). Since the introduction of DAAs, the most commonly used regimens have been sofosbuvir/daclatasvir with or without ribavirin and sofosbuvir/ledipasvir with or without ribavirin. Group A achieved sustained virological response (SVR) in 60% of cases, with notable side effects. In Group B, SVR was 98.18%, with improved tolerability and fewer side effects than previous treatments. Fifteen patients developed hepatocellular carcinoma (HCC), with a significantly lower mortality rate in those treated with DAAs compared with pegylated dual therapy (p: 0.001).

PEGylation of therapeutic oligonucletides： From linear to highly branched PEG architectures

PEGylation, the attachment of poly（ethylene glycol） （PEG）, has been adopted to improve the pharmacokinetic properties of oligonucleotide therapeutics for nearly 30 years. Prior efforts mainly focused on the investigation of linear or slightly branched PEG having different molecular weights, terminal functional groups, and possible oligonucleotide sites for functionalization. Recent studies on highly branched PEG （including brush, star, and micellar structures） indicate superior properties in several areas including cellular uptake, gene regulation efficac~ reduction of side effects, and biodistribution. This review focuses on comparing the effects of PEG architecture on the physiochemical and biological properties of the PEGylated oligonucleotide.

Poly(L-glutamic acid)-cisplatin nanoformulations with detachable PEGylation for prolonged circulation half-life and enhanced cell internalization

PEGylation has been widely applied to prolong the circulation times of nanomedicines via the steric shielding effect,which consequently improves the intratumoral accumulation.However,cell uptake of PEGylated nanoformulations is always blocked by the steric repulsion of PEG,which limits their therapeutic effect.To this end,we designed and prepared two kinds of poly(L-glutamic acid)-cisplatin(PLG-CDDP)nanoformulations with detachable PEG,which is responsive to specific tumor tissue microenvironments for prolonged circulation time and enhanced cell internalization.The extracellular pH(pHe)-responsive cleavage 2-propionic-3-methylmaleic anhydride(CDM)-derived amide bond and matrix metalloproteinases-2/9(MMP-2/9)-sensitive degradable peptide PLGLAG were utilized to link PLG and PEG,yielding pHe-responsive PEG-pHe-PLG and MMP-sensitive PEG-MMP-PLG.The corresponding smart nanoformulations PEG-pHe-PLG-Pt and PEG-MMP-PLG-Pt were then prepared by the complexation of polypeptides and cisplatin(CDDP).The circulation half-lives of PEG-pHe-PLG-Pt and PEG-MMP-PLG-Pt were about 4.6 and 4.2 times higher than that of the control PLG-Pt,respectively.Upon reaching tumor tissue,PEG on the surface of nanomedicines was detached as triggered by pHe or MMP,which increased intratumoral CDDP retention,enhanced cell uptake,and improved antitumor efficacy toward a fatal high-grade serous ovarian cancer(HGSOC)mouse model,indicating the promising prospects for clinical application of detachable PEGylated nanoformulations.

Predictive Value of Serum pgRNA on HBeAg Clearance in Patients with Chronic Hepatitis B with Low HBeAg Levels Treated with Pegylated Interferon

Objective:To study the predictive value of serum pregenomic RNA(pgRNA)on HBeAg clearance in patients with chronic hepatitis B with low HBeAg levels during pegylated interferon therapy.Methods:Twenty chronic hepatitis B patients with HBeAg positive and quantitative<50S/CO were selected for this study.The subjects underwent pegylated interferon therapy for 48-96 weeks and were followed up in the outpatient clinic after treatment.The patients were then divided into groups based on whether their HbeAg turned negative.The predictive ability of each indicator for HBeAg negative conversion was evaluated in the HBeAg negative group and the HBeAg positive group.Results:The results of logistic regression analysis suggested that pgRNA and HBcrAg were better indicators for predicting the clearance of HBeAg after treatment.Conclusion:For patients with chronic hepatitis B with low HBeAg levels,pgRNA is a good indicator in predicting HBeAg clearance during pegylated interferon therapy.

Liposome based drug delivery as a potential treatment option for Alzheimer’s disease

Alzheimer’s disease is a neurodegenerative condition leading to atrophy of the brain and robbing nearly 5.8 million individuals in the United States age 65 and older of their cognitive functions.Alzheimer’s disease is associated with dementia and a progressive decline in memory,thinking,and social skills,eventually leading to a point that the individual can no longer perform daily activities independently.Currently available drugs on the market temporarily alleviate the symptoms,however,they are not successful in slowing down the progression of Alzheimer’s disease.Treatment and cures have been constricted due to the difficulty of drug delivery to the blood-brain barrier.Several studies have led to identification of vesicles to transport the necessary drugs through the blood-brain barrier that would typically not achieve the targeted area through systemic delivered medications.Recently,liposomes have emerged as a viable drug delivery agent to transport drugs that are not able to cross the blood-brain barrier.Liposomes are being used as a component of nanoparticle drug delivery;due to their biocompatible nature;and possessing the capability to carry both lipophilic and hydrophilic therapeutic agents across the blood brain barrier into the brain cells.Studies indicate the importance of liposomal based drug delivery in treatment of neurodegenerative disorders.The idea is to encapsulate the drugs inside the properly engineered liposome to generate a response of treatment.Liposomes are engineered to target specific diseased moieties and also several surface modifications of liposomes are under research to create a clinical path to the management of Alzheimer’s disease.This review deals with Alzheimer’s disease and emphasize on challenges associated with drug delivery to the brain,and how liposomal drug delivery can play an important role as a drug delivery method for the treatment of Alzheimer’s disease.This review also sheds some light on variation of liposomes.Additionally,it emphasizes on the liposomal formulations which are currently researched or used for treatment of Alzheimer’s disease and also discusses the future prospect of liposomal based drug delivery in Alzheimer’s disease.

Synthesis and Characterization of PEG-scuteilarin Conjugates,a Potential PEG Ester Prodrug for the Oral Delivery of Scutellarin

Highly water soluble esters of scutellarin with variable molecular weight polyethylene glycol （PEG） were prepared via PEGylation. The physicochemical properties and the stabilities under different conditions were investigated. By PEG modification, the greatly increased water solubility and desirable partition coefficient of scuteUarin were obtained, and the results showed that these conjugates were potential prodrugs for the oral delivery of scuteUarin.

Impact of the amount of PEG on prodrug nanoassemblies for efficient cancer therapy

PEGylation has been widely used to improve the pharmacokinetic properties of prodrug self-assembled nanoparticles(prodrug-SANPs).However,the impacts of the amount of PEG on the self-assemble stability,cellular uptake,pharmacokinetics,and antitumor efficacy of prodrug-SANPs are still unknown.Herein,selenoether bond bridged docetaxel dimeric prodrug was synthesized as the model prodrug.Five prodrug-SANPs were designed by using different mass ratios of prodrugs to PEG(W_(prodrug)/W_(DSPE-mPEG2000)=10:0,9:1,8:2,7:3 and 6:4),and defined as Pure drug NPs,9:1NPs,8:2NPs,7:3 NPs and 6:4 NPs,respectively.Interestingly,8:2 NPs formed the most compact nanostructure,thus improving the self-assemble stability and pharmacokinetics behavior.In addition,the difference of these prodrug-SANPs in cellular uptake was investigated,and the influence of PEG on cytotoxicity and antitumor efficacy was also clarified in details.The 8:2 NPs exhibited much better antitumor efficacy than other prodrug-SANPs and even commercial product.Our findings demonstrated the pivotal role of the amount of PEG on prodrug-SANPs.

Comparisons of biophysical properties and bioactivities of mono-PEGylated endostatin and an endostatin analog

Background:Endostatin(ES) is a well-established potent endogenous antiangiogenic factor.An ES variant,called zinc-binding protein-ES(ZBP-ES),is clinically available;however,its use is limited by rapid renal clearance and short residence time.PEGylation has been exploited to overcome these shortcomings,and mono-PEGylated ES(called M_2ES) as well as mono-PEGylated ZBP-ES(MZBP-ES) are developed in our study.This study aimed to compare the biophysical properties and biological effects of M_2ES and MZBP-ES to evaluate their druggability.Methods:Circular dichroism and tryptophan emission fluorescence were used to monitor the conformational changes of M_2ES and MZBP-ES.Their resistance to trypsin digestion and guanidinium chloride(GdmCl)-induced unfolding was examined by Coomassie staining and tryptophan emission fluorescence,respectively.The biological effects of M_2ES and MZBP-ES on endothelial cell migration were evaluated using Transwell migration and wound healing assays,and the uptake of M_2ES and MZBP-ES in endothelial cells was also compared by Western blotting and immunofluorescence.Results:Structural analyses revealed that M_2ES has a more compact tertiary structure than MZBP-ES.Moreover,M_2ES was more resistant to trypsin digestion and GdmCI-induced unfolding compared with MZBP-ES.In addition,although M_2ES and MZBP-ES showed comparable levels of inhibiting transwell migration and wound healing of endothelial cells,M_2ES displayed an increased ability to enter cells compared with MZBP-ES,possibly caused by the enhanced interaction with nucleolin.Conclusions:M_2ES has a more compact tertiary structure,is more stable for trypsin digestion and GdmCI-induced unfolding,exhibits increased cellular uptake and shows equivalent inhibitory effects on cell migration relative to MZBP-ES,indicating that M_2ES is a more promising candidate for anticancer drug development compared with MZBP-ES.

Development of a novel multi-functional integrated bioconjugate effectively targeting K-Ras mutant pancreatic cancer

Folate receptor(FR)overexpression occurs in a variety of cancers,including pancreatic cancer.In addition,enhanced macropinocytosis exists in K-Ras mutant pancreatic cancer.Furthermore,the occurrence of intensive desmoplasia causes a hypoxic microenvironment in pancreatic cancer.In this study,a novel FR-directed,macropinocytosis-enhanced,and highly cytotoxic bioconjugate folate(F)-human serum albumin(HSA)-apoprotein of lidamycin(LDP)-active enediyne(AE)derived from lidamycin was designed and prepared.F-HSA-LDP-AE consisted of four moieties:F,HSA,LDP,and AE.F-HSA-LDP presented high binding efficiency with the FR and pancreatic cancer cells.Its uptake in wild-type cells was more extensive than in K-Ras mutant-type cells.By in vivo optical imaging,F-HSA-LDP displayed prominent tumor-specific biodistribution in pancreatic cancer xenograft-bearing mice,showing clear and lasting tumor localization for 360 h.In the MTT assay,F-HSA-LDP-AE demonstrated potent cytotoxicity in three types of pancreatic cancer cell lines.It also induced apoptosis and caused G2/M cell cycle arrest.F-HSALDP-AE markedly suppressed the tumor growth of AsPc-1 pancreatic cancer xenografts in athymic mice.At well-tolerated doses of 0.5 and 1 mg/kg,(i.v.,twice),the inhibition rates were 91.2%and 94.8%,respectively(P<0.01).The results of this study indicate that the F-HSA-LDP multi-functional bioconjugate might be effective for treating K-Ras mutant pancreatic cancer.

Preparation and Characterization of Cationic PLGA-PEG-Lf/DOPE Nanoparticles for HO-1 Gene Delivery

Cationic nanoparticles （NPs） for gene delivery were successfully prepared by assembling earboxylation poly（lactic-co-glycolic acid） （PLGA）, polyethylene glycol （PEG）, L-ct-Phosphatidylethanolamine （DOPE） and octadecyl quaternized carboxymethyl chitosans （OQCMC）. Lactoferrin （Lf） was selected as a targeting ligand conjugated to PLGA via bifunctional PEG, yielding PLGA-PEG-Lf/DOPE NPs to be used for gene vectors. Fourier transform infrared spectroscopy （FTIR）, UV and nuclear magnetic resonance （NMR） spectroscopy were performed to evaluate the synthesis of the vectors. The characteristics of the vectors loaded heine oxygenase （HO-1） gene were evaluated by transmission electron microscope （TEM）, particle size analyser and fluorescent microscopy. The experimental results showed that the obtained vectors were spherical in shape with average particle size of 142.2 nm and zeta potentials of ＋16.4 inV. The vectors could protect the loaded gene from the degradation by nuclease. For 293T cells, there is high transfection efficiency of the vectors similar to liposome-2000. It can be concluded that the established cationic PLGA-PEG-Lf/DOPE NPs have potential gene delivery ability for gene therapy.

Antibody fragments: Prolonging circulation half-life special issue-antibody research

Antibodies are currently the fastest growing class of therapeutic proteins. When antibody fragments are included, there are over thirty-five antibody-based medicines approved for human therapy. Many more antibody and antibody-like fragments are being evaluated clinically. Production of antibody fragments can be efficient and their compact size can allows for better tissue extravasation into solid tumors than full antibodies. Unfortunately, a key limitation of antibody fragments for systemic use is their short half-life in circulation. Prolonging their circulation half-life can be accomplished clinically by the covalent conjugation of the antibody fragment to the water-soluble polymer, poly(ethylene glycol) (PEG). Many polymers and strategies are also being pursued to increase antibody fragment half-life.

Thermal characterisation of PEGylated mucin

Objective:To investigate the characteristics of PEGylated mucin and its potential usage. Methods:Mucin was extracted from giant African land snails and PECylated mucin was prepared with different ratios of PEG 2000-Mwt and mucin（1:1,0:1,2:1,1:3 and 3:1 to form batch A-E） using solvent technique.The physicochemical properties of mucin were identified and the solubility of mucin was assessed.The thermal properties of PEGylated mucin were measured by differential scanning calorimetry（DSC）.Results:Carbohydrates,proteins and trace amounts of fats were present in snail mucin.The mucin powder was water-soluble at 30℃and more water-soluble at 35℃but not soluble;in acetone,ethanol,0.1 M NaOH,0.1M H2SO4 and 0.1 NH4OH was water-soluble.The melting point Tm ranged from 58.58℃to 61.17℃, crystallization temperature Tc 37.08℃to 39.83℃,and glass transition temperature Tg 126.85℃to 138.39℃.The variation in Tm,Tc,and Tg with the composition in the PEGylaton showed that an interaction between PEG and mucin occured.Conclusions:This result can serve as a basis for further evaluation of the PEGylation method and be used for drug delivery.

Delivery of docetaxel using pH-sensitive liposomes based on D-α-tocopheryl poly(2-ethyl-2-oxazoline) succinate:Comparison with PEGylated liposomes

This study aimed to investigate the ability of the novel materials D-α-tocopheryl poly(2-ethyl-2-oxazoline) succinate(TPOS) to construct pH-sensitive liposomes. TPOS was initially synthesized and characterized by TLC, FTIR, and ~1H-NMR. The buffering capacity of polyethylene glycol-distearoyl phosphatidylethanolamine(PEG-DSPE) and TPOS was determined by acid-base titration, and TPOS displayed a slower downtrend and gentler slope of titration curve than PEG-DSPE within pH 7.4–5.0. Studies on the in vitro drug release demonstrated that TPOS modified docetaxel(DOC) liposomes(TPOS-DOC-L) had a slower drugrelease rate at pH 7.4 similar to PEGylated-DOC liposomes(PEG-DOC-L), whereas the release rate reached approximately 86.92% ± 1.69% at pH 6.4. In vitro cellular uptake assays by microplate reader, and flow cytometry revealed that TPOS modified coumarin 6 liposomes(TPOS-C6-L) had stronger cellular uptake at pH 6.4 than that at pH 7.4( P < 0.01). Conversely, for PEGylated C6 liposomes(PEG-C6-L) and conventional C6 liposomes(C6-L), very similar cellular uptakes were exhibited at different pH values. Confocal laser scanning microscopy images showed that PEG-C6-L and C6-L were mainly located in lysosomes. By contrast, TPOS-C6-L showed broader cytoplasmic release and distribution at 4 h. MTT assay showed that the cytotoxicity of TPOS-DOC-L was similar to that of PEG-DOC-L and conventional DOC liposomes(DOC-L) at the same DOC concentration and at pH 7.4, but was much lower than those at pH 6.4 after 48 h of incubation. The apoptosis of PEG-DOC-L and DOC-L had no remarkable improvement with decreased pH from 7.4 to 6.4. Meanwhile, TPOS-DOC-Lsignificantly induced the apoptosis of HeLa cells with decreased pH. Therefore, TPOS can be a biomaterial for the construction of a pH-sensitive drug delivery system.

Synthesis of Amine Terminated Pegylated Iron Oxide Nanoparticles for Prospective Astrocytoma Resection Grade Improvement

Having a survival rate to 5 years of only 3%,Glioblastoma’s(GBM)main treatment is surgical excision.Iron oxide nanoparticles have been proved to be a magnetic resonance imaging contrast agent and,if synthesized and tuned correctly,could be used to improve complete GBM resection.In this work monodisperse iron oxide nanoparticles were synthesized using thermal decomposition method,then a ligand exchange reaction with 3-aminopropyl trimethoxysilane(APS)was performed,following Pegylation of the particles using dicarboxylic acid PEG(PEG-diacid)and finally aminating with 2,2’-(ethylenedioxy)bis(ethylamine),last two by amide reactions.STEM and DLS demonstrate monodispersity(log σ<0.2)and desired size range to penetrate the blood-brain barrier(BBB);FT-IR shows the reactions were executed correctly and finally stability in deionized water,0.07 M NaCl and PBS 1X,as a function of 0-30 days,was tested.Results revealed the importance that the oleic acid/iron oleate molar ratio and the growth stage time represents for determining iron oxide nanoparticles’ size;as well as APS concentration and nucleation time influence on silica coating when performing the ligand exchange reaction.The produced iron oxide nanoparticles exhibit stability and proper amine terminated groups which are needed to allow easy incorporation of Chlorotoxin,a 36-amino acid peptide that binds specifically to astrocytoma cells,and a fluorescent molecule,which enables real time visualization of the tumor during surgery.