Effective cancer therapy based on selective drug delivery into cells across their membrane using receptor-mediated endocytosis

Cancer is one of the major causes of death globally. The current treatment options are insufficient, leading to unmet medical needs in cancer treatment. Off-target side effects, multidrug resistance, selective distribution to cancerous tissues, and cell membrane permeation of anti-cancer agents are critical problems to overcome. There is a method to solve these problems by using receptor-mediated endocytosis (RME). It is well known that proteins such as integrin, HER2, EGFR, or other cancer biomarkers are specifically overexpressed on the surface of target cancer cells. By taking advantage of such specific receptors, payloads can be transported into cells through endocytosis using a conjugate composed of the corresponding ligands connected to the payloads by an appropriate linker. After RME, the payloads released by endosomal escape into the cytoplasm can exhibit the cytotoxic activity against cancer cells. Cell-penetrating peptides (CPPs), tumor-homing peptides (THPs), and monoclonal antibodies (mAbs) are utilized as ligands in this system. Antibody drug conjugates (ADCs) based on RME have already been used to cure cancer. In addition to the canonical conjugate method, nanocarriers for spontaneous accumulation in cancer tissue due to enhanced permeability and retention (EPR) effect are extensively used. In this review, I introduce the possibilities and advantages of drug design and development based on RME for the treatment of cancer.     

Carrier Transport and Recombination in Efficient “All‐Small‐Molecule” Solar Cells with the Nonfullerene Acceptor IDTBR

Reaching device efficiencies that can rival those of polymer‐fullerene Bulk Heterojunction (BHJ) solar cells (>10%) remains challenging with the “All‐Small‐Molecule” (All‐SM) approach, in part because of (i) the morphological limitations that prevail in the absence of polymer and (ii) the difficulty to raise and balance out carrier mobilities across the active layer. In this report, the authors show that blends of the SM donor DR3TBDTT (DR3) and the nonfullerene SM acceptor O‐IDTBR are conducive to “All‐SM” BHJ solar cells with high open‐circuit voltages (V_OC) >1.1 V and PCEs as high as 6.4% (avg. 6.1%) when the active layers are subjected to a post‐processing solvent vapor‐annealing (SVA) step with dimethyl disulfide (DMDS). Combining electron energy loss spectroscopy (EELS) analyses and systematic carrier recombination examinations, the authors show that SVA treatments with DMDS play a determining role in improving charge transport and reducing non‐geminate recombination for the DR3:O‐IDTBR system. Correlating the experimental results and device simulations, it is found that substantially higher BHJ solar cell efficiencies of >12% can be achieved if the IQE and carrier mobilities of the active layer are increased to >85% and >10^?4 cm² V^?1 s^?1, respectively, while suppressing the recombination rate constant k to <10^?12 cm³ s^?1.     

A New Perspective on the Role of A‐Site Cations in Perovskite Solar Cells

As the race toward higher efficiency for inorganic/organic hybrid perovskite solar cells (PSCs) is becoming highly competitive, a design scheme to maximize carrier transport toward higher power efficiency has been urgently demanded. In this study, a hidden role of A‐site cations of PSCs in carrier transport, which has been largely neglected is unraveled, i.e., tuning the Fröhlich electron–phonon (e–ph) coupling of longitudinal optical (LO) phonon by A‐site cations. The key for steering Fröhlich polaron is to control the interaction strength and the number of proton (or lithium) coordination to halide ions. The coordination to I^? alleviates electron–phonon scattering by either decreasing the Born effective charge or absorbing the LO motion of I. This novel principle discloses low electron–phonon coupling in several promising organic cations including hydroxyl–ammonium cation (NH₃OH⁺), hydrazinium cation (NH₃NH₂⁺) and possibly Li⁺ solvating methylamine (Li⁺???NH₂CH₃), on a par with methyl–ammonium cations. A new perspective on the role of A‐site cations could help in improving power efficiency and accelerating the application of PSCs.     

Molecular structure influence in the recognition of phthaleins by the electrogenic organic anion carrier at the sinusoidal plasma membrane level in the liver

The hepatocytic uptake of cholephilic organic anions occurs by carrier-mediated mechanisms. Electrogenic and electroneutral transport systems have been described. The aim of this study was to determine the dissociation constant (Kd) of the Electrogenic Carrier System(s) (ECS) for tetrabromosulfophthalein (BSP), dibromosulfophthalein (DBSP), tetrabromophthalein (TBP), tetrabromosulfonephthalein (TBS) and thymol blue (TB). Kd (uM) values for ECS-organic anion complexes were: ECS-BSP = 3.61 ± 0.18; ECS-DBSP = 11.61 ± 1.32; ECS-TBP = 0.51 ± 0.08; ECS-TBS = 1.31 ± 0.25; ECS-TB = 9.44 ± 1.80.From these data, it is possible to conclude that molecular characteristics of the organic anions are important factors in determining the dissociation constant for the electrogenic hepatic carrier(s). In this sense, the addition of two sulphonic groups on the phenolic ring; the presence of a sulphonic on the benzenic ring and the absence of two or four bromines on the molecule confers a lower affinity for ECS.     

Structure of a putative ClpS N‐end rule adaptor protein from the malaria pathogen Plasmodium falciparum

The N‐end rule pathway uses an evolutionarily conserved mechanism in bacteria and eukaryotes that marks proteins for degradation by ATP‐dependent chaperones and proteases such as the Clp chaperones and proteases. Specific N‐terminal amino acids (N‐degrons) are sufficient to target substrates for degradation. In bacteria, the ClpS adaptor binds and delivers N‐end rule substrates for their degradation upon association with the ClpA/P chaperone/protease. Here, we report the first crystal structure, solved at 2.7 Å resolution, of a eukaryotic homolog of bacterial ClpS from the malaria apicomplexan parasite Plasmodium falciparum (Pfal). Despite limited sequence identity, Plasmodium ClpS is very similar to bacterial ClpS. Akin to its bacterial orthologs, plasmodial ClpS harbors a preformed hydrophobic pocket whose geometry and chemical properties are compatible with the binding of N‐degrons. However, while the N‐degron binding pocket in bacterial ClpS structures is open and accessible, the corresponding pocket in Plasmodium ClpS is occluded by a conserved surface loop that acts as a latch. Despite the closed conformation observed in the crystal, we show that, in solution, Pfal‐ClpS binds and discriminates peptides mimicking bona fide N‐end rule substrates. The presence of an apicoplast targeting peptide suggests that Pfal‐ClpS localizes to this plastid‐like organelle characteristic of all Apicomplexa and hosting most of its Clp machinery. By analogy with the related ClpS1 from plant chloroplasts and cyanobacteria, Plasmodium ClpS likely functions in association with ClpC in the apicoplast. Our findings open new venues for the design of novel anti‐malarial drugs aimed at disrupting parasite‐specific protein quality control pathways.     

Intranasal immunization with a peptide conjugated to Salmonella flagellin induces both systemic and mucosal peptide‐specific antibody responses in mice

In this study, the mucosal adjuvant activity of Salmonella flagellin as a carrier in a conjugate of EXP153–rFliC was investigated. EXP153–rFliC was made by conjugation of a synthetic B‐cell epitope peptide derived from Plasmodium falciparum exported protein‐1(EXP153) to recombinant phase 1 flagellin of Salmonella enterica serovar Typhimurium expressed in Escherichia coli (rFliC), and used to immunize BALB/c mice via intranasal instillation. It was found that robust EXP153‐specific serum IgG antibodies were induced without additional adjuvant. EXP153‐specific sIgA antibodies were also induced, these being detected in bronchoalveolar, nasal, vaginal and intestinal washes. These observations demonstrate that Salmonella flagellin as a carrier is an effective mucosal adjuvant in that its conjugated peptide induces antibody responses.