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1.
Opt Express ; 32(10): 17893-17910, 2024 May 06.
Article in English | MEDLINE | ID: mdl-38858958

ABSTRACT

This paper addresses the challenge of significant interference caused by direct sunlight, which adversely affects the orientation accuracy of underwater imaging polarization sensors (IPS). A novel underwater polarization orientation method is proposed based on direct sunlight compensation. Firstly, based on the polarization transmission model at the water-air interface, the interference mechanism of the underwater direct sunlight polarization detection model was analyzed. The underwater IPS detection model based on direct sunlight compensation is constructed, which uses the weight coefficient of underwater direct sunlight to compensate for the interference on the polarization channel and improve the accuracy of underwater polarization detection models. Furthermore, the analytical solution method for the polarization state information of underwater IPS is proposed, employing the augmented Stokes vectors to construct a linear equation for solving the weight coefficients of direct sunlight and improving the computational efficiency. Finally, an underwater polarization orientation experimental platform is established, and both simulation and actual underwater experiments are conducted. Compared with the traditional methods, the proposed method reduces heading error by an average of 92.53% at different solar altitudes.

2.
Opt Express ; 32(6): 9184-9200, 2024 Mar 11.
Article in English | MEDLINE | ID: mdl-38571157

ABSTRACT

The bionic polarization sensor (PS)/MEMS inertial measurement unit (MIMU) integrated system can provide reliable attitude and heading information for unmanned vehicles in the case of GNSS rejection. However, the existing measurement methods have poor adaptability to inclining, sheltering, and other harsh environments, and do not make full use of the complementary characteristics of the gyroscopes, accelerometers, and PS, which seriously affects the system performance. Therefore, this paper proposes an attitude and heading measurement method based on an adaptive complementary Kalman filter (ACKF), which corrects the gyroscopes according to the gravity measured by the accelerometers to improve the attitude accuracy and fuses the IMU heading and tilt-compensated polarization heading by Kalman optimal estimation. On this basis, the maximum correlation entropy of the measured gravity and the theoretical gravity is used to construct an adaptive factor to realize the adaptive complementary of the gyroscopes and the accelerometers. Finally, the effectiveness of the method is verified by the outdoor rotation test without occlusion and the vehicle test with occlusion. Compared with the traditional Kalman filter, the pitch, roll, and heading RMSE of the vehicle test are reduced by 89.3%, 93.2% and, 9.6% respectively, which verifies the great advantages.

3.
Sensors (Basel) ; 22(23)2022 Nov 22.
Article in English | MEDLINE | ID: mdl-36501733

ABSTRACT

Relative pose measurement for noncooperative objects is an important part of 3D shape recognition and motion tracking. The methods based on scanning point clouds have better environmental adaptability and stability than image-based methods. However, the discrete points obtained from a continuous surface are sparse, which leads to point-to-point dislocations in the overlapping area and seriously reduces the accuracy. Therefore, this paper proposed a relative-pose-measurement algorithm based on double-constrained intersurface mutual projections. First, the initial corresponding set was constructed using mutual projections between the areas with similar feature descriptors, and then the final corresponding set was determined through the rigid-transformation-consistency constraint to improve the accuracy of the matchings and achieve a high-accuracy relative pose measurement. In the Stanford dataset, the rotation error and translation error were reduced by 19.3% and 13.4%, respectively. Furthermore, based on the proposed evaluation method, which separated the error of the pose-measurement algorithm from that of the instrument, the experiments were carried out with a self-made swept-frequency interferometer. The rotation error was reduced by 39.8%, and the surface deviation was reduced by 4.9%, which further proved the advancement of the method.

4.
Biochem Biophys Res Commun ; 560: 199-204, 2021 06 30.
Article in English | MEDLINE | ID: mdl-34000469

ABSTRACT

The specific identification and elimination of cancer cells has been a great challenge in the past few decades. In this study, the circular dichroism (CD) of cells was measured by a self-designed special system through the folate-conjugated chiral nano-sensor. A novel method was established to recognize cancer cells from normal cells according to the chirality of cells based on their CD signals. After a period of interaction between the nano-sensor and cells, the sharp weakening of CD signals was induced in cancer cells but normal cells remained unchanged. The biocompatibility of the nano-sensor was evaluated and the result showed that it exhibited significant cytotoxic activity against cancer cells while no obvious damage on normal cells. Notably, the research indicated that the nano-sensor may selectively cause apoptosis in cancer cells, and thus, have the potential to act as an antitumor agent.


Subject(s)
Cadmium Compounds , Neoplasms/therapy , Quantum Dots/chemistry , Sulfides , Tellurium , Apoptosis , Breast Neoplasms/therapy , Cell Line, Tumor , Circular Dichroism , Female , Folic Acid , Humans
5.
Bioconjug Chem ; 30(1): 148-160, 2019 01 16.
Article in English | MEDLINE | ID: mdl-30566343

ABSTRACT

Site-specific conjugation of small molecules to antibodies represents an attractive goal for the development of more homogeneous targeted therapies and diagnostics. Most site-specific conjugation strategies require modification or removal of antibody glycans or interchain disulfide bonds or engineering of an antibody mutant that bears a reactive handle. While such methods are effective, they complicate the process of preparing antibody conjugates and can negatively impact biological activity. Herein we report the development and detailed characterization of a robust photoaffinity cross-linking method for site-specific conjugation to fully glycosylated wild-type antibodies. The method employs a benzoylphenylalanine (Bpa) mutant of a previously described 13-residue peptide derived from phage display to bind tightly to the Fc domain; upon UV irradiation, the Bpa residue forms a diradical that reacts with the bound antibody. After the initial discovery of an effective Bpa mutant peptide and optimization of the reaction conditions to enable efficient conjugation without concomitant UV-induced photodamage of the antibody, we assessed the scope of the photoconjugation reaction across different human and nonhuman antibodies and antibody mutants. Next, the specific site of conjugation on a human antibody was characterized in detail by mass spectrometry experiments and at atomic resolution by X-ray crystallography. Finally, we adapted the photoconjugation method to attach a cytotoxic payload site-specifically to a wild-type antibody and showed that the resulting conjugate is both stable in plasma and as potent as a conventional antibody-drug conjugate in cells, portending well for future biological applications.


Subject(s)
Antibodies/chemistry , Cross-Linking Reagents/chemistry , Immunoconjugates/chemistry , Peptides/chemistry , Photoaffinity Labels/chemistry , Animals , Humans , Mutation , Oxidation-Reduction , Photochemical Processes , Protein Binding , Protein Conformation , Surface Plasmon Resonance
6.
Mol Pharm ; 15(9): 3979-3996, 2018 09 04.
Article in English | MEDLINE | ID: mdl-30040421

ABSTRACT

A number of cytotoxic pyrrolobenzodiazepine (PBD) monomers containing various disulfide-based prodrugs were evaluated for their ability to undergo activation (disulfide cleavage) in vitro in the presence of either glutathione (GSH) or cysteine (Cys). A good correlation was observed between in vitro GSH stability and in vitro cytotoxicity toward tumor cell lines. The prodrug-containing compounds were typically more potent against cells with relatively high intracellular GSH levels (e.g., KPL-4 cells). Several antibody-drug conjugates (ADCs) were subsequently constructed from PBD dimers that incorporated selected disulfide-based prodrugs. Such HER2 conjugates exhibited potent antiproliferation activity against KPL-4 cells in vitro in an antigen-dependent manner. However, the disulfide prodrugs contained in the majority of such entities were surprisingly unstable toward whole blood from various species. One HER2-targeting conjugate that contained a thiophenol-derived disulfide prodrug was an exception to this stability trend. It exhibited potent activity in a KPL-4 in vivo efficacy model that was approximately three-fold weaker than that displayed by the corresponding parent ADC. The same prodrug-containing conjugate demonstrated a three-fold improvement in mouse tolerability properties in vivo relative to the parent ADC, which did not contain the prodrug.


Subject(s)
Benzodiazepines/chemistry , Disulfides/chemistry , Immunoconjugates/chemistry , Prodrugs/chemistry , Pyrroles/chemistry , Cell Line, Tumor , Cysteine/metabolism , Glutathione/metabolism , Humans , Immunoconjugates/metabolism , Molecular Structure
7.
Bioconjug Chem ; 28(10): 2538-2548, 2017 10 18.
Article in English | MEDLINE | ID: mdl-28885827

ABSTRACT

The incorporation of cysteines into antibodies by mutagenesis allows for the direct conjugation of small molecules to specific sites on the antibody via disulfide bonds. The stability of the disulfide bond linkage between the small molecule and the antibody is highly dependent on the location of the engineered cysteine in either the heavy chain (HC) or the light chain (LC) of the antibody. Here, we explore the basis for this site-dependent stability. We evaluated the in vivo efficacy and pharmacokinetics of five different cysteine mutants of trastuzumab conjugated to a pyrrolobenzodiazepine (PBD) via disulfide bonds. A significant correlation was observed between disulfide stability and efficacy for the conjugates. We hypothesized that the observed site-dependent stability of the disulfide-linked conjugates could be due to differences in the attachment site cysteine thiol pKa. We measured the cysteine thiol pKa using isothermal titration calorimetry (ITC) and found that the variants with the highest thiol pKa (LC K149C and HC A140C) were found to yield the conjugates with the greatest in vivo stability. Guided by homology modeling, we identified several mutations adjacent to LC K149C that reduced the cysteine thiol pKa and, thus, decreased the in vivo stability of the disulfide-linked PBD conjugated to LC K149C. We also present results suggesting that the high thiol pKa of LC K149C is responsible for the sustained circulation stability of LC K149C TDCs utilizing a maleimide-based linker. Taken together, our results provide evidence that the site-dependent stability of cys-engineered antibody-drug conjugates may be explained by interactions between the engineered cysteine and the local protein environment that serves to modulate the side-chain thiol pKa. The influence of cysteine thiol pKa on stability and efficacy offers a new parameter for the optimization of ADCs that utilize cysteine engineering.


Subject(s)
Cysteine/chemistry , Immunoconjugates/chemistry , Benzodiazepines/chemistry , Drug Stability , Immunoconjugates/genetics , Maleimides/chemistry , Models, Molecular , Mutation , Protein Conformation , Pyrroles/chemistry
8.
Bioconjug Chem ; 28(8): 2086-2098, 2017 08 16.
Article in English | MEDLINE | ID: mdl-28636382

ABSTRACT

Conjugation of small molecule payloads to cysteine residues on proteins via a disulfide bond represents an attractive strategy to generate redox-sensitive bioconjugates, which have value as potential diagnostic reagents or therapeutics. Advancement of such "direct-disulfide" bioconjugates to the clinic necessitates chemical methods to form disulfide connections efficiently, without byproducts. The disulfide connection must also be resistant to premature cleavage by thiols prior to arrival at the targeted tissue. We show here that commonly employed methods to generate direct disulfide-linked bioconjugates are inadequate for addressing these challenges. We describe our efforts to optimize direct-disulfide conjugation chemistry, focusing on the generation of conjugates between cytotoxic payloads and cysteine-engineered antibodies (i.e., THIOMAB antibody-drug conjugates, or TDCs). This work culminates in the development of novel, high-yielding conjugation chemistry for creating direct payload disulfide connections to any of several Cys mutation sites in THIOMAB antibodies or to Cys sites in other biomolecules (e.g., human serum albumin and cell-penetrating peptides). We conclude by demonstrating that hindered direct disulfide TDCs with two methyl groups adjacent to the disulfide, which have heretofore not been described for any bioconjugate, are more stable and more efficacious in mouse tumor xenograft studies than less hindered analogs.


Subject(s)
Cysteine , Disulfides/chemistry , Immunoconjugates/chemistry , Peptides/chemistry , Protein Engineering , Animals , Cell Line, Tumor , Cell Transformation, Neoplastic , Humans , Immunoconjugates/genetics , Mice
9.
Zhongguo Dang Dai Er Ke Za Zhi ; 18(12): 1291-1295, 2016 Dec.
Article in Zh | MEDLINE | ID: mdl-27974125

ABSTRACT

OBJECTIVE: To investigate the clinical features of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) in children. METHODS: The clinical data of 8 children with MERS were retrospectively analyzed. RESULTS: The mean age of onset was 5 years and 2 months (range 10 months to 12 years). The major clinical features included a history of prodromal infection, and among these children, 5 had pyrexia and 4 had vomiting. Of all the children, 6 were manifested as convulsion and 3 each were manifested as disturbance of consciousness and paroxysmal paropsia. Cranial diffusion-weighted magnetic resonance imaging (MRI) showed high signals in the splenium of the corpus callosum. Among these children, one child had symmetric and multiple long T1 and long T2 signals in the bilateral centrum semiovale and part of the temporal white matter. MRI reexamination performed after 5-30 days showed the disappearance of abnormal signals in all the children. The children were followed up for 3 months to 2 years, and no child experienced abnormal neurodevelopment. CONCLUSIONS: The development of MERS in children is closely associated with infection. MERS is characterized by high signals in the splenium of the corpus callosum on cranial diffusion-weighted MRI. Most children have good prognosis.


Subject(s)
Brain Diseases/pathology , Corpus Callosum/pathology , Encephalitis/pathology , Magnetic Resonance Imaging/methods , Child , Child, Preschool , Female , Humans , Infant , Male , Retrospective Studies
10.
Bioorg Med Chem Lett ; 25(4): 864-8, 2015 Feb 15.
Article in English | MEDLINE | ID: mdl-25613677

ABSTRACT

The cryptophycins are a potent class of cytotoxic agents that were evaluated as antibody drug conjugate (ADC) payloads. Free cryptophycin analog 1 displayed cell activity an order of magnitude more potent than approved ADC payloads MMAE and DM1. This potency increase was also reflected in the activity of the cryptophycin ADCs, attached via a either cleavable or non-cleavable linker.


Subject(s)
Antineoplastic Agents/therapeutic use , Depsipeptides/therapeutic use , Immunoconjugates/therapeutic use , Cell Line, Tumor , Humans
11.
J Imaging ; 10(4)2024 Mar 24.
Article in English | MEDLINE | ID: mdl-38667972

ABSTRACT

Direct sunlight in complex environmental conditions severely interferes with the light intensity response for imaging Polarization Sensor (PS), leading to a reduction in polarization orientation accuracy. Addressing this issue, this article analyzes the impact mechanism of direct sunlight on polarization sensor detection in a complex environment. The direct sunlight interference factor is introduced into the intensity response model of imaging polarization detection, enhancing the accuracy of the polarization detection model. Furthermore, a polarization state information analytical solution model based on direct sunlight compensation is constructed to improve the accuracy and real-time performance of the polarization state information solution. On this basis, an improved bio-orientation method based on direct sunlight compensation for imaging polarization sensor is proposed. The outdoor dynamic reorientation experiment platform is established to validate the effectiveness of the proposed method. Compared with the traditional methods, the experimental results demonstrate a 23% to 47% improvement in the polarization orientation accuracy under various solar zenith angles.

12.
J Affect Disord ; 347: 134-143, 2024 02 15.
Article in English | MEDLINE | ID: mdl-37995924

ABSTRACT

OBJECTIVES: To assess the contemporary prevalence and decade-long trends of sleep duration, sleep disorders and trouble sleeping among adults in the United States, as well as their risk factors, from 2005 to 2018. MATERIALS AND METHODS: We used National Health and Nutrition Examination Survey data to calculate the sleep duration and weighted prevalence of sleep disorders and trouble sleeping in adults aged 20 years or older. Sleep duration, sleep disorders and trouble sleeping were assessed by questionnaire. RESULTS: A total of 27,399 people were included in the survey on sleep duration, with a weighted percentage of normal sleep (7-8 h/night) of 56.33 % (95 % CI, 53.06-59.60 %) and a weighted percentage of short sleep (5-6 h/night) of 31.73 %. In stratified descriptions, participants aged 40-49 years were more likely to sleep less than five hours, while women aged 80 years and older were more likely to sleep longer and blacks were more likely to sleep shorter. A total of 27,406 participants were included in the survey for sleep disorders. The weighted proportion of the population with sleep disorders was 8.44 % (95 % CI, 7.79-9.8 %). Independent risk factors for sleep disorders were being 40-69 years old, being white, having a high education level, smoking, having hypertension, diabetes, heart disease, and BMI ≥ 25. From 2005 to 2014, the prevalence of sleep disorders increased year by year, from 7.44 % in 2005-2006 to 10.40 % in 2013-2014 (P for Trend<0.001). A total of 38,165 participants were included in the survey on trouble sleeping. The weighted proportion of the population with troubled sleeping was 27.30 % (25.70-28.90 %). Independent risk factors for troubled sleeping were being 30-79 years old, being white, having a high education level, smoking, drinking, having hypertension, diabetes, heart disease and BMI ≥ 25. From 2005 to 2018, the prevalence of trouble sleeping increased annually, from 24.44 % in 2005-2006 to 30.58 % in 2017-2018 (P for trend<0.001). CONCLUSION: Adults in the United States are likely to have abnormal sleep durations, and the prevalence of sleep disorders and troubled sleeping is on the rise.


Subject(s)
Diabetes Mellitus , Heart Diseases , Hypertension , Sleep Wake Disorders , Adult , Humans , Female , United States/epidemiology , Middle Aged , Aged , Nutrition Surveys , Sleep , Diabetes Mellitus/epidemiology , Hypertension/epidemiology , Sleep Wake Disorders/epidemiology
13.
Nat Commun ; 15(1): 466, 2024 Jan 11.
Article in English | MEDLINE | ID: mdl-38212321

ABSTRACT

Approved antibody-drug conjugates (ADCs) for HER2-positive breast cancer include trastuzumab emtansine and trastuzumab deruxtecan. To develop a differentiated HER2 ADC, we chose an antibody that does not compete with trastuzumab or pertuzumab for binding, conjugated to a reduced potency PBD (pyrrolobenzodiazepine) dimer payload. PBDs are potent cytotoxic agents that alkylate and cross-link DNA. In our study, the PBD dimer is modified to alkylate, but not cross-link DNA. This HER2 ADC, DHES0815A, demonstrates in vivo efficacy in models of HER2-positive and HER2-low cancers and is well-tolerated in cynomolgus monkey safety studies. Mechanisms of action include induction of DNA damage and apoptosis, activity in non-dividing cells, and bystander activity. A dose-escalation study (ClinicalTrials.gov: NCT03451162) in patients with HER2-positive metastatic breast cancer, with the primary objective of evaluating the safety and tolerability of DHES0815A and secondary objectives of characterizing the pharmacokinetics, objective response rate, duration of response, and formation of anti-DHES0815A antibodies, is reported herein. Despite early signs of anti-tumor activity, patients at higher doses develop persistent, non-resolvable dermal, ocular, and pulmonary toxicities, which led to early termination of the phase 1 trial.


Subject(s)
Antibodies, Monoclonal, Humanized , Antineoplastic Agents , Benzodiazepines , Breast Neoplasms , Immunoconjugates , Humans , Animals , Female , Breast Neoplasms/genetics , Macaca fascicularis/genetics , Receptor, ErbB-2/metabolism , Trastuzumab/therapeutic use , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Immunoconjugates/pharmacology , Immunoconjugates/therapeutic use , DNA
14.
Rev Sci Instrum ; 94(9)2023 Sep 01.
Article in English | MEDLINE | ID: mdl-37712777

ABSTRACT

Displacement measurement is of great significance to monitor the crack variation and ensure the health of building structures. Aiming at the problems of low sensitivity and high temperature error of fiber Bragg grating (FBG) displacement sensors in displacement monitoring, this paper presents an adjustable cantilever beam displacement sensor with the FBGs as the sensing element. The sensor adds double FBGs on the relative surfaces of the equal-strength cantilever beam, which increases the bending deformation on the FBG of the beam surface to improve the sensitivity and realize the temperature compensation of the sensor. By adding an adjustable external rod structure between a flexible spring and a fixed foot stand, the sensor can regulate the range of initial crack width for different occasions. A theoretical analysis of the displacement sensor is performed, and the simulation analysis and optimization design for the structural parameters of the cantilever beam elastic sensitive element are implemented by adopting SolidWorks and ANSYS software. Finally, a displacement testing platform is constructed to test its performance. Experimental results show that this design has a high sensitivity coefficient of 39.47 pm/mm and a temperature coefficient of 1.04 pm/°C in the range of initial crack width from 0 to 110 mm or from 0 to 130 mm depending on different monitoring situations. Furthermore, good linearity, hysteresis delay, repeatability, and temperature compensation performance have also been demonstrated.

15.
ACS Nano ; 16(8): 12991-13001, 2022 08 23.
Article in English | MEDLINE | ID: mdl-35969155

ABSTRACT

Inducing apoptosis in cancer cells is considered a potential therapeutic mechanism underlying cancers. Here, chiral folic acid (FA) conjugated Cys-CdTe/CdS quantum dots (QDs) conjugated with a cancer-targeting ligand were fabricated to induce apoptosis in vivo. Ligand-induced chirality mechanism for FA-Cys-CdTe/CdS QDs was discussed, which is verified by density functional theory (DFT) simulation. Interestingly, we found that the circular dichroism (CD) signals of chiral QDs can effectively distinguish breast cancer cells from normal cells, where a sharp decrease in CD signal and absorption intensity can be seen. Notably, chiral FA-Cys-CdTe/CdS QDs showed significant apoptosis-inducing ability after the release of mitochondrial apoptotic factors. Furthermore, in vivo experiments showed that chiral FA-Cys-CdTe/CdS QDs provide an efficient cancer ablation through the apoptosis process with negligible toxicity, demonstrating their great potential utility in targeted anticancer agent for future clinic application.


Subject(s)
Cadmium Compounds , Neoplasms , Quantum Dots , Tellurium , Folic Acid , Ligands
16.
Chem Sci ; 13(11): 3147-3160, 2022 Mar 16.
Article in English | MEDLINE | ID: mdl-35414872

ABSTRACT

The antibody-drug conjugate (ADC) is a well-validated modality for the cell-specific delivery of small molecules with impact expanding rapidly beyond their originally-intended purpose of treating cancer. However, antibody-mediated delivery (AMD) remains inefficient, limiting its applicability to targeting highly potent payloads to cells with high antigen expression. Maximizing the number of payloads delivered per antibody is one key way in which delivery efficiency can be improved, although this has been challenging to carry out; with few exceptions, increasing the drug-to-antibody ratio (DAR) above ∼4 typically destroys the biophysical properties and in vivo efficacy for ADCs. Herein, we describe the development of a novel bioconjugation platform combining cysteine-engineered (THIOMAB) antibodies and recombinant XTEN polypeptides for the unprecedented generation of homogeneous, stable "TXCs" with DAR of up to 18. Across three different bioactive payloads, we demonstrated improved AMD to tumors and Staphylococcus aureus bacteria for high-DAR TXCs relative to conventional low-DAR ADCs.

17.
Breast Cancer Res Treat ; 128(2): 347-56, 2011 Jul.
Article in English | MEDLINE | ID: mdl-20730488

ABSTRACT

Trastuzumab (Herceptin(®)) is currently used as a treatment for patients whose breast tumors overexpress HER2/ErbB2. Trastuzumab-DM1 (T-DM1, trastuzumab emtansine) is designed to combine the clinical benefits of trastuzumab with a potent microtubule-disrupting drug, DM1 (a maytansine derivative). Currently T-DM1 is being tested in multiple clinical trials. The mechanisms of action for trastuzumab include inhibition of PI3K/AKT signaling pathway, inhibition of HER-2 shedding and Fcγ receptor mediated engagement of immune cells, which may result in antibody-dependent cellular cytotoxicity (ADCC). Here we report that T-DM1 retains the mechanisms of action of unconjugated trastuzumab and is active against lapatinib resistant cell lines and tumors.


Subject(s)
Antibodies, Monoclonal/therapeutic use , Breast Neoplasms/drug therapy , Drug Resistance, Neoplasm/drug effects , Immunotoxins/therapeutic use , Maytansine/analogs & derivatives , Quinazolines/adverse effects , Receptor, ErbB-2/antagonists & inhibitors , Ado-Trastuzumab Emtansine , Animals , Antibodies, Monoclonal, Humanized , Antibody-Dependent Cell Cytotoxicity/drug effects , Blotting, Western , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cell Line, Tumor , Cell Survival/drug effects , Female , Humans , Immunoconjugates , Lapatinib , Maytansine/therapeutic use , Mice , Mice, Nude , Mice, Transgenic , Phosphatidylinositol 3-Kinases/metabolism , Receptor, ErbB-2/immunology , Receptor, ErbB-2/metabolism , Signal Transduction/drug effects , Trastuzumab
18.
ACS Nano ; 14(4): 4196-4205, 2020 04 28.
Article in English | MEDLINE | ID: mdl-32298573

ABSTRACT

Ligand-induced chirality in semiconducting nanocrystals has been the subject of extensive study in the past few years and shows potential applications in optics and biology. Yet, the origin of the chiroptical effect in semiconductor nanoparticles is still not fully understood. Here, we examine the effect of the interaction with amino acids on both the fluorescence and the optical activity of chiral semiconductor quantum dots (QDs). A significant fluorescence enhancement is observed for l/d-Cys-CdTe QDs upon interaction with all the tested amino acids, indicating suppression of nonradiative pathways as well as the passivation of surface trap sites brought via the interaction of the amino group with the CdTe QDs' surface. Heterochiral amino acids are shown to weaken the circular dichroism (CD) signal, which may be attributed to a different binding configuration of cysteine molecules on the QDs' surface. Furthermore, a red shift of both CD and fluorescence signals in l/d-Cys-CdTe QDs is only observed upon adding cysteine, while other tested amino acids do not exhibit such an effect. We speculate that the thiol group induces orbital hybridization of the highest occupied molecular orbital (HOMOs) of cysteine and the valence band of CdTe QDs, leading to the decrease of the energy band gap and a concomitant red shift of CD and fluorescence spectra. This is further verified by density functional theory calculations. Both the experimental and theoretical findings indicate that the addition of ligands that do not "directly" interact with the valence band (VB) of the QD (noncysteine moieties) changes the QD photophysical properties, as it probably modifies the way cysteine is bound to the surface. Hence, we conclude that it is not only the chemistry of the amino acid ligand that affects both CD and PL but also the exact geometry of binding that modifies these properties. Understanding the relationship between the QD's surface and chiral amino acid thus provides an additional perspective on the fundamental origin of induced chiroptical effects in semiconductor nanoparticles, potentially enabling us to optimize the design of chiral semiconductor QDs for chiroptic applications.


Subject(s)
Cadmium Compounds , Quantum Dots , Amino Acids , Optical Rotation , Tellurium
19.
J Med Chem ; 63(17): 9603-9622, 2020 09 10.
Article in English | MEDLINE | ID: mdl-32787101

ABSTRACT

Cytotoxic pyrrolobenzodiazepine (PBD)-dimer molecules are frequently utilized as payloads for antibody-drug conjugates (ADCs), and many examples are currently in clinical development. In order to further explore this ADC payload class, the physicochemical properties of various PBD-dimer molecules were modified by the systematic introduction of acidic and basic moieties into their chemical structures. The impact of these changes on DNA binding, cell membrane permeability, and in vitro antiproliferation potency was, respectively, determined using a DNA alkylation assay, PAMPA assessments, and cell-based cytotoxicity measurements conducted with a variety of cancer lines. The modified PBD-dimer compounds were subsequently incorporated into CD22-targeting ADCs, and these entities were profiled in a variety of in vitro and in vivo experiments. The introduction of a strongly basic moiety into the PBD-dimer scaffold afforded a conjugate with dramatically worsened mouse tolerability properties relative to ADCs derived from related payloads, which lacked the basic group.


Subject(s)
Benzodiazepines/chemistry , Dimerization , Immunoconjugates/adverse effects , Immunoconjugates/chemistry , Pyrroles/chemistry , Safety , Binding Sites , Cell Line, Tumor , Cell Proliferation/drug effects , Chemical Phenomena , DNA/chemistry , DNA/metabolism , Humans , Immunoconjugates/metabolism , Immunoconjugates/pharmacology , Models, Molecular , Nucleic Acid Conformation
20.
Mol Cancer Ther ; 17(7): 1441-1453, 2018 07.
Article in English | MEDLINE | ID: mdl-29695635

ABSTRACT

The receptor tyrosine kinase HER2 is overexpressed in approximately 20% of breast cancer, and its amplification is associated with reduced survival. Trastuzumab emtansine (Kadcyla, T-DM1), an antibody-drug conjugate that is comprised of trastuzumab covalently linked to the antimitotic agent DM1 through a stable linker, was designed to selectively deliver DM1 to HER2-overexpressing tumor cells. T-DM1 is approved for the treatment of patients with HER2-positive metastatic breast cancer following progression on trastuzumab and a taxane. Despite the improvement in clinical outcome, many patients who initially respond to T-DM1 treatment eventually develop progressive disease. The mechanisms that contribute to T-DM1 resistance are not fully understood. To this end, we developed T-DM1-resistant in vitro models to examine the mechanisms of acquired T-DM1 resistance. We demonstrate that decreased HER2 and upregulation of MDR1 contribute to T-DM1 resistance in KPL-4 T-DM1-resistant cells. In contrast, both loss of SLC46A3 and PTEN deficiency play a role in conferring resistance in BT-474M1 T-DM1-resistant cells. Our data suggest that these two cell lines acquire resistance through distinct mechanisms. Furthermore, we show that the KPL-4 T-DM1 resistance can be overcome by treatment with an inhibitor of MDR1, whereas a PI3K inhibitor can rescue PTEN loss-induced resistance in T-DM1-resistant BT-474M1 cells. Our results provide a rationale for developing therapeutic strategies to enhance T-DM1 clinical efficacy by combining T-DM1 and other inhibitors that target signaling transduction or resistance pathways. Mol Cancer Ther; 17(7); 1441-53. ©2018 AACR.


Subject(s)
Breast Neoplasms/drug therapy , Receptor, ErbB-2/genetics , Trastuzumab/pharmacology , ATP Binding Cassette Transporter, Subfamily B/genetics , Animals , Breast Neoplasms/genetics , Breast Neoplasms/pathology , Bridged-Ring Compounds/pharmacology , Cell Line, Tumor , Drug Resistance, Neoplasm/drug effects , Female , Gene Expression Regulation, Neoplastic/drug effects , Humans , Immunoconjugates/pharmacology , Mice , PTEN Phosphohydrolase/genetics , Phosphatidylinositol 3-Kinases/genetics , Signal Transduction/drug effects , Taxoids/pharmacology , Xenograft Model Antitumor Assays
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