Diagnosis and Treatment

E. Coli *Infections - Importance of Early Diagnosis and Efficient Treatment*

International Journal of Research in Pharmaceutical Sciences.

[36] Ningsih E, Padmadisastra T, Soedjanaatmadja UMS. Isolasi Pemurnian dan Karakterisasi Enzim beta-galaktosidase dari *Escherichia coli* B-130. Bandung: Laporan Tugas Akhir Penelitian. Universitas Padjadjaran;

2016;**8**(1):1-8

1994

Research in Pharmaceutical Sciences.

Wang Y, Yang S, et al. Co-expression of chaperones from *P. furiosus* enhanced the soluble expression of the recombinant hyperthermophilic α -amylase in *E. coli*. Cell Stress and Chaperones.

[30] Zhang H, Yuan Q, Zhu Y, Ma R. Expression and preparation of

recombinant hepcidin in *Escherichia coli*. Protein Expression and Purification.

[31] Lin H-H, Yin L-J, Jiang S-T. Cloning,

expression, and purification of *Pseudomonas aeruginosa* keratinase in *Escherichia coli* AD494 (DE3) pLysS expression system. Journal of Agricultural and Food Chemistry.

[32] Brüsehaber E, Schwiebs A, Schmidt M, Bottcher D, Bornscheuer UT. Production of pig liver esterase in batch fermentation of *E. coli*. Origami. Applied Microbiology and Biotechnology. 2010;**86**(5):

[33] Choi JH, Keum KC, Lee SY.

Production of recombinant proteins by high cell density culture of *Escherichia coli*. Chemical Engineering Science.

[34] Maksum IP. Sriwidodo, Indriyani A. Sistem Ekspresi Protein Rekombinan dalam *Eschercia coli* secara Ekstraselular. Sumedang: Alqaprint Jatinangor; 2018.

[35] Sriwidodo MIP, Riswanto N, Rostinawati T, Subroto T. Extracellular secretion recombinant of human epidermal growth factor (hEGF) using pectate lyase B (PelB) signal peptide in *Escherichia coli* BL21(DE3).

2019;**10**(4):3319-3324

2016;**21**(3):477-484

2005;**41**:409-416

2009;**494**:3506-3511

1337-1344

2006;**61**(3):876-885

[29] Peng S, Chu Z, Lu J, Li D,

**54**

p. 207

**57**

**Chapter 4**

**Abstract**

Diagnosis

Aptamers for Infectious Disease

Aptamers are in vitro-selected, nucleic acids with unique abilities to bind strongly and specifically to their selective targets (ligands) based on their threedimensional structures. Target binding is generally associated with a change in aptamer structure, which provides a means of linking many output signals to the binding event. Being synthetic, aptamers are less expensive compared to antibodies. Aptamers are also more easily modified chemically or their sequence changed to optimize properties such target specificity, storability and stability. In this chapter we will discuss the potential benefits of applying aptamers to diagnostics with a focus on infectious disease and the unique challenges posed by aptamers for their

*Soma Banerjee and Marit Nilsen-Hamilton*

successful incorporation into reliable aptasensors.

electrochemical impedance spectroscopy

their physical and chemical environment.

**1. Introduction**

**Keywords:** aptamers, SELEX, aptasensors, portable diagnostic tools,

Aptamers, first disclosed in 1990 by three groups [1–3], are ssDNA or RNA molecules capable of binding strongly and specifically to their target (ligand) molecules. Their target binding specificities and affinities are based on their sequence-specific 3D structures. Such properties of aptamers make them analogues of antibodies with unique advantages. For example, aptamers are relatively small (diam. ~2 nm) compared to antibodies (diam. ~15 nm), which allows them to bind targets that are inaccessible to the larger antibodies. Like antibodies, their properties are defined by the ionic conditions and pH in which they are placed. However, being shorter polymers, aptamers are generally more sensitive than antibodies to

In contrast to the time-consuming and expensive production and screening procedures for antibodies, aptamers can be produced faster and more cost effectively by a procedure known as Systemic Evolution of Ligands by Exponential Enrichment (SELEX). Once an aptamer sequence has been identified, its further production is by chemical synthesis, for which variation is negligible compared with the batch to batch variation of antibodies generated in animals or by cell culture. Their synthetic production makes aptamers accessible for selective chemical modifications to enhance their binding specificity or to increase their resistance to degradation. With such advantages over antibodies, aptamers have emerged as new generation molecular recognition elements [4]. In the current chapter, we focus on their impact in diagnosis of infectious disease agents. The reader is referred to other reviews of the application of aptamers to therapy, biosensing and molecular probing [5–10].

#### **Chapter 4**
