Effects of substrate stiffness on the viscoelasticity and migration of prostate cancer cells examined by atomic force microscopy

• Xiaoqiong Tang,
• Yan Zhang,
• Jiangbing Mao,
• Yuhua Wang,
• Zhenghong Zhang,
• Zhengchao Wang and
• Hongqin Yang

Beilstein J. Nanotechnol. 2022, 13, 560–569, doi:10.3762/bjnano.13.47

• study may provide a new approach to investigate the migration mechanism of PCa cells in addition to cytoskeleton-mediated migration of PCa cells, which can be useful for cancer therapeutic drug screening and development. Experimental Cell culture PZ-HPV-7 normal human prostate epithelial cells and PC-3

Detection and imaging of Hg(II) in vivo using glutathione-functionalized gold nanoparticles

• Gufeng Li,
• Shaoqing Li,
• Rui Wang,
• Min Yang,
• Lizhu Zhang,
• Yanli Zhang,
• Wenrong Yang and
• Hongbin Wang

Beilstein J. Nanotechnol. 2022, 13, 549–559, doi:10.3762/bjnano.13.46

• the fluorescent “ON” form. Keywords: cell imaging; fluorescence probes; glutathione; gold nanoparticles; mercury ions; rhodamine 6G derivatives; Introduction Metal nanoparticles have been widely used in the development and construction of sensor systems and drug carriers due to their excellent

• biocompatibility, large specific surface area, and remarkable photoelectric properties [1][2][3]. Among them, gold nanoparticles (GNPs) have been frequently employed for drug delivery, sensing, imaging, and photodynamic therapy owing to their high extinction coefficient, distinct optical properties, excellent

• conjugate with drug molecules and fluorescent dyes [24]. Recently, we developed a novel Cu(II)-triggered release system with gold nanoparticles surface-modified with ʟ-cysteine for molecular delivery and imaging in cells [31]. Well dispersed GNP–ʟ-cysteine was conjugated with Rh6G2 (GNP–ʟ-Cys–Rh6G2) for a

Ciprofloxacin-loaded dissolving polymeric microneedles as a potential therapeutic for the treatment of S. aureus skin infections

• Sharif Abdelghany,
• Walhan Alshaer,
• Yazan Al Thaher,
• Maram Al Fawares,
• Amal G. Al-Bakri,
• Saja Zuriekat and
• Randa SH. Mansour

Beilstein J. Nanotechnol. 2022, 13, 517–527, doi:10.3762/bjnano.13.43

• results suggest that CIP_MN1 can be a potential delivery system for the treatment of S. aureus skin infections. Keywords: dissolving microneedles; microneedles; polyvinyl alcohol (PVA); polyvinylpyrrolidone (PVP); skin infection; Introduction Topical and transdermal drug delivery is a major route for

• the administration of antimicrobials to the infected parts of the skin and to the systemic circulation. The main limitation to dermal drug delivery is skin barriers. This is mainly due the uppermost dead keratinized skin layer known as the stratum corneum [1]. Microneedles of different shapes and

• sizes have been utilized to overcome this limitation since they can painlessly penetrate the upper skin layers [2]. Patients can self-administer microneedles and, thus, overcome the pain associated with conventional parenteral injections. Moreover, this drug delivery system can potentially overcome the

Design and characterization of polymeric microneedles containing extracts of Brazilian green propolis

• Camila Felix Vecchi,
• Rafaela Said dos Santos,
• Jéssica Bassi da Silva and
• Marcos Luciano Bruschi

Beilstein J. Nanotechnol. 2022, 13, 503–516, doi:10.3762/bjnano.13.42

• Camila Felix Vecchi Rafaela Said dos Santos Jessica Bassi da Silva Marcos Luciano Bruschi Laboratory of Research and Development of Drug Delivery Systems, Postgraduate Program in Pharmaceutical Sciences, Department of Pharmacy, State University of Maringa, Maringa, Brazil 10.3762/bjnano.13.42

• permeation mechanism [6][9][10]. Nanocarriers can be used together with polymeric MNs in a synergistic therapy. The nanocarriers can immediately come into contact with the stratum corneum with the help of polymeric MNs, enhancing the transdermal drug delivery of the drugs. Furthermore, these polymeric MNs

• can encapsulate several types of nanocarriers, making it a unique system with different activities [11]. Solid MNs are used for pre-treatment of the skin. They serve only to create micropores, increasing permeability and facilitating the administration of the drug. The drug will be inserted over the

Ethosomal (−)-epigallocatechin-3-gallate as a novel approach to enhance antioxidant, anti-collagenase and anti-elastase effects

• Çiğdem Yücel,
• Gökçe Şeker Karatoprak,
• Sena Yalçıntaş and
• Tuğba Eren Böncü

Beilstein J. Nanotechnol. 2022, 13, 491–502, doi:10.3762/bjnano.13.41

• Cigdem Yucel Gokce Seker Karatoprak Sena Yalcintas Tugba Eren Boncu Faculty of Pharmacy, Department of Pharmaceutical Technology, Erciyes University, 38280 Kayseri, Turkey Faculty of Pharmacy, Department of Pharmacognosy, Erciyes University, 38280 Kayseri, Turkey Erciyes University, Ziya Eren Drug

• neurodegenerative disorders [7][8][9]. However, there are some difficulties in the formulation of EGCG such as the first pass metabolism effect, enzymatic degradation, and low bioavailability [8][10]. Skin delivery, besides being painless and noninvasive, has many advantages such as controlled drug delivery

• , reduced dose frequency, avoidance of first pass metabolism by the liver, and it can be self-administered. It includes the concept of topical drug delivery aimed at treating a local dermatological disorder without the need to target the systemic circulation by using transdermal drug delivery for systemic

Zinc oxide nanostructures for fluorescence and Raman signal enhancement: a review

• Ioana Marica,
• Fran Nekvapil,
• Maria Ștefan,
• Cosmin Farcău and
• Alexandra Falamaș

Beilstein J. Nanotechnol. 2022, 13, 472–490, doi:10.3762/bjnano.13.40

• diagnosis, therapeutic monitoring, and drug discovery [51]. Several examples of fluorescence enhancement using ZnO nanostructures are given in Table 1. Fewer studies investigated the enhancement of fluorescence in ZnO–metal nanocomposites and further research is still needed to explore this direction. Core

Micro- and nanotechnology in biomedical engineering for cartilage tissue regeneration in osteoarthritis

• Zahra Nabizadeh,
• Mahmoud Nasrollahzadeh,
• Hamed Daemi,
• Mohamadreza Baghaban Eslaminejad,
• Ali Akbar Shabani,
• Mehdi Dadashpour,
• Majid Mirmohammadkhani and
• Davood Nasrabadi

Beilstein J. Nanotechnol. 2022, 13, 363–389, doi:10.3762/bjnano.13.31

• engineering cartilage tissue structures. 3.1.1 Application of microspheres in chondrogenic differentiation. Microspheres are used in drug delivery systems because of their spatiotemporally controlled release capabilities (see Table 2 below). They are small spherical particles from organic or inorganic

• 19 days [28]. In another study, researchers developed PLGA-based microspheres to control the release of rapamycin in the joint [29]. The microspheres provided sustained and controlled release of rapamycin for several weeks, retained drug potency, and prevented OA-like changes in chondrocytes cultured

• biomimetic nanocomposites to imitate pseudostratified features of the ECM to develop bioinspired scaffolds [47][48][49]. 3.1.2.1 Nanoparticles (NPs). In recent years, NPs have been increasingly used in regenerative medicine (Table 1) and other medical areas. NPs have been successfully developed for drug

Systematic studies into uniform synthetic protein nanoparticles

• Nahal Habibi,
• Ava Mauser,
• Jeffery E. Raymond and
• Joerg Lahann

Beilstein J. Nanotechnol. 2022, 13, 274–283, doi:10.3762/bjnano.13.22

• , 48109, USA 10.3762/bjnano.13.22 Abstract Nanoparticles are frequently pursued as drug delivery carriers due to their potential to alter the pharmacological profiles of drugs, but their broader utility in nanomedicine hinges upon exquisite control of critical nanoparticle properties, such as shape, size

• SPNPs made from blended proteins can serve as a promising drug delivery carrier owing to the ease of production, the composition versatility, and the control over their size, shape and dispersity. Keywords: nanogels; nanomedicine; particle characterization; protein-based biomaterials; Introduction As

• nanoparticle platforms for drug delivery transition from novelties to foundational biomedical technologies [1][2][3], it is critical to augment the existing strategies with precisely engineered nanocarriers that are better equipped to maneuver the host of barriers that exist in clinical translation [4][5

Photothermal ablation of murine melanomas by Fe₃O₄ nanoparticle clusters

• Xue Wang,
• Lili Xuan and
• Ying Pan

Beilstein J. Nanotechnol. 2022, 13, 255–264, doi:10.3762/bjnano.13.20

• nanomaterial that has received considerable attention is Fe3O4 core-based nanoparticles, which have been approved by the Food and Drug Administration (FDA) as safe biomaterial with no long-term toxicity [6][7]. The superparamagnetic properties make them ideally suited for many biomedical applications, such as

• MRI imaging, targeted drug delivery and hyperthermia therapy [8][9]. Hyperthermia therapy can be achieved by using either magnetic fields or NIR irradiation. Application of an external alternating magnetic field on these nanoparticles leads to the production of heat to mediate magnetic hyperthermia

Effects of drug concentration and PLGA addition on the properties of electrospun ampicillin trihydrate-loaded PLA nanofibers

• Tuğba Eren Böncü and
• Nurten Ozdemir

Beilstein J. Nanotechnol. 2022, 13, 245–254, doi:10.3762/bjnano.13.19

• concentration (4–12%) and addition of PLGA (20–80%) on the spinnability of the solutions, morphology, average nanofiber diameter, encapsulation efficiency, drug release, and mechanical properties of PLA and PLA/PLGA nanofibers were examined. All nanofibers were bead-free and uniform. They had favorable

• encapsulation efficiency (approx. 90%) and mechanical properties. The increase in the amount of ampicillin trihydrate caused an increase in the diameter and burst effect of the nanofibers. The drug release ended on the 7th and 3rd day with nanofibers containing 4% and 12% of drug, respectively. The prolonged

• and controlled drug release for ten days was obtained with nanofibers containing 8% of drug. Thus, the ideal drug concentration was determined to be 8%. Nanofibers containing PLA/PLGA had a larger diameter than those including PLA. In addition, both the strength and elongation of nanofibers decreased

Engineered titania nanomaterials in advanced clinical applications

• Padmavati Sahare,
• Paulina Govea Alvarez,
• Juan Manual Sanchez Yanez,
• Gabriel Luna-Bárcenas,
• Samik Chakraborty,
• Sujay Paul and
• Miriam Estevez

Beilstein J. Nanotechnol. 2022, 13, 201–218, doi:10.3762/bjnano.13.15

• nanotubes , nanobelts, mesostructured, nanoflowers, including many more as displayed in the SEM image of Figure 1 [3]. Moreover, TiO2 has recently been approved for use in food and drug products by the American Food and Drug Administration (FDA) [4]. The first clinical application of nanoscale TiO2 was

• minimize the risk of device-related infections, implants are usually coated with TiO2 nanotubes, which under UV irradiation, generate reactive oxygen species (ROS), resulting in the disinfection ability [13]. One of the most vital contributions of nanotechnology is the development of novel modes of drug

• delivery. Ideal drug delivery systems encompass two elements, that is, the control over drug release and the ability to target specific locations in order to reduce systemic toxicity and undesirable side effects. Porous TiO2 has shown tremendous ability to sustain a concentration of drugs within the

Piezoelectric nanogenerator for bio-mechanical strain measurement

• Zafar Javed,
• Lybah Rafiq,
• Muhammad Anwaar Nazeer,
• Saqib Siddiqui,
• Muhammad Babar Ramzan,
• Muhammad Qamar Khan and
• Muhammad Salman Naeem

Beilstein J. Nanotechnol. 2022, 13, 192–200, doi:10.3762/bjnano.13.14

• , monofilaments, and powder. This material is trending in textile-based research where different researchers are working to manufacture smart textiles to generate energy [22][23]. Nanofibers have many technical applications such as in air and liquid filtration [24][25], tissue engineering [26][27], drug delivery

• developing artificial organs and blood vessels, and in gene and drug delivery [35]. Monitoring joint angles through wearable systems enables human posture and gesture to be reconstructed as a support for physical rehabilitation both in clinics and at the patients’ home [36]. To date, wearable sensors used

Bacterial safety study of the production process of hemoglobin-based oxygen carriers

• Axel Steffen,
• Yu Xiong,
• Radostina Georgieva,
• Ulrich Kalus and
• Hans Bäumler

Beilstein J. Nanotechnol. 2022, 13, 114–126, doi:10.3762/bjnano.13.8

• possible applications for these microparticles. For example, enzyme particles have been produced to be used as microreactors or biosensors [4]. This method can also represent a promising approach to the production of drug carriers by the precipitation of favorable biopolymers and corresponding surface

• modifications [5][6]. Thus, it was possible to immobilize vitamin B2 (riboflavin) in these particles together with human serum albumin (HSA). This resulted in a drug delivery system with good hemocompatibility and release of riboflavin over a prolonged period [7]. In addition, HSA microparticles could be loaded

• with doxorubicin, a cytostatic drug used in chemotherapy for cancer treatment. These particles showed higher efficacy in inhibiting metabolic activity in cell culture in comparison to free doxorubicin [8]. To be used as an artificial oxygen carrier, hemoglobin is isolated from bovine blood. Compared to

Theranostic potential of self-luminescent branched polyethyleneimine-coated superparamagnetic iron oxide nanoparticles

• Rouhollah Khodadust,
• Ozlem Unal and
• Havva Yagci Acar

Beilstein J. Nanotechnol. 2022, 13, 82–95, doi:10.3762/bjnano.13.6

• valuable since they are widely used for drug and gene delivery and may provide “label-free tracking” of these agents in vivo and in vitro [25][26]. Although both PEI and PAMAM have been studied for drug/gene delivery for decades, these systems have not been recognized as luminescent delivery vehicles until

• theranostic nanomaterials, PAMAM and PEI were frequently coupled with superparamagnetic iron oxide nanoparticles (SPIONs) for drug/gene delivery combined with magnetic resonance imaging [31][32]. Usually, these systems were conjugated with other fluorescent tags for optical detection of nanoparticles in cells

• , holds great potential for effective gene/drug delivery coupled with dual-mode imaging. a) TEM image of SPION@bPEI. b) AFM micrograph image of SPION@bPEI (magnetic mode). c) X-ray diffraction pattern of SPION@bPEI prepared via the in situ coating method. Since the presence of the polymer prevented the

Sputtering onto liquids: a critical review

• Anastasiya Sergievskaya,
• Adrien Chauvin and
• Stephanos Konstantinidis

Beilstein J. Nanotechnol. 2022, 13, 10–53, doi:10.3762/bjnano.13.2

Alteration of nanomechanical properties of pancreatic cancer cells through anticancer drug treatment revealed by atomic force microscopy

• Xiaoteng Liang,
• Shuai Liu,
• Xiuchao Wang,
• Dan Xia and
• Qiang Li

Beilstein J. Nanotechnol. 2021, 12, 1372–1379, doi:10.3762/bjnano.12.101

• aggressive cancer cell BxPC-3. In addition, the Young's modulus of MIA PaCa-2 rises with the increasing of DOX concentration. This study may provide a new strategy of detecting cancer, and evaluate the possible interaction of drugs on cells. Keywords: anticancer drug; atomic force microscopy; nanomechanical

• the physical properties of HeLa cells treated by docetaxel are different from that of untreated ones [9]. Therefore, the study of drug–cell interaction regarding cellular mechanics could be an effective way for drug evaluation. Important information, including drug efficacy and safety can be obtained

• ultrastructure of living cells [15][16], cell membranes, membrane proteins [17][18] and DNA [19], and through recording single molecular force spectra [20][21]. However, the morphology and the nanoscale mechanical properties of malignant pancreatic cancer cells (PCCs) under anticancer drug treatment have not

Biocompatibility and cytotoxicity in vitro of surface-functionalized drug-loaded spinel ferrite nanoparticles

• Sadaf Mushtaq,
• Khuram Shahzad,
• Tariq Saeed,
• Anwar Ul-Hamid,
• Bilal Haider Abbasi,
• Nafees Ahmad,
• Waqas Khalid,
• Muhammad Atif,
• Zulqurnain Ali and
• Rashda Abbasi

Beilstein J. Nanotechnol. 2021, 12, 1339–1364, doi:10.3762/bjnano.12.99

• (MFe2O4, where M = Fe, Co, Ni, or Zn) nanoparticles (NPs) were developed as carriers of the anticancer drugs doxorubicin (DOX) and methotrexate (MTX). Physical characterizations confirmed the formation of pure cubic structures (14–22 nm) with magnetic properties. Drug-loaded NPs exhibited tumor

• specificity with significantly higher (p < 0.005) drug release in an acidic environment (pH 5.5). The nanoparticles were highly colloidal (zeta potential = −35 to −26 mV) in deionized water, phosphate buffer saline (PBS), and sodium borate buffer (SBB). They showed elevated and dose-dependent cytotoxicity in

• vitro compared to free drug controls. The IC50 values ranged from 0.81 to 3.97 μg/mL for HepG2 and HT144 cells, whereas IC50 values for normal lymphocytes were 10 to 35 times higher (18.35–43.04 µg/mL). Cobalt ferrite (CFO) and zinc ferrite (ZFO) NPs were highly genotoxic (p < 0.05) in cancer cell lines

Identifying diverse metal oxide nanomaterials with lethal effects on embryonic zebrafish using machine learning

• Richard Liam Marchese Robinson,
• Haralambos Sarimveis,
• Philip Doganis,
• Xiaodong Jia,
• Marianna Kotzabasaki,
• Christiana Gousiadou,
• Stacey Lynn Harper and
• Terry Wilkins

Beilstein J. Nanotechnol. 2021, 12, 1297–1325, doi:10.3762/bjnano.12.97

• ; Introduction A variety of nanomaterial (NM)-enabled products have already been marketed [1][2] and there is considerable interest in the development of novel engineered nanomaterials (ENMs) for a variety of applications. Nanomedicine, including ENM-based therapeutic agents, nanocarriers (i.e., targeted drug

A review on slip boundary conditions at the nanoscale: recent development and applications

• Ruifei Wang,
• Jin Chai,
• Bobo Luo,
• Xiong Liu,
• Jianting Zhang,
• Min Wu,
• Mingdan Wei and
• Zhuanyue Ma

Beilstein J. Nanotechnol. 2021, 12, 1237–1251, doi:10.3762/bjnano.12.91

• related to nanotechnology, such as ion separation and drug discovery, should be investigated and developed. Schematic representation of the definition of slip lengths: (a) no-slip, (b) true slip length, (c) apparent slip length, and (d) effective slip length. Figures 1a–c were redrawn from [49] and Figure

Self-assembly of amino acids toward functional biomaterials

• Huan Ren,
• Lifang Wu,
• Lina Tan,
• Yanni Bao,
• Yuchen Ma,
• Yong Jin and
• Qianli Zou

Beilstein J. Nanotechnol. 2021, 12, 1140–1150, doi:10.3762/bjnano.12.85

• biomaterials; intermolecular interactions; self-assembly; Review Introduction Biomaterials play a crucial role in the treatment of diseases and health care and have been widely used in prostheses and drug delivery devices [1]. Clinical applications of biomaterials include the use of metals, ceramics, and

• in vivo [28] compared with the self-assembly of large molecules, such as proteins and peptides. Importantly, amino acids or amino acid derivatives may be self-assembled with other components to form functional architectures, such as drug delivery systems, light collection systems, and imaging systems

• acid and functional molecule self-assembly (drug, photosensitizer) (Figure 1). In this paper, the self-assembly of single amino acids is discussed first. We then discuss the co-assembly of amino acids and their derivatives with functional components including metal ions, photosensitizers (PS), and

pH-driven enhancement of anti-tubercular drug loading on iron oxide nanoparticles for drug delivery in macrophages

• Karishma Berta Cotta,
• Sarika Mehra and
• Rajdip Bandyopadhyaya

Beilstein J. Nanotechnol. 2021, 12, 1127–1139, doi:10.3762/bjnano.12.84

• deployment in drug delivery is contingent upon controlled drug loading and a desired release profile, with simultaneous biocompatibility and cellular targeting. Iron oxide nanoparticles (IONPs), being biocompatible, are used as drug carriers. However, to prevent aggregation of bare IONPs, they are coated

• the surrounding pH, drug loading enhancement could be pH dependent. Hence, upon synthesizing IONPs, they were coated with NOR, either at pH 5 (predominantly as cationic, NOR+) or at pH 10 (predominantly as anionic, NOR−). We observed that, drug loading at pH 5 exceeded that at pH 10 by 4.7–5.7 times

• . Furthermore, only the former (pH 5 system) exhibited a desirable slower drug release profile, compared to the free drug. NOR-coated IONPs also enable a 22 times higher drug accumulation in macrophages, compared to identical extracellular concentrations of the free drug. Thus, lowering the drug coating pH to 5

Use of nanosystems to improve the anticancer effects of curcumin

• Andrea M. Araya-Sibaja,
• Norma J. Salazar-López,
• Krissia Wilhelm Romero,
• José R. Vega-Baudrit,
• J. Abraham Domínguez-Avila,
• Carlos A. Velázquez Contreras,
• Ramón E. Robles-Zepeda,
• Mirtha Navarro-Hoyos and
• Gustavo A. González-Aguilar

Beilstein J. Nanotechnol. 2021, 12, 1047–1062, doi:10.3762/bjnano.12.78

• materials for nanomedical applications. Imaging-guided drug delivery of CUR-based nanosystems may also directly target specific cells, thereby increasing the therapeutic and chemopreventive efficacy of this versatile compound. Keywords: nanocarrier; nanoformulations; nanosized delivery systems; phenolic

• normal and abnormal cells [4], which leads to systemic toxicity that triggers hair loss, loss of appetite, immunosuppression, and inflammation [3]. These side effects can be severe enough to significantly impact the efficacy of a given treatment, while also causing high patient discomfort [5]. Low drug

• , since it avoids bioavailability issues. However, this results in increased toxicity and side effects [3]. Therefore, one of the goals of new and/or improved cancer therapies is for the drug to only target malignant cells in sufficient concentrations and with minimal distribution to other tissues to

An overview of microneedle applications, materials, and fabrication methods

• Zahra Faraji Rad,
• Philip D. Prewett and
• Graham J. Davies

Beilstein J. Nanotechnol. 2021, 12, 1034–1046, doi:10.3762/bjnano.12.77

• expand the scope for delivery of vaccines and therapeutic agents through the skin and withdrawing biofluids for point-of-care diagnostics – so-called theranostics. Unskilled and painless applications of microneedle patches for blood collection or drug delivery are two of the advantages of microneedle

• arrays over hypodermic needles. Developing the necessary microneedle fabrication processes has the potential to dramatically impact the health care delivery system by changing the landscape of fluid sampling and subcutaneous drug delivery. Microneedle designs which range from sub-micron to millimetre

• microneedle systems applications, designs, material selection, and manufacturing methods. Keywords: drug delivery; microelectromechanical systems (MEMS); microfabrication; microneedles; point-of-care diagnostics; Introduction The concept of microneedle structures to penetrate painlessly the outermost layer

The role of deep eutectic solvents and carrageenan in synthesizing biocompatible anisotropic metal nanoparticles

• Nabojit Das,
• Akash Kumar and
• Raja Gopal Rayavarapu

Beilstein J. Nanotechnol. 2021, 12, 924–938, doi:10.3762/bjnano.12.69

• variations and flexibility of tuning the size and shape of the metal nanoparticles at the nanoscale made them promising candidates for biomedical applications such as therapeutics, diagnostics, and drug delivery. However, safety and risk assessment of the nanomaterials for clinical purposes are yet to be

• , these nanomaterials are far away from a substantial use in biological applications due to toxic capping agents employed during synthesis. Several counterparts such as polymers, lipids, and chitosan-based nanoparticles are extensively explored in drug delivery and therapeutic applications due to their

• synthesis methods have been developed for environmental applications, such as biohydrogen production and chromium deionization [15][16][17][18]. In addition, polymer-based nanoparticles showed low drug loading and encapsulation efficiency. The acidic nature of poly(lactic-co-glycolic acid) is not suitable

The role of convolutional neural networks in scanning probe microscopy: a review

• Ido Azuri,
• Irit Rosenhek-Goldian,
• Neta Regev-Rudzki,
• Georg Fantner and
• Sidney R. Cohen

Beilstein J. Nanotechnol. 2021, 12, 878–901, doi:10.3762/bjnano.12.66

• learning and linear programming (an optimization method) for tracking single cells in live-cell imaging of both fluorescent and bright-field images of the cell cytoplasm [112]. Newby et al. developed a CNN for fully automated submicrometer-scale localization of particles such as viruses, proteins, and drug