How to load and render a sprite in script?

Hi folks,

I've just come over from XNA and wish to port one of my 2D projects onto Unity. I found this article from a former XNA-er which suggested creating a script which instantiates the XNA game class and acts as a proxy between it and Unity. While I appreciate the limitations of this technique, it interests me enough to give it a shot.

XNA provides a SpriteBatch class for sprite rendering, but the article above suggests using a custom mesh in Unity. I've tried and failed to get this to work. I've included my code below, which throws a NullReferenceException in the material constructor. I'm very lost, and would appreciate any insights you can offer.

Apologies for the newbie question!

Cheers!

 using UnityEngine;
 
 public class GameManager : MonoBehaviour
 {
     Mesh mesh;
     Shader shader;
     Material material;
 
     // Start
     void Start()
     {
         mesh = new Mesh();
         shader = new Shader();
         material = new Material(shader);
         material.mainTexture = Resources.Load("Content/Texture") as Texture;    
     }
     
     // Update
     void Update()
     {
         Vector3[] vertices = new Vector3[4];
         vertices[0] = new Vector3(540, 260, 0);
         vertices[1] = new Vector3(740, 260, 0);
         vertices[2] = new Vector3(540, 460, 0);
         vertices[3] = new Vector3(740, 460, 0);
 
         Vector2[] uvs = new Vector2[4];
         uvs[0] = new Vector2(0, 0);
         uvs[1] = new Vector2(0, 0);
         uvs[2] = new Vector2(0, 0);
         uvs[3] = new Vector2(0, 0);
 
         int[] triangles = new int[6];
         triangles[0] = 0;
         triangles[1] = 1;
         triangles[2] = 2;
         triangles[3] = 2;
         triangles[4] = 1;
         triangles[5] = 3;
         
         mesh.vertices = vertices;
         mesh.triangles = triangles;
         mesh.uv = uvs;
         
         Graphics.DrawMesh(mesh, Matrix4x4.identity, material, 0);
     }
 }